This paper will report on the development of a prototype of actively controlled facade module,which is capable of adapting its solar transmittance to changeable solar gains.Hence this new facade offers additional feat...This paper will report on the development of a prototype of actively controlled facade module,which is capable of adapting its solar transmittance to changeable solar gains.Hence this new facade offers additional features with respect to the most popular currently used glass facades,which have fixed solar transmittance indeed.The novel technology is made possible by the creation of an additional 1.5-mm-thick sliding shielding liquid,which flows internally,in order to dynamically adapt the window’s solar transmittance.As compared with competitive technologies,this shielding system has low manufacturing costs,is durable,is completely reversible and always transparent,irrespective of its transmittance state.Specifically,the manufacture of a full-size window prototype and the engineering of the window was carried out;moreover,glass pane bending when subject to hydrostatic pressure was eventually assessed.All this information has been used to set up the industrial process needed for its manufacturing.展开更多
"信息共享与防止冲突"(Shared Awareness and De-confliction)这一军事协调会议为国际社会开展多边合作打击索马里海盗提供了平台。通过分析会议期间所采集的语言素材,并结合护航协调人员英语培训班的教学实践,提出护航英语..."信息共享与防止冲突"(Shared Awareness and De-confliction)这一军事协调会议为国际社会开展多边合作打击索马里海盗提供了平台。通过分析会议期间所采集的语言素材,并结合护航协调人员英语培训班的教学实践,提出护航英语教学的新思路。展开更多
Chlorophyll fluorescence emission, pigment composition and photosynthetic rate of shade-grown cotton ( Gossypium hirsutum L.) plants were measured immediately after suddenly exposing to full sunlight and at regular in...Chlorophyll fluorescence emission, pigment composition and photosynthetic rate of shade-grown cotton ( Gossypium hirsutum L.) plants were measured immediately after suddenly exposing to full sunlight and at regular intervals there after within 15 d. Photoinhibition occurred in shade-grown cotton leaves immediately after exposed to full sunlight. The chlorophyll fluorescence parameter F-v/F-m and PhiPS II, which reflect the efficiency of PS II,obviously decreased in shade-grown leaves, much lower than that of the full sunlight-grown leaves. On the contrary, F-o value was sharply increased. Neither of these parameters could completely recover till next morning. The photoinhibition was chronic and continued for about 4 d, while the F-v/F-m and the net photosynthetic rate ( P-n) continued to decline, then began to increase gradually 6 d later and turned stable after 10 - 12 d, appearing as an acclimation phenomenon. However, the final value of F-v/F-m and P-n did not reach the level as in those leaves grown in the full sunlight ever before. The final P-n was higher by 60% than that before exposure, but lower for more than 40% than that of the full sunlight-grown leaves. The most notable response of chloroplast pigment composition was a pronounced increase in the pool size of carotenoids in xanthophyll cycle over a period of 3 d. The results indicated that when shade-grown cotton seedlings were suddenly transferred to the full sunlight, the decline of F-v/F-m and P-n might associate with the damage of the PS II reaction center. During the light acclimation, photoprotective mechanisms such as the xanthophyll cycle-dependent energy dissipation were increased, so that photodamage in leaves transferred from low to high light might be reduced.展开更多
Lodging is the most important constraint for soybean growth at seedling stage in maize-soybean relay strip intercropping system.In the field experiments,three soybean cultivars Nandou 032-4(shade susceptible cultivar;...Lodging is the most important constraint for soybean growth at seedling stage in maize-soybean relay strip intercropping system.In the field experiments,three soybean cultivars Nandou 032-4(shade susceptible cultivar; B1),Jiuyuehuang(moderately shade tolerant cultivar; B2),and Nandou 12(shade tolerant cultivar; B3) were used to evaluate the relationship between stem stress and lignin metabolism in the stem of soybean.Results showed that the intercropped soybean was in variable light condition throughout the day time and co-growth stage with maize.The xylem area and cross section ratio played a main role to form the stem stress.The B3 both in intercropping and monocropping expressed a high stem stress with higher xylem area,lignin content,and activity of enzymes(phenylalanine ammonia-lyase(PAL),4-coumarate: CoA ligase(4CL),cinnamyl alcohol dehydrogenase(CAD),and peroxidase(POD)) than those of B1 and B2.Among the soybean cultivars and planting pattern,lignin content was positively correlated with stem stress.However,a negative correlation was found between lignin content and actual rate of lodging.In conclusion,the shade tolerant soybean cultivar had larger xylem area,higher lignin content and activities of CAD,4CL,PAL,and POD than other soybean cultivars in intercropping.The lodging in maize-soybean intercropping can be minimized by planting shade tolerant and lodging resistant cultivar of soybean.The lignin content in stem could be a useful indicator for the evaluation of lodging resistance of soybean in intercropping and activities of enzymes were the key factors that influence the lignin biosynthesis.展开更多
Soybean is one of the major oil seed crops,which is usually intercropped with other crops to increase soybean production area and yield.However,soybean is highly sensitive to shading.It is unclear if soybean morpholog...Soybean is one of the major oil seed crops,which is usually intercropped with other crops to increase soybean production area and yield.However,soybean is highly sensitive to shading.It is unclear if soybean morphology responds to shading（i.e.,shade tolerance or avoidance）and which features may be suitable as screening materials in relay strip intercropping.Therefore,in this study,various agronomic characteristics of different soybean genotypes were analyzed under relay intercropping conditions.The soybean materials used in this study exhibited genetic diversity,and the coefficient of variations of the agronomic parameters ranged from 13.84 to 72.08%during the shade period and from 6.44 to 52.49%during the maturity period.The ratios of shading to full irradiance in stem mass fraction（SMF）were almost greater than 1,whereas opposite results were found in the leaves.Compared with full irradiance,the average stem length（SL）,leaf area ratio（LAR）and specific leaf area（SLA）for the two years（2013 and 2014）increased by 0.78,0.47 and 0.65 under shady conditions,respectively.However,the stem diameter（SD）,total biomass（TB）,leaf area（LA）,number of nodes（NN）on the main stem,and number of branches（BN）all decreased.During the shady period,the SL and SMF exhibited a significant negative correlation with yield,and the SD exhibited a significant positive correlation with yield.The correlation between the soybean yield and agronomic parameters during the mature period,except for SL,the first pod height（FPH）,100-seed weight（100-SW）,and reproductive growth period（RGP）,were significant（P〈0.01）,especially for seed weight per branch（SWB）,pods per plant（PP）,BN,and vegetative growth period（VGP）.These results provide an insight into screening the shade tolerance of soybean varieties and can be useful in targeted breeding programs of relay intercropped soybeans.展开更多
In order to prevent or counteract shading,plants enact a complex set of growth and developmental adaptations when they sense a change in light quality caused by other plants in their vicinity.This shade avoidance resp...In order to prevent or counteract shading,plants enact a complex set of growth and developmental adaptations when they sense a change in light quality caused by other plants in their vicinity.This shade avoidance response（SAR）typically includes increased stem elongation at the expense of plant fitness and yield,making it an undesirable trait in an agricultural context.Manipulating the molecular factors involved in SAR can potentially improve productivity by increasing tolerance to higher planting density.However,most of the investigations of the molecular mechanism of SAR have been carried out in Arabidopsis thaliana,and it is presently unclear in how far results of these investigations apply to crop plants.In this review,current data on SAR in crop plants,especially from members of the Solanaceae and Poaceae families,are integrated with data from Arabidopsis,in order to identify the most promising targets for biotechnological approaches.Phytochromes,which detect the change in light caused by neighboring plants,and early signaling components can be targeted to increase plant productivity.However,they control various photomorphogenic processes not necessarily related to shade avoidance.Transcription factors involved in SAR signaling could be better targets to specifically enhance or suppress SAR.Knowledge integration from Arabidopsis and crop plants also indicates factors that could facilitate the control of specific aspects of SAR.Candidates are provided for the regulation of plant architecture,flowering induction and carbohydrate allocation.Yet to-be-elucidated factors that control SAR-dependent changes in biotic resistance and cell wall composition are pointed out.This review also includes an analysis of publicly available gene expression data for maize to augment the sparse molecular data available for this important species.展开更多
To clarify how shade stress affects lignin biosynthesis in soybean stem, two varieties, Nandou 12（shade tolerant） and Nan 032-4（shade susceptible） grew under normal light and shade conditions（the photosynthetical...To clarify how shade stress affects lignin biosynthesis in soybean stem, two varieties, Nandou 12（shade tolerant） and Nan 032-4（shade susceptible） grew under normal light and shade conditions（the photosynthetically active radiation and the ratio of red：far-red were lower than normal light condition）. Lignin accumulation, transcripts of genes involved in lignin biosynthesis, and intermediates content of lignin biosynthesis were analyzed. Both soybean varieties suffered shade stress had increased plant heights and internode lengths, and reduced stem diameters and lignin accumulation in stems. The expression levels of lignin-related genes were significantly influenced by shade stress, with interactions between the light environment and variety. The gene of 3-hydroxylase（C3H）, cinnamoyl-Co A reductase（CCR）, caffeoylCoAO-methyltransferase（CCoAOMT）, and peroxidase（POD） attributed to lignin biosynthesis under shade stress, and the down-regulation of these genes resulted in lower caffeic, sinapic, and ferulic acid levels, which caused a further decrease in lignin biosynthesis. Under shade stress, the shade tolerant soybean variety（Nandou 12） showed stiffer stems, higher lignin content, and greater gene expression level and higher metabolite contents than shade susceptible one. So these characteristics could be used for screening the shade-tolerant soybean for intercropping.展开更多
Increasing the planting density of maize is an effective measure to improve its yield.However,plants under high planting density tend to trigger shade avoidance syndrome(SAS),reducing lodging resistance and ultimately...Increasing the planting density of maize is an effective measure to improve its yield.However,plants under high planting density tend to trigger shade avoidance syndrome(SAS),reducing lodging resistance and ultimately yield drop.Phytochrome B(phyB)plays a dominant role in mediating shade avoidance response.This study constructed two hyperactive mutated alleles of maize PHYB1:ZmPHYB1^(Y98F)(mimicking Y104F of AtPHYB)and ZmPHYB1^(Y359F)(mimicking Y361F of AtPHYB).Ectopic expression of ZmPHYB1^(Y98F) and ZmPHYB1^(Y359F) under the control of the ZmPHYB1 promoter in the Arabidopsis phyB-9 background rendered enhanced activity on complementing the phyB-9 related phenotypes compared with ZmPHYB1^(WT).Moreover,similar to the behavior of ZmPHYB1^(WT),ZmPHYB1Y98F and ZmPHYB1^(Y359F) proteins are localized to the nucleus after red light exposure,and could interact with PIF proteins of maize.In addition,expression of ZmPHYB1^(Y98F) and ZmPHYB1^(Y359F) variants under the control of the native ZmPHYB1 promoter attenuated SAS of maize seedlings subjected to simulated shade treatment.It effectively reduced mature maize’s plant height and ear height in field conditions.The results combined demonstrate the utility of ZmPHYB1^(Y98F) and ZmPHYB1^(Y359F) for attenuating SAS and breeding high density-tolerant varieties of maize.展开更多
Intensively farmed crops used to experience numerous environmental stresses.Among these,shade and drought significantly influence the morpho-physiological and biochemical attributes of plants.However,the interactive e...Intensively farmed crops used to experience numerous environmental stresses.Among these,shade and drought significantly influence the morpho-physiological and biochemical attributes of plants.However,the interactive effect of shade and drought on the growth and development of soybean under dense cropping systems has not been reported yet.This study investigated the interactive effect of PEG-induced osmotic stress and shade on soybean seedlings.The soybean cultivar viz.,C-103 was subjected to PEG-induced osmotic stress from polyethylene glycol 6000(PEG-6000)under shading and non-shading conditions.PEG-induced osmotic stress significantly reduced the relative water contents,morphological parameters,carbohydrates and chlorophyll contents under both light environments.A significant increase was observed in osmoprotectants,reactive oxygen species and antioxidant enzymes in soybean seedlings.Henceforth,the findings revealed that,seedlings grown under non-shading conditions produced more malondialdehyde and hydrogen peroxide contents as compared to the shade-treated plants when subjected to PEG-induced osmotic stress.Likewise,the shaded plants accumulated more sugars and proline than non-shaded ones under drought stress.Moreover,it was found that nonshaded grown plants were more sensitive to PEG-induced osmotic stress than those exposed to shading conditions,which suggested that shade could boost the protective mechanisms against osmotic stress or at least would not exaggerate the adverse effects of PEG-induced osmotic stress in soybean seedlings.展开更多
Shades caused by neighboring tall plants in intercropping systems and weak sunlight are constraints in yield optimization. Shade influences many aspects of plant growth and development, leading to weak stems and susce...Shades caused by neighboring tall plants in intercropping systems and weak sunlight are constraints in yield optimization. Shade influences many aspects of plant growth and development, leading to weak stems and susceptibility to lodging. The plant cell wall is composed of certain proteins that allow the walls to stretch out, a process called cell wall loosening. Shade affects anatomical, morphological, and physiological traits of plants, thus reducing the physical strength of the stem in crops by changing the loosening of cell walls. Flexibility of cells facilitates further modifications such as wall loosening. In addition, shade stress causes increased internode length, and reduced xylem synthesis and photosynthesis. In shaded plants, lignin deposition in vascular bundles and sclerenchyma cells of stems is decreased. Lignin is a light sensitive phenolic compound and shading decreases the transcript abundance of several phenolic compound(flavone and lignin) related genes. Shading significantly influences the metabolic activities of phenylalanine ammonia-lyase(PAL), peroxidase(POD), 4-coumarate: CoA ligase(4 CL), and cinnamyl alcohol dehydrogenase(CAD) involved in lignin biosynthesis. Furthermore, suppression of lignin biosynthesis activities by abiotic stresses causes abnormal phenotypes such as collapsed xylem, bent stems, and growth retardation. In this review, the underlying mechanisms illustrate that under shading conditions reduced lignin content results in slender, weak, and unstable stems. The objective of this review is to elaborate lignin biosynthesis and its variability under stressful environmental conditions, especially in shade stress environments. The effects of shade on stem lignin metabolism are discussed on the morphogenetic, physiological, and proteomic levels.展开更多
Specific aspects of plant cultivation require tests under fully controlled environmentalconditions with restricted energy supply, such as orbit-based space laboratories and low-light conditions.For these growing condi...Specific aspects of plant cultivation require tests under fully controlled environmentalconditions with restricted energy supply, such as orbit-based space laboratories and low-light conditions.For these growing conditions, super dwarf plants have been developed as model crops, and a gibberellindeficientSuper Dwarf Rice genotype was proposed as a model crop for space flight plant experiments.We tested this genotype in a climate chamber experiment under different illumination and nitrogen supplylevels to assess its suitability under scenarios with limited resource availability. A 25% reduction inillumination led to a 75% reduction in yield, mainly due to a 60% reduction in formed tillers and 20%reduction in grain weight, and a 80% reduction in illumination caused total yield loss. Leaf area underreduced illumination was significantly lower, and only marginal changes in the dimensions of leaves wereobserved. Plant photosynthesis was not significantly different between control and 75% illumination. Thiswas explained by a higher photochemical efficiency under lower light conditions and a reduced mesophyllresistance. Therefore, we concluded that this genotype is well-suited for plant experiments under spaceand light-limited conditions since it kept its small stature and showed no shade avoidance mechanisms,such as leaf elongation, which would complicate experiments under low-light conditions. Nitrogenconcentrations of 2.8 and 1.4 mmol/L led to no differences in plant growth. We concluded that a nitrogenconcentration of 1.4 mmol/L is sufficient for this genotype under the light intensities.展开更多
Maize growth and development are regulated by light quality,intensity and photoperiod.Cryptochromes are blue/ultraviolet-A light receptors involved in stem elongation,shade avoidance,and photoperiodic flowering.To inv...Maize growth and development are regulated by light quality,intensity and photoperiod.Cryptochromes are blue/ultraviolet-A light receptors involved in stem elongation,shade avoidance,and photoperiodic flowering.To investigate the function of cryptochrome 1(CRY1) in maize,where it is encoded by Zm CRY1,we obtained two Zm CRY1a genes(Zm CRY1a1 and Zm CRY1a2),both of which share the highest similarity with other gramineous plants,in particular rice CRY1a by phylogenetic analysis.In Arabidopsis,overexpression of Zm CRY1a genes promoted seedling de-etiolation under blue and white light,resulting in dwarfing of mature plants.In seedlings of the maize inbred line Zong 31(Zm CRY1aOE),overexpression of Zm CRY1a genes caused a reduction in the mesocotyl and first leaf sheath lengths due to down-regulation of genes influencing cell elongation.In mature transgenic maize plants,plant height,ear height,and internode length decreased in response to overexpression of Zm CRY1a genes.Expression of Zm CRY1a were insensitive to low blue light(LBL)-induced shade avoidance syndrome(SAS) in Arabidopsis and maize.This prompted us to investigate the regulatory role of the gibberellin and auxin metabolic pathways in the response of Zm CRY1a genes to LBL treatment.We confirmed a link between Zm CRY1a expression and hormonal influence on the growth and development of maize under LBL-induced SAS.These results reveal that Zm CRY1a has a relatively conservative function in regulating maize photomorphogenesis and may guide new strategies for breeding high density-tolerant maize cultivars.展开更多
文摘This paper will report on the development of a prototype of actively controlled facade module,which is capable of adapting its solar transmittance to changeable solar gains.Hence this new facade offers additional features with respect to the most popular currently used glass facades,which have fixed solar transmittance indeed.The novel technology is made possible by the creation of an additional 1.5-mm-thick sliding shielding liquid,which flows internally,in order to dynamically adapt the window’s solar transmittance.As compared with competitive technologies,this shielding system has low manufacturing costs,is durable,is completely reversible and always transparent,irrespective of its transmittance state.Specifically,the manufacture of a full-size window prototype and the engineering of the window was carried out;moreover,glass pane bending when subject to hydrostatic pressure was eventually assessed.All this information has been used to set up the industrial process needed for its manufacturing.
文摘Chlorophyll fluorescence emission, pigment composition and photosynthetic rate of shade-grown cotton ( Gossypium hirsutum L.) plants were measured immediately after suddenly exposing to full sunlight and at regular intervals there after within 15 d. Photoinhibition occurred in shade-grown cotton leaves immediately after exposed to full sunlight. The chlorophyll fluorescence parameter F-v/F-m and PhiPS II, which reflect the efficiency of PS II,obviously decreased in shade-grown leaves, much lower than that of the full sunlight-grown leaves. On the contrary, F-o value was sharply increased. Neither of these parameters could completely recover till next morning. The photoinhibition was chronic and continued for about 4 d, while the F-v/F-m and the net photosynthetic rate ( P-n) continued to decline, then began to increase gradually 6 d later and turned stable after 10 - 12 d, appearing as an acclimation phenomenon. However, the final value of F-v/F-m and P-n did not reach the level as in those leaves grown in the full sunlight ever before. The final P-n was higher by 60% than that before exposure, but lower for more than 40% than that of the full sunlight-grown leaves. The most notable response of chloroplast pigment composition was a pronounced increase in the pool size of carotenoids in xanthophyll cycle over a period of 3 d. The results indicated that when shade-grown cotton seedlings were suddenly transferred to the full sunlight, the decline of F-v/F-m and P-n might associate with the damage of the PS II reaction center. During the light acclimation, photoprotective mechanisms such as the xanthophyll cycle-dependent energy dissipation were increased, so that photodamage in leaves transferred from low to high light might be reduced.
基金the support of the National Key R&D Program of China (2018YFD1000905,2016YFD0300209)the National Natural Science Foundation of China (31671626)
文摘Lodging is the most important constraint for soybean growth at seedling stage in maize-soybean relay strip intercropping system.In the field experiments,three soybean cultivars Nandou 032-4(shade susceptible cultivar; B1),Jiuyuehuang(moderately shade tolerant cultivar; B2),and Nandou 12(shade tolerant cultivar; B3) were used to evaluate the relationship between stem stress and lignin metabolism in the stem of soybean.Results showed that the intercropped soybean was in variable light condition throughout the day time and co-growth stage with maize.The xylem area and cross section ratio played a main role to form the stem stress.The B3 both in intercropping and monocropping expressed a high stem stress with higher xylem area,lignin content,and activity of enzymes(phenylalanine ammonia-lyase(PAL),4-coumarate: CoA ligase(4CL),cinnamyl alcohol dehydrogenase(CAD),and peroxidase(POD)) than those of B1 and B2.Among the soybean cultivars and planting pattern,lignin content was positively correlated with stem stress.However,a negative correlation was found between lignin content and actual rate of lodging.In conclusion,the shade tolerant soybean cultivar had larger xylem area,higher lignin content and activities of CAD,4CL,PAL,and POD than other soybean cultivars in intercropping.The lodging in maize-soybean intercropping can be minimized by planting shade tolerant and lodging resistant cultivar of soybean.The lignin content in stem could be a useful indicator for the evaluation of lodging resistance of soybean in intercropping and activities of enzymes were the key factors that influence the lignin biosynthesis.
基金supported by the National Natural Science Foundation of China (31571615)the National Key Research and Development Program of China (2016YFD0300602, 2016YFD0300209)+1 种基金the Major Project of Education Department in Sichuan, China (16ZA0041)the earmarked fund for China Agriculture Research System, China (CARS-04-PS19)
文摘Soybean is one of the major oil seed crops,which is usually intercropped with other crops to increase soybean production area and yield.However,soybean is highly sensitive to shading.It is unclear if soybean morphology responds to shading（i.e.,shade tolerance or avoidance）and which features may be suitable as screening materials in relay strip intercropping.Therefore,in this study,various agronomic characteristics of different soybean genotypes were analyzed under relay intercropping conditions.The soybean materials used in this study exhibited genetic diversity,and the coefficient of variations of the agronomic parameters ranged from 13.84 to 72.08%during the shade period and from 6.44 to 52.49%during the maturity period.The ratios of shading to full irradiance in stem mass fraction（SMF）were almost greater than 1,whereas opposite results were found in the leaves.Compared with full irradiance,the average stem length（SL）,leaf area ratio（LAR）and specific leaf area（SLA）for the two years（2013 and 2014）increased by 0.78,0.47 and 0.65 under shady conditions,respectively.However,the stem diameter（SD）,total biomass（TB）,leaf area（LA）,number of nodes（NN）on the main stem,and number of branches（BN）all decreased.During the shady period,the SL and SMF exhibited a significant negative correlation with yield,and the SD exhibited a significant positive correlation with yield.The correlation between the soybean yield and agronomic parameters during the mature period,except for SL,the first pod height（FPH）,100-seed weight（100-SW）,and reproductive growth period（RGP）,were significant（P〈0.01）,especially for seed weight per branch（SWB）,pods per plant（PP）,BN,and vegetative growth period（VGP）.These results provide an insight into screening the shade tolerance of soybean varieties and can be useful in targeted breeding programs of relay intercropped soybeans.
基金supported by the funding provided to Dr. Johannes Liesche by Northwest A&F University, China
文摘In order to prevent or counteract shading,plants enact a complex set of growth and developmental adaptations when they sense a change in light quality caused by other plants in their vicinity.This shade avoidance response（SAR）typically includes increased stem elongation at the expense of plant fitness and yield,making it an undesirable trait in an agricultural context.Manipulating the molecular factors involved in SAR can potentially improve productivity by increasing tolerance to higher planting density.However,most of the investigations of the molecular mechanism of SAR have been carried out in Arabidopsis thaliana,and it is presently unclear in how far results of these investigations apply to crop plants.In this review,current data on SAR in crop plants,especially from members of the Solanaceae and Poaceae families,are integrated with data from Arabidopsis,in order to identify the most promising targets for biotechnological approaches.Phytochromes,which detect the change in light caused by neighboring plants,and early signaling components can be targeted to increase plant productivity.However,they control various photomorphogenic processes not necessarily related to shade avoidance.Transcription factors involved in SAR signaling could be better targets to specifically enhance or suppress SAR.Knowledge integration from Arabidopsis and crop plants also indicates factors that could facilitate the control of specific aspects of SAR.Candidates are provided for the regulation of plant architecture,flowering induction and carbohydrate allocation.Yet to-be-elucidated factors that control SAR-dependent changes in biotic resistance and cell wall composition are pointed out.This review also includes an analysis of publicly available gene expression data for maize to augment the sparse molecular data available for this important species.
基金supported by the National Natural Science Foundation of China (31671626)
文摘To clarify how shade stress affects lignin biosynthesis in soybean stem, two varieties, Nandou 12（shade tolerant） and Nan 032-4（shade susceptible） grew under normal light and shade conditions（the photosynthetically active radiation and the ratio of red：far-red were lower than normal light condition）. Lignin accumulation, transcripts of genes involved in lignin biosynthesis, and intermediates content of lignin biosynthesis were analyzed. Both soybean varieties suffered shade stress had increased plant heights and internode lengths, and reduced stem diameters and lignin accumulation in stems. The expression levels of lignin-related genes were significantly influenced by shade stress, with interactions between the light environment and variety. The gene of 3-hydroxylase（C3H）, cinnamoyl-Co A reductase（CCR）, caffeoylCoAO-methyltransferase（CCoAOMT）, and peroxidase（POD） attributed to lignin biosynthesis under shade stress, and the down-regulation of these genes resulted in lower caffeic, sinapic, and ferulic acid levels, which caused a further decrease in lignin biosynthesis. Under shade stress, the shade tolerant soybean variety（Nandou 12） showed stiffer stems, higher lignin content, and greater gene expression level and higher metabolite contents than shade susceptible one. So these characteristics could be used for screening the shade-tolerant soybean for intercropping.
基金financially supported by the Major Program of Guangdong Basic and Applied Research,China(2019B030302006)the National Natural Science Foundation of China(31801377)the funding from the State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources,China(SKLCUSA-b201801)。
文摘Increasing the planting density of maize is an effective measure to improve its yield.However,plants under high planting density tend to trigger shade avoidance syndrome(SAS),reducing lodging resistance and ultimately yield drop.Phytochrome B(phyB)plays a dominant role in mediating shade avoidance response.This study constructed two hyperactive mutated alleles of maize PHYB1:ZmPHYB1^(Y98F)(mimicking Y104F of AtPHYB)and ZmPHYB1^(Y359F)(mimicking Y361F of AtPHYB).Ectopic expression of ZmPHYB1^(Y98F) and ZmPHYB1^(Y359F) under the control of the ZmPHYB1 promoter in the Arabidopsis phyB-9 background rendered enhanced activity on complementing the phyB-9 related phenotypes compared with ZmPHYB1^(WT).Moreover,similar to the behavior of ZmPHYB1^(WT),ZmPHYB1Y98F and ZmPHYB1^(Y359F) proteins are localized to the nucleus after red light exposure,and could interact with PIF proteins of maize.In addition,expression of ZmPHYB1^(Y98F) and ZmPHYB1^(Y359F) variants under the control of the native ZmPHYB1 promoter attenuated SAS of maize seedlings subjected to simulated shade treatment.It effectively reduced mature maize’s plant height and ear height in field conditions.The results combined demonstrate the utility of ZmPHYB1^(Y98F) and ZmPHYB1^(Y359F) for attenuating SAS and breeding high density-tolerant varieties of maize.
基金supported by the National Natural Science Foundation of China(31871552 and 31671445)the Sichuan Science and Technology Program,China(2018HH0108)the Sichuan Innovation Team Project of National Modern Agricultural Industry Technology System,China(sccxtd-2020-20)。
文摘Intensively farmed crops used to experience numerous environmental stresses.Among these,shade and drought significantly influence the morpho-physiological and biochemical attributes of plants.However,the interactive effect of shade and drought on the growth and development of soybean under dense cropping systems has not been reported yet.This study investigated the interactive effect of PEG-induced osmotic stress and shade on soybean seedlings.The soybean cultivar viz.,C-103 was subjected to PEG-induced osmotic stress from polyethylene glycol 6000(PEG-6000)under shading and non-shading conditions.PEG-induced osmotic stress significantly reduced the relative water contents,morphological parameters,carbohydrates and chlorophyll contents under both light environments.A significant increase was observed in osmoprotectants,reactive oxygen species and antioxidant enzymes in soybean seedlings.Henceforth,the findings revealed that,seedlings grown under non-shading conditions produced more malondialdehyde and hydrogen peroxide contents as compared to the shade-treated plants when subjected to PEG-induced osmotic stress.Likewise,the shaded plants accumulated more sugars and proline than non-shaded ones under drought stress.Moreover,it was found that nonshaded grown plants were more sensitive to PEG-induced osmotic stress than those exposed to shading conditions,which suggested that shade could boost the protective mechanisms against osmotic stress or at least would not exaggerate the adverse effects of PEG-induced osmotic stress in soybean seedlings.
基金supported by the National Natural Science Foundation of China (31671626)
文摘Shades caused by neighboring tall plants in intercropping systems and weak sunlight are constraints in yield optimization. Shade influences many aspects of plant growth and development, leading to weak stems and susceptibility to lodging. The plant cell wall is composed of certain proteins that allow the walls to stretch out, a process called cell wall loosening. Shade affects anatomical, morphological, and physiological traits of plants, thus reducing the physical strength of the stem in crops by changing the loosening of cell walls. Flexibility of cells facilitates further modifications such as wall loosening. In addition, shade stress causes increased internode length, and reduced xylem synthesis and photosynthesis. In shaded plants, lignin deposition in vascular bundles and sclerenchyma cells of stems is decreased. Lignin is a light sensitive phenolic compound and shading decreases the transcript abundance of several phenolic compound(flavone and lignin) related genes. Shading significantly influences the metabolic activities of phenylalanine ammonia-lyase(PAL), peroxidase(POD), 4-coumarate: CoA ligase(4 CL), and cinnamyl alcohol dehydrogenase(CAD) involved in lignin biosynthesis. Furthermore, suppression of lignin biosynthesis activities by abiotic stresses causes abnormal phenotypes such as collapsed xylem, bent stems, and growth retardation. In this review, the underlying mechanisms illustrate that under shading conditions reduced lignin content results in slender, weak, and unstable stems. The objective of this review is to elaborate lignin biosynthesis and its variability under stressful environmental conditions, especially in shade stress environments. The effects of shade on stem lignin metabolism are discussed on the morphogenetic, physiological, and proteomic levels.
文摘Specific aspects of plant cultivation require tests under fully controlled environmentalconditions with restricted energy supply, such as orbit-based space laboratories and low-light conditions.For these growing conditions, super dwarf plants have been developed as model crops, and a gibberellindeficientSuper Dwarf Rice genotype was proposed as a model crop for space flight plant experiments.We tested this genotype in a climate chamber experiment under different illumination and nitrogen supplylevels to assess its suitability under scenarios with limited resource availability. A 25% reduction inillumination led to a 75% reduction in yield, mainly due to a 60% reduction in formed tillers and 20%reduction in grain weight, and a 80% reduction in illumination caused total yield loss. Leaf area underreduced illumination was significantly lower, and only marginal changes in the dimensions of leaves wereobserved. Plant photosynthesis was not significantly different between control and 75% illumination. Thiswas explained by a higher photochemical efficiency under lower light conditions and a reduced mesophyllresistance. Therefore, we concluded that this genotype is well-suited for plant experiments under spaceand light-limited conditions since it kept its small stature and showed no shade avoidance mechanisms,such as leaf elongation, which would complicate experiments under low-light conditions. Nitrogenconcentrations of 2.8 and 1.4 mmol/L led to no differences in plant growth. We concluded that a nitrogenconcentration of 1.4 mmol/L is sufficient for this genotype under the light intensities.
基金supported by the National Natural Science Foundation of China (31871709)the Construction of Support System for National Agricultural Green Development Advance Region of Qushui County,Tibet,China (QYXTZX-LS2022-01)+1 种基金the Key Project of Beijing Natural Science Foundation (6151002)the Startup Grants of Henan Agricultural University (30501038,30500823)。
文摘Maize growth and development are regulated by light quality,intensity and photoperiod.Cryptochromes are blue/ultraviolet-A light receptors involved in stem elongation,shade avoidance,and photoperiodic flowering.To investigate the function of cryptochrome 1(CRY1) in maize,where it is encoded by Zm CRY1,we obtained two Zm CRY1a genes(Zm CRY1a1 and Zm CRY1a2),both of which share the highest similarity with other gramineous plants,in particular rice CRY1a by phylogenetic analysis.In Arabidopsis,overexpression of Zm CRY1a genes promoted seedling de-etiolation under blue and white light,resulting in dwarfing of mature plants.In seedlings of the maize inbred line Zong 31(Zm CRY1aOE),overexpression of Zm CRY1a genes caused a reduction in the mesocotyl and first leaf sheath lengths due to down-regulation of genes influencing cell elongation.In mature transgenic maize plants,plant height,ear height,and internode length decreased in response to overexpression of Zm CRY1a genes.Expression of Zm CRY1a were insensitive to low blue light(LBL)-induced shade avoidance syndrome(SAS) in Arabidopsis and maize.This prompted us to investigate the regulatory role of the gibberellin and auxin metabolic pathways in the response of Zm CRY1a genes to LBL treatment.We confirmed a link between Zm CRY1a expression and hormonal influence on the growth and development of maize under LBL-induced SAS.These results reveal that Zm CRY1a has a relatively conservative function in regulating maize photomorphogenesis and may guide new strategies for breeding high density-tolerant maize cultivars.
