Microshoots of Castanea mollissima cv.＇yanshanhong＇ in vitro acquired an enhanced rooting capability with increasing numbers of subculture.In this study,we investigated the effect of successive subculture on adventi...Microshoots of Castanea mollissima cv.＇yanshanhong＇ in vitro acquired an enhanced rooting capability with increasing numbers of subculture.In this study,we investigated the effect of successive subculture on adventitious root formation in vitro by the determination of the endogenous hormone level and the enzyme activity.The levels of indoleacetic acid（IAA）,abscisic acid（ABA）,cytokinins（CTK） and gibberellic acid（GA3） were determined by high performance liquid chromatography（HPLC）,and the activities of indoleacetic acid oxidase（IAAO）,peroxidase oxidase（POD）,and polyphenol oxidase（PPO） were measured by ultraviolet-spectrophotometer assay after the induction of rooting at 2nd,4th,6th and 8th subculture.The relationships between physiological characteristics and subculture numbers or rooting rate were as follows：The levels of endogenous IAA in microshoots gradually increased,and endogenous levels of ABA,CTK and GA3 in microshoots decreased slightly after serial subcultures.The level of IAA was highly correlated with subculture numbers and rooting rates.The ratios of IAA/ABA and IAA/CTK both acutely raised with increasing rooting rate during successive subcultures and had high correlations with rooting rate.The activity of IAAO and POD are significantly negatively related with subculture numbers,and the activity of PPO increased after subcultures.展开更多
Root/shoot(R/S)ratio is an important index for assessing plant health,and has received increased attention in the last decades as a sensitive indicator of plant stress induced by chemical or physical agents.The R/S ra...Root/shoot(R/S)ratio is an important index for assessing plant health,and has received increased attention in the last decades as a sensitive indicator of plant stress induced by chemical or physical agents.The R/S ratio has been discussed in the context of ecological theory and its potential importance in ecological succession,where species follow different strategies for above-ground growth for light or below-ground competition for water and nutrients.We present evidence showing the R/S ratio follows a biphasic dose–response relationship under stress,typical of hormesis.The R/S ratio in response to stress has been widely compared among species and ecological succession classes.It is constrained by a variety of factors such as ontogeny.Furthermore,the current literature lacks dose-response studies incorporating the full dose–response continuum,hence limiting scientific understanding and possible valuable application.The data presented provide an important perspective for new-generation studies that can advance current ecological understanding and improve carbon storage estimates by R/S ratio considerations.Hormetic response of the R/S ratio can have an important role in forestry for producing seedlings with desired characteristics to achieve maximum health/productivity and resilience under plantation conditions.展开更多
Tree peony is well known and sought after for its large, colorful flowers. Its propagation is via vegetative methods. Mech- nisms of the adventitious rooting and the regulation of rooting processes are the principles ...Tree peony is well known and sought after for its large, colorful flowers. Its propagation is via vegetative methods. Mech- nisms of the adventitious rooting and the regulation of rooting processes are the principles and techniques of plant propagation and improvement. Microstructures and fluctuations of phytohormones in the adventitious rooting were studied with the etiolated soft- wood shoots of Paeonia suffkuticosa ＇Yinfen Jinlin＇. There are no pre-primordia in the shoots of the cultivar. Adventitious roots are produced in five stages： shoot selection, primordium initiation, primordium growth, conducting tissue differentiation and root protru- sion. Primordia initiated in the cortex. The contents of the endogenous hormones, IAA, ABA and GA, were 5.842, 0.873 and 1.043 nmol·g^-1 FW on the bases of shoots, respectively. CTKs which included isopentenyl adenine （iPA）, zeatin riboside （ZR） and dihy- drozeatin riboside （DHZR） were 0.949, 0.695 and 2.034 nmol·g^-1 FW, respectively. DHZR is active among CTKs. The ratio of IAA to GA, CTK and ABA clearly increased at the stage of primordium initiation, while they showed low levels at the stages of primor- dium growth. The ratios were restored at the shoot levels at the stage of root protrusion. IBA provoked primordia initiation in the cortex, the vascular cambium, the pith and even in the callus induced on the base of shoots. ]AA levels in the treated shoots increased gradually to its highest level （three times of control） at the stage of conducting tissue differentiation. The ratios of IAA to GA, CTK and ABA clearly decreased at the stage of primordium initiation. The ratio of IAA to ABA is regulated at 10：1.展开更多
A study was conducted at Akron, CO, USA, on a Weld silt loam in 2004 to quantify the effects of water deficit stress on corn (Zea mays, L.) root and shoot biomass. Corn plants were grown under a range of soil bulk den...A study was conducted at Akron, CO, USA, on a Weld silt loam in 2004 to quantify the effects of water deficit stress on corn (Zea mays, L.) root and shoot biomass. Corn plants were grown under a range of soil bulk density and water conditions caused by previous tillage, crop rotation, and irrigation management. Water deficit stress (Dstress) was quantified by the number of days when the water content in the surface 0.3 m deviated from the water content range determined by the Least Limiting Water Range (LLWR). Root and shoot samples were collected at the V6, V12, and R1 growth stages. There was no significant correlation between Dstress and shoot or root biomass at the V6 growth stage. At the V12 and R1 growth stages, there were negative, linear correlations among Dstress and both root biomass and shoot biomass. The proportional decrease of shoot biomass was greater than the proportional decrease in root biomass, leading to an increase in the root:shoot ratio as water deficit stress increased at all growth stages. Determining restrictive soil conditions using the LLWR may be useful for evaluating improvement or degradation of the soil physical environment caused by soil management.展开更多
Phosphorous （P） deficiency is a major restraint factor for crop production and plants have developed several mechanisms to adapt to low P stress. In this study, a set of 271 introgression lines （ILs） were used to ...Phosphorous （P） deficiency is a major restraint factor for crop production and plants have developed several mechanisms to adapt to low P stress. In this study, a set of 271 introgression lines （ILs） were used to characterize the responses of seedlings to low P availability and to identify QTLs for root traits, biomass, and plant height under P-deficiency and P-sufficiency conditions. Plant height, total dry weight, shoot dry weight, and root number were inhibited under P-deficiency, whereas maximum root length （MRL） and root-shoot ratio （RS） were induced by P-deficiency stress. Relative MRL （RMRL, the ratio of MRL under P-deficiency to MRL under P-sufficiency con- dition） and relative RS （RRS） were used to evaluate P-deficiency tolerance at the seedling stage. A total of 24 additive QTLs and 29 pairs of epistatic QTLs were detected, but only qRN4 was detected in both conditions. This suggested that different mechanisms may exist in both P supply levels. QTLs for adaptive traits （RMRL, RRS, RRV, and RRDW） and qRN4 consistently expressed to increase trait stability may contribute to P-deficiency tolerance. Twelve intervals were cluster regions of QTLs for P-deficiency tolerance, and one QTL （qRRSS） showed pleiotropic effects on P-deficiency tolerance and drought tolerance. These interesting QTLs can be used in marker-assisted breeding through the target ILs.展开更多
Tree peony is a famous ornamental plant,while the low propagation rate is the main hurdles hindering the industry development.Till now,the highly efficient regeneration system for tree peony is not established.In this...Tree peony is a famous ornamental plant,while the low propagation rate is the main hurdles hindering the industry development.Till now,the highly efficient regeneration system for tree peony is not established.In this study,using Paeonia ostii’Fengdan’mature embryos,the effects of variations in inoculation method,initiating culture,adventitious shoot induction,rooting media,plant growth regulators(PGRs),and a nonconventional PGR(plant extracts)on regeneration from explants were evaluated.In embryo cultures,embryonic callus induction rate of 1/4 embryos was the highest among those of embryos with other three technical treatments(whole embryos,1/2 embryos,and pieces of embryos).The woody plant medium(WPM)containing 1.0 mg·L^(-1)6-BA,0.5 mg·L^(-1)GA3,30.0 g·L^(-1)sucrose,and 3.0 g·L^(-1)phytagel significantly improved shoot induction and multiplication.3.0 mg·L^(-1)plant extracts promoted hypocotyl germination,rooting,and root growth,in direct embryo culture,and a combination of 3.0 mg·L^(-1)plant extracts+2.0 mg·L^(-1)IBA+1.5 mg·L^(-1)IAA produced optimal rooting induction rate for multiple shoots in direct embryo culture and indirect somatic embryogenesis.For the three in vitro micropropagation methods,the highest shoot proliferation coefficient(5.4±0.2)was obtained with indirect somatic embryogenesis.Fortunately,the propagation ability of shoots remains high,even when culture propagation was continued for more than two years.Thus,a reliable system for plant regeneration from mature embryos derived from P.ostii’Fengdan’callus and two direct embryo culture systems have been established.The novel regeneration system could facilitate uniform seedling production.展开更多
The equilibrium between root, shoot and growth stability under different soil water conditions were investigated in a tube experiment of winter wheat. The water supplying treatments included： sufficient irrigation at...The equilibrium between root, shoot and growth stability under different soil water conditions were investigated in a tube experiment of winter wheat. The water supplying treatments included： sufficient irrigation at whole growth phase, moderate deficiency irrigation at whole growth phase, serious deficiency irrigation at whole growth phase, sufficient irrigation at jointing stage, tillering stage, flowering stage, and fillering respectively, after moderate and serious water deficit during their previous growth stage. Root and shoot biomass were measured. On the basis of the cooperative root-shoot interactions model, the equilibrium and growth stability were studied on the strength of the kinetics system theory. There was only one varying equilibrium point between the root and shoot over the life time of the winter wheat plant. Water stress prolonged the duration of stable growth, the more serious the water deficit, the longer the period of stable growth. The duration of stable growth was shortened and that of unstable growth was prolonged after water recovery. The growth behavior of the plants exposed to moderate water deficit shifted from stable to unstable until the end of the growth, after rewatering at flowering. In the life-time of the crop, the root and shoot had been adjusting themselves in structure and function so as to maintain an equilibrium, but could not achieve the equilibrium state for long. They were always in an unbalanced state from the beginning to the end of growth. This was the essence of root-shoot equilibrium. Water stress inhibited the function of root and shoot, reduced root shoot interactions, and as a result, the plant growth gradually tended to stabilize. Rewatering enhanced root shoot interactions, prolonged duration of instable growth. Rewatering at flowering could upset the inherent relativity during the long time of stable growth from flowering to filling stage, thus leading to unstable growth and enhanced dry matter accumulating rate in the whole plant.展开更多
The effects of neodymium nitrate （Nd^3＋） on the adventitious rooting of Dendrobium densiflorum shoot cuttings were studied. The addition of Nd^3＋ （5 μmol/L） to culture medium significantly increased rooting fre...The effects of neodymium nitrate （Nd^3＋） on the adventitious rooting of Dendrobium densiflorum shoot cuttings were studied. The addition of Nd^3＋ （5 μmol/L） to culture medium significantly increased rooting frequency. Histological investigation showed that Nd^3＋ did not change the process of root initiation. Nd^3＋ did not influence total endogenous cytokinin levels, but significantly increased the level of endogenous indole-3-acetic acid （IAA） in the base of shoot cuttings. Compared to the control, the ratio of IAA/cytokinins was very high in the Nd^3＋ treatment. These results suggested that the enhanced rooting frequency may be related to the increase in endogenous IAA level in Nd^3＋ treatment. Analysis of enzyme activities showed that the enhanced accumulation of the endogenous IAA by Nd^3＋ should not be attributed to inhibition of IAA decomposition by IAA oxidase or promotion of cytokinin decomposition by cytokinin oxidase. Besides, Nd^3＋ increased the ratio of reduced glutathione （GSH） and oxidized glutathione （GSSG） in the process of adventitious rooting while the ratio of ascorbate （ASC） to dehydroascorbate （DHA） was not affected.展开更多
The effect of stock-plant etiolation on adventitious rooting of single-node leafy cuttings (SNCs) made from coppice shoots from different age groups of donor plants were investigated for teak (Tectona grandis Linn. f....The effect of stock-plant etiolation on adventitious rooting of single-node leafy cuttings (SNCs) made from coppice shoots from different age groups of donor plants were investigated for teak (Tectona grandis Linn. f.). When donor plants age were 1-, 2-, 3-, 4-, and 5-year-old, they were coppiced and maintained in the dark for etiolation, while a parallel set was kept in normal light in an open environment. After 20 days, coppice shoots were made into SNCs which were cultured under intermittent mist for rooting. Stock-plant etiolation significantly increased percent rooting, shoot and root length, and number of roots per SNC, but callusing at the base of SNCs decreased. Etiolated SNCs have shown 71.7% rooting, whereas for controls (non-etiolated), the response was 41.7%. The effect of aging on callusing, rooting and sprouting of etiolated and non-etiolated coppice shoots cuttings varied widely. Aging of donor plants decreased rooting and sprouting capability in SNCs and increased callusing at the base of etiolated cuttings. The results showed that stock-plant etiolation in 1-, 2-, 3-, 4-, and 5-year-old donor plants hastened rooting potential by rejuvenation of coppice shoots.展开更多
The dynamic relationship of dry matter accumulation and distribution between winter wheat root and shoot was studied under different soil water conditions. The dry matter accumulation in root was greatly influenced by...The dynamic relationship of dry matter accumulation and distribution between winter wheat root and shoot was studied under different soil water conditions. The dry matter accumulation in root was greatly influenced by water stress, so as to the final root weight of the treatment with 40% field moisture capacity(FMC) was less than 1/4 of that of the treatment with 80% FMC on average. Water stress during the 3-leaf stage to the tillering stage had the greatest influence on root, and the influence of water stress during the jointing stage to the booting stage on shoot was greater than root. However, water stress during the tillering stage to the booting stage had a balanced effect on root and shoot, and the proportion of dry matter that distributed to root and shoot was almost the same after rewatering. Water recovery during the jointing stage to booting stage could promote R/S, but the increasing degree was related to the duration of water limitation. Soil water condition had the lowest effect on R/S during the flowering stage to the filling stage and the maximal effect on R/S during the jointing stage to the heading stage, R/S of 40% FMC treatment was 20.93 and 126.09% higher than that of 60% FMC and 80% FMC treatments respectively at this period.展开更多
A highly reproducible and efficient in vitro shoot regeneration system was developed in a potential medicinal plant, Albizia lebbeck using root explants. Root explants from 15 day-old-aseptic seedlings were cultured o...A highly reproducible and efficient in vitro shoot regeneration system was developed in a potential medicinal plant, Albizia lebbeck using root explants. Root explants from 15 day-old-aseptic seedlings were cultured on Murashige and Skoog （MS） medium supplemented with different concentrations （0.5, 2.5, 5.0, 7.5 and 10.0 μM） of 6-Benzyladenine （BA）, Kinetin （Kn）, 2-Isopentenyl adenine （2-iP） singly as well as in combination with α-Naphthalene acetic acid （NAA） （0.1, 0.5, 1.0, 1.5 and 2.0 μM）. The highest rate of shoot multiplication （16.0 ± 1.87 for the average shoot number and 5.16 ± 0.38 cm for shoot length） was achieved on MS medium supplemented with 7.5 μM BA and 0.5 μM NAA. The effects of medium type, medium strength, pH and subculture on shoot induction and proliferation were also tested. An average of 21.6±2.87 shoots per explants could be obtained following this protocol. Rooting was achieved on microshoots using half strength MS medium with 2.0 μM Indole-3-butyric acid （IBA） after four weeks of culture. The in vitro raised healthy plantlets were successfully established in earthen pots containing garden soil and grown in greenhouse with 〉80% survival rate.展开更多
This study aimed to investigate the differences in shoot and root traits, and water use and water use efficiency（WUE） in drought tolerant（DT） maize（Zea mays L.） hybrids under full and deficit irrigated condition...This study aimed to investigate the differences in shoot and root traits, and water use and water use efficiency（WUE） in drought tolerant（DT） maize（Zea mays L.） hybrids under full and deficit irrigated conditions. A two-year greenhouse study was conducted with four hybrids（one conventional hybrid, 33D53AM, two commercial DT hybrids, P1151 AM, N75H, and an experimental hybrid, Exp HB） grown under two water regimes（I（100） and I（50）, referring to 100 and 50% of evapotranspiration requirements）. Under water stress, the hybids P1151 AM, N75, and Exp HB showed more drought tolerance and had either greater shoot dry weight or less dry weight reduction than the conventional hybrid（33 D53 AM）. However, these three hybrids responded to water stress using different mechanisms. Compared with the conventional hybrid, the two commercial DT hybrids（P1151 AM and N75H） had a smaller leaf area, shoot dry weight, and root system per plant. As a result, these hybrids used less water but had a higher WUE compared with the conventional hybrid. In contrast, the experimental hybrid（ExpHB） produced more shoot biomass by silking stage at both irrigation levels than all other hybrids, but it had relatively lower WUE. The hybrids demonstrated different drought response mechanisms that may require different irrigation management strategies. More investigation and validation are needed under field conditions and in different soil types.展开更多
Nitrate is a major nitrogen resource for plant growth and development and acts as both a crucial nutrient and a signaling molecule for plants;hence,understanding nitrate signaling is important for crop production.Absc...Nitrate is a major nitrogen resource for plant growth and development and acts as both a crucial nutrient and a signaling molecule for plants;hence,understanding nitrate signaling is important for crop production.Abscisic acid(ABA)has been demonstrated to be involved in nitrate signaling,but the underlying mechanism is largely unknown in apple.In this study,we found that exogenous ABA inhibited the transport of nitrate from roots to shoots in apple,and the transcription of the nitrate transporter MdNRT1.5/MdNPF7.3 was noticeably reduced at the transcriptional level by ABA,which inhibited the transport of nitrate from roots to shoots.Then,it was found that the ABA-responsive transcription factor MdABI5 bound directly to the ABRE recognition site of the MdNRT1.5 promoter and suppressed its expression.Overexpression of MdABI5 inhibited ABA-mediated transport of nitrate from roots to shoots.Overall,these results demonstrate that MdABI5 regulates the transport of nitrate from roots to shoots partially by mediating the expression of MdNRT1.5,illuminating the molecular mechanism by which ABA regulates nitrate transport in apple.展开更多
In this paper, root-shoot relationships of seedlings of Manchurican ash (Fraxinus mandchurica) in pots is studied in green house. The results show that roots and shoots have the co-ordination of growth and roots and s...In this paper, root-shoot relationships of seedlings of Manchurican ash (Fraxinus mandchurica) in pots is studied in green house. The results show that roots and shoots have the co-ordination of growth and roots and shoots of ash have the same growth dynamics. There are very close relationships between toall root mass and total shoot mass, between fine root mass and leaf mass in this experiments. At the end growing season, ash root-shoot mass ratio and fine root-leaf mass ratio are 1 .85 and 2.01 respectively. These ratios are difference during growth season. There are larger roots than shoots on seedling stage. Low nitrogen and phosphorus produce higher root-shoot ratio, and high nutrient concentrations decrease the ratios.展开更多
The variation in shoot and root seedling growth traits was compared among three Faidherbia albida （Del）. A. Chev. provenances originating from Kenya （Taveta）, Malawi （Bolero） and Ghana （Bolgatanga）; representi...The variation in shoot and root seedling growth traits was compared among three Faidherbia albida （Del）. A. Chev. provenances originating from Kenya （Taveta）, Malawi （Bolero） and Ghana （Bolgatanga）; representing east, south and west Africa, respectively. Bulked seeds from three provenances were grown in two soil types （clay and sand） at the World Agroforestry Centre nursery, Nairobi. Seedlings grown in clay soil had high shoot growth and shoot to root ratios but shorter root length, lower number of nodules and specific root length compared to seedlings in sand soil. Shoot to root ratios reduced with time and this was more pronounced in sand soil. Overall, the Bolero and Taveta provenances had higher growth than the Bolgatanga provenance. This was probably because plants grown in nutrient-rich clay soil invest more in shoot growth as compared to root growth. Longer root growth in sand soil shows a better adaptive mechanism that increases competitive ability and survival in nutrient-poor systems. Variations observed among the seedling variables such us shoot and root growth could be used for early selection for reforestation and agroforestry in predominantly clay and sand soil areas.展开更多
Phytohormones play important roles in plant growth and development,and polyploids are thought to be an important method for plant breeding.However,the relationship between ploidy and phytohormone is still unclear.In t...Phytohormones play important roles in plant growth and development,and polyploids are thought to be an important method for plant breeding.However,the relationship between ploidy and phytohormone is still unclear.In this study,barley at three ploidy levels were produced by microspore culture.Therefore,we further analyzed the phytohormone content in the shoots and roots of the three kinds of barley materials to study the effect of ploidy on phytohormones accumulation and distribution.The results showed that Abscisic acid(ABA),gibberellin(GA),jasmonic acid(JA),auxin(IAA),salicylic acid(SA)and cytokinin(CTK)were successfully determined in shoots and roots using LC-MS(liquid chromatography mass spectrometry).By comparing the shoots of the haploid and diploid plants,it was found that the distribution trend of the six phytohormones was consistent,and another consistent trend was found in the roots of the diploid and tetraploid plants.In addition,we further analyzed the shoot/root ratio of the different phytohormones to identify the potential differences for haploid,diploid and tetraploid.Here,the relationship between ploidy and phytohormone we provided would provide new insights into understanding the new phenotypes that occur in polyploid species.展开更多
In vitro cultures of loquat cultivar Mardan were established using shoot apices after treating with NaOCl (5%,7%,10%,12%,14% (v/v)) for 12 min and HgCl2 (0.01%,0.05%,0.10%,0.20%,0.25% (w/v)) for 2 min.A maximum surviv...In vitro cultures of loquat cultivar Mardan were established using shoot apices after treating with NaOCl (5%,7%,10%,12%,14% (v/v)) for 12 min and HgCl2 (0.01%,0.05%,0.10%,0.20%,0.25% (w/v)) for 2 min.A maximum survival rate of 70% was recorded after surface sterilization with 10% NaOCl.Caulogenic response was assessed on Murashige and Skoog (MS) medium fortified with assorted combinations of the cytokinins,benzylaminopurine (BAP),kinetin,and N6-(2-isopentyl)adenine (2iP).Treatment of BAP 1.5 mg/L combined with 2iP 9.0 mg/L and kinetin 1.5 mg/L was found to be optimum for shoot morphogenesis in terms of the number and subsequent growth of shoots,while the highest shoot length was yielded by the combination of BAP 0.5 mg/L,kinetin 0.5 mg/L,and 2iP 3 mg/L.Higher levels of cytokinins induced callogenesis,vitrification and stunted growth to some extent.For rhizogenesis,uniform sized micro-shoots were excised and transferred to half-strength MS medium containing auxins.The best rooting expression was observed with naphthaleneacetic acid (NAA) 1 mg/L combined with indole-3-butyric acid (IBA) 2 mg/L and paclobutrazol (PBZ) 1 mg/L.展开更多
The experiment with the green shoot cutting propagation of Larix olgensis was made in the Maoer Mountain Forestry Farm on July 5, 1990. After the callus formed of the cutting base before adventitious roots came out th...The experiment with the green shoot cutting propagation of Larix olgensis was made in the Maoer Mountain Forestry Farm on July 5, 1990. After the callus formed of the cutting base before adventitious roots came out the materials were collected from the cutting base and fixed in FAA solution. By the paraffin sections and anatomical observatio-n. the results indicted that it needed 40 days from the cutting to the rooting. The induced primordium of the cutting was endogenous in origin, which came from : (1) vascular cambium of the callus, and became roots; (2) meristematic cell population in the intersect between the cambium and xylem ray of the cutting base. There were extruding, crushing process and enzymolysis when the adventitious roots broke through the outer layers in two rooting types.展开更多
The effect of auxins （IAA or IBA at 100, 200, 500 mg.L J） on rooting and sprouting parameters differed significantly （p 〈 0.05）. Rooting and sprouting percentages were higher in some treatments while other parame...The effect of auxins （IAA or IBA at 100, 200, 500 mg.L J） on rooting and sprouting parameters differed significantly （p 〈 0.05）. Rooting and sprouting percentages were higher in some treatments while other parameters were significantly higher in other treatments. The results of the present study revealed that rooting was significantly （p 〈 0.05） affected by the length of cuttings, as well as the position of shoots and type of cuttings. On average, 86.0 per cent rooting was observed in the 30-cm long cuttings com- pared to the other two lengths of cuttings, i.e., 20 and 25 cm, irrespective of any auxin treatment. In a control set, without any auxin treatment, a maximum of 60.0% rooting was recorded in the 30-cm long cuttings and a minimum of 40.0% of the cuttings rooted in the 20-cm long cuttings. Similarly, cuttings collected from the lower and upper portions of shoots resulted in 72.5 and 52.5 per cent rooting respectively, irrespective of auxin treatments. Maximum rooting was observed in the lower portion （40.0%） of cutting com- pared to the upper portion （30.0%） in the control set without auxin treatment. Leafless branches produced maximum （72.0%） rooting compared to the leafy cuttings （35.0%）, irrespective of the auxin treatment. The leafy cuttings produces a minimum of 15.0% sprout- ing and rooting in the control set.展开更多
基金supported by Special Scientific Research Fund for Doctor Subjects of Universities(NO20060022010)China National key Tech R&D Program (No2006BAD18B0202)
文摘Microshoots of Castanea mollissima cv.＇yanshanhong＇ in vitro acquired an enhanced rooting capability with increasing numbers of subculture.In this study,we investigated the effect of successive subculture on adventitious root formation in vitro by the determination of the endogenous hormone level and the enzyme activity.The levels of indoleacetic acid（IAA）,abscisic acid（ABA）,cytokinins（CTK） and gibberellic acid（GA3） were determined by high performance liquid chromatography（HPLC）,and the activities of indoleacetic acid oxidase（IAAO）,peroxidase oxidase（POD）,and polyphenol oxidase（PPO） were measured by ultraviolet-spectrophotometer assay after the induction of rooting at 2nd,4th,6th and 8th subculture.The relationships between physiological characteristics and subculture numbers or rooting rate were as follows：The levels of endogenous IAA in microshoots gradually increased,and endogenous levels of ABA,CTK and GA3 in microshoots decreased slightly after serial subcultures.The level of IAA was highly correlated with subculture numbers and rooting rates.The ratios of IAA/ABA and IAA/CTK both acutely raised with increasing rooting rate during successive subcultures and had high correlations with rooting rate.The activity of IAAO and POD are significantly negatively related with subculture numbers,and the activity of PPO increased after subcultures.
基金supported by JSPS KAKENHI Grant Number JP17F17102German Research Foundation(BE4189/1-3)+1 种基金the US Air Force [AFOSR FA9550-13-1-0047]Exxon Mobil Foundation [S18200000000256]
文摘Root/shoot(R/S)ratio is an important index for assessing plant health,and has received increased attention in the last decades as a sensitive indicator of plant stress induced by chemical or physical agents.The R/S ratio has been discussed in the context of ecological theory and its potential importance in ecological succession,where species follow different strategies for above-ground growth for light or below-ground competition for water and nutrients.We present evidence showing the R/S ratio follows a biphasic dose–response relationship under stress,typical of hormesis.The R/S ratio in response to stress has been widely compared among species and ecological succession classes.It is constrained by a variety of factors such as ontogeny.Furthermore,the current literature lacks dose-response studies incorporating the full dose–response continuum,hence limiting scientific understanding and possible valuable application.The data presented provide an important perspective for new-generation studies that can advance current ecological understanding and improve carbon storage estimates by R/S ratio considerations.Hormetic response of the R/S ratio can have an important role in forestry for producing seedlings with desired characteristics to achieve maximum health/productivity and resilience under plantation conditions.
文摘Tree peony is well known and sought after for its large, colorful flowers. Its propagation is via vegetative methods. Mech- nisms of the adventitious rooting and the regulation of rooting processes are the principles and techniques of plant propagation and improvement. Microstructures and fluctuations of phytohormones in the adventitious rooting were studied with the etiolated soft- wood shoots of Paeonia suffkuticosa ＇Yinfen Jinlin＇. There are no pre-primordia in the shoots of the cultivar. Adventitious roots are produced in five stages： shoot selection, primordium initiation, primordium growth, conducting tissue differentiation and root protru- sion. Primordia initiated in the cortex. The contents of the endogenous hormones, IAA, ABA and GA, were 5.842, 0.873 and 1.043 nmol·g^-1 FW on the bases of shoots, respectively. CTKs which included isopentenyl adenine （iPA）, zeatin riboside （ZR） and dihy- drozeatin riboside （DHZR） were 0.949, 0.695 and 2.034 nmol·g^-1 FW, respectively. DHZR is active among CTKs. The ratio of IAA to GA, CTK and ABA clearly increased at the stage of primordium initiation, while they showed low levels at the stages of primor- dium growth. The ratios were restored at the shoot levels at the stage of root protrusion. IBA provoked primordia initiation in the cortex, the vascular cambium, the pith and even in the callus induced on the base of shoots. ]AA levels in the treated shoots increased gradually to its highest level （three times of control） at the stage of conducting tissue differentiation. The ratios of IAA to GA, CTK and ABA clearly decreased at the stage of primordium initiation. The ratio of IAA to ABA is regulated at 10：1.
文摘A study was conducted at Akron, CO, USA, on a Weld silt loam in 2004 to quantify the effects of water deficit stress on corn (Zea mays, L.) root and shoot biomass. Corn plants were grown under a range of soil bulk density and water conditions caused by previous tillage, crop rotation, and irrigation management. Water deficit stress (Dstress) was quantified by the number of days when the water content in the surface 0.3 m deviated from the water content range determined by the Least Limiting Water Range (LLWR). Root and shoot samples were collected at the V6, V12, and R1 growth stages. There was no significant correlation between Dstress and shoot or root biomass at the V6 growth stage. At the V12 and R1 growth stages, there were negative, linear correlations among Dstress and both root biomass and shoot biomass. The proportional decrease of shoot biomass was greater than the proportional decrease in root biomass, leading to an increase in the root:shoot ratio as water deficit stress increased at all growth stages. Determining restrictive soil conditions using the LLWR may be useful for evaluating improvement or degradation of the soil physical environment caused by soil management.
基金supported by the Hi-Tech Research and Development Program of China (No. 2006AA10Z158 and No. 2006AA100101)the "948" Project (No. 2006-G1)+1 种基金China National Key Technologies R & D Program (No. 2006BAD13B01-6)the Program for Chang Jiang Scholars and Innovative Research Team in University, Program of Introducing Talents of Discipline to Universi-ties in China (111-2-03).
文摘Phosphorous （P） deficiency is a major restraint factor for crop production and plants have developed several mechanisms to adapt to low P stress. In this study, a set of 271 introgression lines （ILs） were used to characterize the responses of seedlings to low P availability and to identify QTLs for root traits, biomass, and plant height under P-deficiency and P-sufficiency conditions. Plant height, total dry weight, shoot dry weight, and root number were inhibited under P-deficiency, whereas maximum root length （MRL） and root-shoot ratio （RS） were induced by P-deficiency stress. Relative MRL （RMRL, the ratio of MRL under P-deficiency to MRL under P-sufficiency con- dition） and relative RS （RRS） were used to evaluate P-deficiency tolerance at the seedling stage. A total of 24 additive QTLs and 29 pairs of epistatic QTLs were detected, but only qRN4 was detected in both conditions. This suggested that different mechanisms may exist in both P supply levels. QTLs for adaptive traits （RMRL, RRS, RRV, and RRDW） and qRN4 consistently expressed to increase trait stability may contribute to P-deficiency tolerance. Twelve intervals were cluster regions of QTLs for P-deficiency tolerance, and one QTL （qRRSS） showed pleiotropic effects on P-deficiency tolerance and drought tolerance. These interesting QTLs can be used in marker-assisted breeding through the target ILs.
基金supported by National Key R&D Program of China (Grant No.2019YFD1001500)China Agriculture Research System (Grant No.CARS-21)+1 种基金the National Natural Science Foundation of China (Grant Nos.31972440,31972455)the Agricultural Science and Technology Innovation Program (ASTIP)of the Chinese Academy of Agricultural Sciences (Grant No.CAASASTIPIVFCAAS)。
文摘Tree peony is a famous ornamental plant,while the low propagation rate is the main hurdles hindering the industry development.Till now,the highly efficient regeneration system for tree peony is not established.In this study,using Paeonia ostii’Fengdan’mature embryos,the effects of variations in inoculation method,initiating culture,adventitious shoot induction,rooting media,plant growth regulators(PGRs),and a nonconventional PGR(plant extracts)on regeneration from explants were evaluated.In embryo cultures,embryonic callus induction rate of 1/4 embryos was the highest among those of embryos with other three technical treatments(whole embryos,1/2 embryos,and pieces of embryos).The woody plant medium(WPM)containing 1.0 mg·L^(-1)6-BA,0.5 mg·L^(-1)GA3,30.0 g·L^(-1)sucrose,and 3.0 g·L^(-1)phytagel significantly improved shoot induction and multiplication.3.0 mg·L^(-1)plant extracts promoted hypocotyl germination,rooting,and root growth,in direct embryo culture,and a combination of 3.0 mg·L^(-1)plant extracts+2.0 mg·L^(-1)IBA+1.5 mg·L^(-1)IAA produced optimal rooting induction rate for multiple shoots in direct embryo culture and indirect somatic embryogenesis.For the three in vitro micropropagation methods,the highest shoot proliferation coefficient(5.4±0.2)was obtained with indirect somatic embryogenesis.Fortunately,the propagation ability of shoots remains high,even when culture propagation was continued for more than two years.Thus,a reliable system for plant regeneration from mature embryos derived from P.ostii’Fengdan’callus and two direct embryo culture systems have been established.The novel regeneration system could facilitate uniform seedling production.
基金supported by the National Basic Research Program of China(973 Program,G1999011709)the Natural Science Foundation of Guangdong Province,China(33135).
文摘The equilibrium between root, shoot and growth stability under different soil water conditions were investigated in a tube experiment of winter wheat. The water supplying treatments included： sufficient irrigation at whole growth phase, moderate deficiency irrigation at whole growth phase, serious deficiency irrigation at whole growth phase, sufficient irrigation at jointing stage, tillering stage, flowering stage, and fillering respectively, after moderate and serious water deficit during their previous growth stage. Root and shoot biomass were measured. On the basis of the cooperative root-shoot interactions model, the equilibrium and growth stability were studied on the strength of the kinetics system theory. There was only one varying equilibrium point between the root and shoot over the life time of the winter wheat plant. Water stress prolonged the duration of stable growth, the more serious the water deficit, the longer the period of stable growth. The duration of stable growth was shortened and that of unstable growth was prolonged after water recovery. The growth behavior of the plants exposed to moderate water deficit shifted from stable to unstable until the end of the growth, after rewatering at flowering. In the life-time of the crop, the root and shoot had been adjusting themselves in structure and function so as to maintain an equilibrium, but could not achieve the equilibrium state for long. They were always in an unbalanced state from the beginning to the end of growth. This was the essence of root-shoot equilibrium. Water stress inhibited the function of root and shoot, reduced root shoot interactions, and as a result, the plant growth gradually tended to stabilize. Rewatering enhanced root shoot interactions, prolonged duration of instable growth. Rewatering at flowering could upset the inherent relativity during the long time of stable growth from flowering to filling stage, thus leading to unstable growth and enhanced dry matter accumulating rate in the whole plant.
基金supported by the Specialized Research Fund for the Doctoral Program of Higher Education of China (20060359006)
文摘The effects of neodymium nitrate （Nd^3＋） on the adventitious rooting of Dendrobium densiflorum shoot cuttings were studied. The addition of Nd^3＋ （5 μmol/L） to culture medium significantly increased rooting frequency. Histological investigation showed that Nd^3＋ did not change the process of root initiation. Nd^3＋ did not influence total endogenous cytokinin levels, but significantly increased the level of endogenous indole-3-acetic acid （IAA） in the base of shoot cuttings. Compared to the control, the ratio of IAA/cytokinins was very high in the Nd^3＋ treatment. These results suggested that the enhanced rooting frequency may be related to the increase in endogenous IAA level in Nd^3＋ treatment. Analysis of enzyme activities showed that the enhanced accumulation of the endogenous IAA by Nd^3＋ should not be attributed to inhibition of IAA decomposition by IAA oxidase or promotion of cytokinin decomposition by cytokinin oxidase. Besides, Nd^3＋ increased the ratio of reduced glutathione （GSH） and oxidized glutathione （GSSG） in the process of adventitious rooting while the ratio of ascorbate （ASC） to dehydroascorbate （DHA） was not affected.
文摘The effect of stock-plant etiolation on adventitious rooting of single-node leafy cuttings (SNCs) made from coppice shoots from different age groups of donor plants were investigated for teak (Tectona grandis Linn. f.). When donor plants age were 1-, 2-, 3-, 4-, and 5-year-old, they were coppiced and maintained in the dark for etiolation, while a parallel set was kept in normal light in an open environment. After 20 days, coppice shoots were made into SNCs which were cultured under intermittent mist for rooting. Stock-plant etiolation significantly increased percent rooting, shoot and root length, and number of roots per SNC, but callusing at the base of SNCs decreased. Etiolated SNCs have shown 71.7% rooting, whereas for controls (non-etiolated), the response was 41.7%. The effect of aging on callusing, rooting and sprouting of etiolated and non-etiolated coppice shoots cuttings varied widely. Aging of donor plants decreased rooting and sprouting capability in SNCs and increased callusing at the base of etiolated cuttings. The results showed that stock-plant etiolation in 1-, 2-, 3-, 4-, and 5-year-old donor plants hastened rooting potential by rejuvenation of coppice shoots.
基金supported by the National Natural Science Foundation of China(49971042).
文摘The dynamic relationship of dry matter accumulation and distribution between winter wheat root and shoot was studied under different soil water conditions. The dry matter accumulation in root was greatly influenced by water stress, so as to the final root weight of the treatment with 40% field moisture capacity(FMC) was less than 1/4 of that of the treatment with 80% FMC on average. Water stress during the 3-leaf stage to the tillering stage had the greatest influence on root, and the influence of water stress during the jointing stage to the booting stage on shoot was greater than root. However, water stress during the tillering stage to the booting stage had a balanced effect on root and shoot, and the proportion of dry matter that distributed to root and shoot was almost the same after rewatering. Water recovery during the jointing stage to booting stage could promote R/S, but the increasing degree was related to the duration of water limitation. Soil water condition had the lowest effect on R/S during the flowering stage to the filling stage and the maximal effect on R/S during the jointing stage to the heading stage, R/S of 40% FMC treatment was 20.93 and 126.09% higher than that of 60% FMC and 80% FMC treatments respectively at this period.
基金supported from the DST-FIST (2005-2010)UGC- SAP (DRS-I) Programmes (2009-2014), Govt of India, New Delhi
文摘A highly reproducible and efficient in vitro shoot regeneration system was developed in a potential medicinal plant, Albizia lebbeck using root explants. Root explants from 15 day-old-aseptic seedlings were cultured on Murashige and Skoog （MS） medium supplemented with different concentrations （0.5, 2.5, 5.0, 7.5 and 10.0 μM） of 6-Benzyladenine （BA）, Kinetin （Kn）, 2-Isopentenyl adenine （2-iP） singly as well as in combination with α-Naphthalene acetic acid （NAA） （0.1, 0.5, 1.0, 1.5 and 2.0 μM）. The highest rate of shoot multiplication （16.0 ± 1.87 for the average shoot number and 5.16 ± 0.38 cm for shoot length） was achieved on MS medium supplemented with 7.5 μM BA and 0.5 μM NAA. The effects of medium type, medium strength, pH and subculture on shoot induction and proliferation were also tested. An average of 21.6±2.87 shoots per explants could be obtained following this protocol. Rooting was achieved on microshoots using half strength MS medium with 2.0 μM Indole-3-butyric acid （IBA） after four weeks of culture. The in vitro raised healthy plantlets were successfully established in earthen pots containing garden soil and grown in greenhouse with 〉80% survival rate.
基金supported in part by the UDSA-Ogallala Aquifer ProgramTexas A&M Agri Life Research Cropping System Program, USAthe USDA National Institute of Food and Agriculture Hatch Project, USA (TEX09438)
文摘This study aimed to investigate the differences in shoot and root traits, and water use and water use efficiency（WUE） in drought tolerant（DT） maize（Zea mays L.） hybrids under full and deficit irrigated conditions. A two-year greenhouse study was conducted with four hybrids（one conventional hybrid, 33D53AM, two commercial DT hybrids, P1151 AM, N75H, and an experimental hybrid, Exp HB） grown under two water regimes（I（100） and I（50）, referring to 100 and 50% of evapotranspiration requirements）. Under water stress, the hybids P1151 AM, N75, and Exp HB showed more drought tolerance and had either greater shoot dry weight or less dry weight reduction than the conventional hybrid（33 D53 AM）. However, these three hybrids responded to water stress using different mechanisms. Compared with the conventional hybrid, the two commercial DT hybrids（P1151 AM and N75H） had a smaller leaf area, shoot dry weight, and root system per plant. As a result, these hybrids used less water but had a higher WUE compared with the conventional hybrid. In contrast, the experimental hybrid（ExpHB） produced more shoot biomass by silking stage at both irrigation levels than all other hybrids, but it had relatively lower WUE. The hybrids demonstrated different drought response mechanisms that may require different irrigation management strategies. More investigation and validation are needed under field conditions and in different soil types.
基金This work was supported by grants from the National Key R&D Program of China(2018YFD1000100)National Natural Science Foundation of China(31772288 and 31972378)+1 种基金China Agriculture Research System of MOF and MARA(CARS-27)the Agricultural Variety Improvement Project of Shandong Province(2019LZGC007).
文摘Nitrate is a major nitrogen resource for plant growth and development and acts as both a crucial nutrient and a signaling molecule for plants;hence,understanding nitrate signaling is important for crop production.Abscisic acid(ABA)has been demonstrated to be involved in nitrate signaling,but the underlying mechanism is largely unknown in apple.In this study,we found that exogenous ABA inhibited the transport of nitrate from roots to shoots in apple,and the transcription of the nitrate transporter MdNRT1.5/MdNPF7.3 was noticeably reduced at the transcriptional level by ABA,which inhibited the transport of nitrate from roots to shoots.Then,it was found that the ABA-responsive transcription factor MdABI5 bound directly to the ABRE recognition site of the MdNRT1.5 promoter and suppressed its expression.Overexpression of MdABI5 inhibited ABA-mediated transport of nitrate from roots to shoots.Overall,these results demonstrate that MdABI5 regulates the transport of nitrate from roots to shoots partially by mediating the expression of MdNRT1.5,illuminating the molecular mechanism by which ABA regulates nitrate transport in apple.
文摘In this paper, root-shoot relationships of seedlings of Manchurican ash (Fraxinus mandchurica) in pots is studied in green house. The results show that roots and shoots have the co-ordination of growth and roots and shoots of ash have the same growth dynamics. There are very close relationships between toall root mass and total shoot mass, between fine root mass and leaf mass in this experiments. At the end growing season, ash root-shoot mass ratio and fine root-leaf mass ratio are 1 .85 and 2.01 respectively. These ratios are difference during growth season. There are larger roots than shoots on seedling stage. Low nitrogen and phosphorus produce higher root-shoot ratio, and high nutrient concentrations decrease the ratios.
基金funded by the World Agroforestry Centre (ICRAF) through the Science Domains 1 (Agroforestry productivity) and 3 (Tree diversity, domestication and delivery)
文摘The variation in shoot and root seedling growth traits was compared among three Faidherbia albida （Del）. A. Chev. provenances originating from Kenya （Taveta）, Malawi （Bolero） and Ghana （Bolgatanga）; representing east, south and west Africa, respectively. Bulked seeds from three provenances were grown in two soil types （clay and sand） at the World Agroforestry Centre nursery, Nairobi. Seedlings grown in clay soil had high shoot growth and shoot to root ratios but shorter root length, lower number of nodules and specific root length compared to seedlings in sand soil. Shoot to root ratios reduced with time and this was more pronounced in sand soil. Overall, the Bolero and Taveta provenances had higher growth than the Bolgatanga provenance. This was probably because plants grown in nutrient-rich clay soil invest more in shoot growth as compared to root growth. Longer root growth in sand soil shows a better adaptive mechanism that increases competitive ability and survival in nutrient-poor systems. Variations observed among the seedling variables such us shoot and root growth could be used for early selection for reforestation and agroforestry in predominantly clay and sand soil areas.
基金Key Technology R&D Project of Shanghai Agriculture-developed with Science&Technology Program,China(Grant No.2018(1-2))the Natural Science Foundation of Shanghai,China(Grant No.19ZR1417000)+2 种基金the National Key Research and Development Program of China(2018YFD1000702-5)the Climbing Plan of Shanghai Academy of Agricultural Sciences(2022)the earmarked fund for China Agriculture Research System of MOF and MARA(CARS-05-01A-02).
文摘Phytohormones play important roles in plant growth and development,and polyploids are thought to be an important method for plant breeding.However,the relationship between ploidy and phytohormone is still unclear.In this study,barley at three ploidy levels were produced by microspore culture.Therefore,we further analyzed the phytohormone content in the shoots and roots of the three kinds of barley materials to study the effect of ploidy on phytohormones accumulation and distribution.The results showed that Abscisic acid(ABA),gibberellin(GA),jasmonic acid(JA),auxin(IAA),salicylic acid(SA)and cytokinin(CTK)were successfully determined in shoots and roots using LC-MS(liquid chromatography mass spectrometry).By comparing the shoots of the haploid and diploid plants,it was found that the distribution trend of the six phytohormones was consistent,and another consistent trend was found in the roots of the diploid and tetraploid plants.In addition,we further analyzed the shoot/root ratio of the different phytohormones to identify the potential differences for haploid,diploid and tetraploid.Here,the relationship between ploidy and phytohormone we provided would provide new insights into understanding the new phenotypes that occur in polyploid species.
基金Project(No.20-1540/R&D/09)supported by the Higher Education Commission(HEC)of Pakistan
文摘In vitro cultures of loquat cultivar Mardan were established using shoot apices after treating with NaOCl (5%,7%,10%,12%,14% (v/v)) for 12 min and HgCl2 (0.01%,0.05%,0.10%,0.20%,0.25% (w/v)) for 2 min.A maximum survival rate of 70% was recorded after surface sterilization with 10% NaOCl.Caulogenic response was assessed on Murashige and Skoog (MS) medium fortified with assorted combinations of the cytokinins,benzylaminopurine (BAP),kinetin,and N6-(2-isopentyl)adenine (2iP).Treatment of BAP 1.5 mg/L combined with 2iP 9.0 mg/L and kinetin 1.5 mg/L was found to be optimum for shoot morphogenesis in terms of the number and subsequent growth of shoots,while the highest shoot length was yielded by the combination of BAP 0.5 mg/L,kinetin 0.5 mg/L,and 2iP 3 mg/L.Higher levels of cytokinins induced callogenesis,vitrification and stunted growth to some extent.For rhizogenesis,uniform sized micro-shoots were excised and transferred to half-strength MS medium containing auxins.The best rooting expression was observed with naphthaleneacetic acid (NAA) 1 mg/L combined with indole-3-butyric acid (IBA) 2 mg/L and paclobutrazol (PBZ) 1 mg/L.
文摘The experiment with the green shoot cutting propagation of Larix olgensis was made in the Maoer Mountain Forestry Farm on July 5, 1990. After the callus formed of the cutting base before adventitious roots came out the materials were collected from the cutting base and fixed in FAA solution. By the paraffin sections and anatomical observatio-n. the results indicted that it needed 40 days from the cutting to the rooting. The induced primordium of the cutting was endogenous in origin, which came from : (1) vascular cambium of the callus, and became roots; (2) meristematic cell population in the intersect between the cambium and xylem ray of the cutting base. There were extruding, crushing process and enzymolysis when the adventitious roots broke through the outer layers in two rooting types.
文摘The effect of auxins （IAA or IBA at 100, 200, 500 mg.L J） on rooting and sprouting parameters differed significantly （p 〈 0.05）. Rooting and sprouting percentages were higher in some treatments while other parameters were significantly higher in other treatments. The results of the present study revealed that rooting was significantly （p 〈 0.05） affected by the length of cuttings, as well as the position of shoots and type of cuttings. On average, 86.0 per cent rooting was observed in the 30-cm long cuttings com- pared to the other two lengths of cuttings, i.e., 20 and 25 cm, irrespective of any auxin treatment. In a control set, without any auxin treatment, a maximum of 60.0% rooting was recorded in the 30-cm long cuttings and a minimum of 40.0% of the cuttings rooted in the 20-cm long cuttings. Similarly, cuttings collected from the lower and upper portions of shoots resulted in 72.5 and 52.5 per cent rooting respectively, irrespective of auxin treatments. Maximum rooting was observed in the lower portion （40.0%） of cutting com- pared to the upper portion （30.0%） in the control set without auxin treatment. Leafless branches produced maximum （72.0%） rooting compared to the leafy cuttings （35.0%）, irrespective of the auxin treatment. The leafy cuttings produces a minimum of 15.0% sprout- ing and rooting in the control set.
