The effects of maternal salinity and light incubation on the salinity tolerance of the facultative halophyte Anabasis setifera during their germination stages were assessed. Seeds were collected from non-saline habita...The effects of maternal salinity and light incubation on the salinity tolerance of the facultative halophyte Anabasis setifera during their germination stages were assessed. Seeds were collected from non-saline habitats in Egypt and saline habitats in the United Arab Emirates （UAE）. The seeds of the two populations were germinated in 0, 100, 200, 400, 600 and 800 mM NaCI, and incubated at 25℃/15℃ in both 12-h light and 12-h darkness regimes and continuous darkness. Significantly more seeds germinated in the Egyptian population than in the UAE population. Salinity tolerance was significantly greater with the Egyptian population than with the UAE population, especially under the conditions of higher salinities. The difference in salinity tolerance between the seeds of two populations was attributed to their seed mass. In addition, germination was significantly faster for the Egyptian population than for the UAE population. Most of the saline treated seeds were able to recover their germination when transferred to distilled water, but this depended on their maternal salinity and light incubation. Recovery from higher salinities was significantly better for the seeds under darkness than for those under light in the UAE population, but the reverse was true for the seeds in the Egyptian population. The higher salinity tolerance for the A. setifera seeds from the non-saline Egyptian population and the lower salinity tolerance for the seeds from the saline UAE population cannot explain their natural distribution. Further studies about other possible roles, such as levels of different promoting and inhibiting phytohormones, are needed to understand the importance of salinity as an environmentally induced maternal effect.展开更多
Plants use a sophisticated immune system to perceive pathogen infection and activate immune responses in a tightly controlled manner.In barley,Hv WRKY2 acts as a repressor in barley disease resistance to the powdery m...Plants use a sophisticated immune system to perceive pathogen infection and activate immune responses in a tightly controlled manner.In barley,Hv WRKY2 acts as a repressor in barley disease resistance to the powdery mildew fungus,Blumeria graminis f.sp.hordei(Bgh).However,the molecular features of Hv WRKY2 in its DNA-binding and repressor functions,as well as its target genes,are uncharacterized.We show that the W-box binding of Hv WRKY2 requires an intact WRKY domain and an upstream sequence of~75 amino acids,and the Hv WRKY2 W-box binding activity is linked to its repressor function in disease resistance.Chromatin immunoprecipitation(ChIP)-seq analysis identified HvCEBiP,a putative chitin receptor gene,as a target gene of Hv WRKY2 in overexpressing transgenic barley plants.ChIP-qPCR and Electrophoretic Mobility Shift Assay(EMSA)verified the direct binding of Hv WRKY2 to a W-boxcontaining sequence in the HvCEBiP promoter.Hv CEBiP positively regulates resistance against Bgh in barley.Our findings suggest that Hv WRKY2 represses barley basal immunity by directly targeting pathogen-associated molecular pattern(PAMP)recognition receptor genes,suggesting that Hv CEBiP and likely chitin signaling function in barley PAMP-triggered immune responses to Bgh infection.展开更多
With the aim to investigate if the halophyte Halothamnus iraqensis Botsch. can be suitable for re-vegetation and remediation of salt-affected lands, this study evaluated(1) the effects of photoperiod, thermoperiod, st...With the aim to investigate if the halophyte Halothamnus iraqensis Botsch. can be suitable for re-vegetation and remediation of salt-affected lands, this study evaluated(1) the effects of photoperiod, thermoperiod, storage period and wings' presence on its seed germination, and(2) the ability of its seeds to have successful germination recovery after salt stress. Germination tests in different photoperiods(12 h light/12 h darkness and total darkness) and thermoperiods(15℃/20℃ and 20℃/25℃) were conducted for seeds collected in 2012, 2013, 2014, 2015 and 2016. The seeds collected in 2016 were sown under different salinity levels(0, 100, 200, 400 and 600 m M Na Cl) to assess the salinity tolerance during the germination. Wings' presence highly inhibited seed germination of this species in both photoperiods and thermoperiods under all salinity level treatments. In addition, the germination recovery occurred well when seeds were deprived of their wings. The photoperiod of 12 h light/12 h darkness and the thermoperiod of 15℃/20℃ were the best conditions for seed germination. Germination percentages of H. iraqensis seeds decreased with the increasing storage duration, especially after three years of the collection. In addition, H. iraqensis seeds were able to germinate under different salinity levels, and their germination percentages decreased with increasing salinity levels. H. iraqensis seeds have the ability to recover their germination after alleviating the salt stress, irrespective of photoperiod, highlighting the halophilous character of this species.展开更多
Germination timing is highly regulated in short-lived plant species since it strongly influences recruitment success of vegetation.In deserts,the spatiotemporal distribution of plant-available water is highly episodic...Germination timing is highly regulated in short-lived plant species since it strongly influences recruitment success of vegetation.In deserts,the spatiotemporal distribution of plant-available water is highly episodic and unpredictable,making winter months more favorable for seed germination when other abiotic conditions co-occur.We hypothesized that changes in photoperiod and thermoperiod would impact germination more in seeds that had undergone in situ storage.We assessed 21 annual and short-lived perennial species in the Arabian Desert to find(1)if seeds were dormant at maturity,(2)if in situ seed storage increased germination percentage compared with no storage,(3)if photoperiod and thermoperiod germination requirements were influenced by in situ storage,and(4)if a phylogenetic association in seed germination could be observed.Seeds of each species collected in early 2017 were divided into two batches.One was tested for germination within one week(fresh seeds).The other was stored in situ at the maternal location(stored seeds)until October 2017 and tested for seed germination in the first week of November.Seed germination was conducted in incubators at two thermoperiods(15℃/20℃ and 20℃/30℃;12 h/12 h),and two photoperiods(12 and 0 h light per day).Results indicated that seed germination percentages of 13 species were significantly enhanced by in situ storage.A thermoperiod response was exhibited by stored,but not fresh seeds.Light exposure increased germination of fresh seeds but had only a minimal effect on stored seeds.Germination traits exhibited no phylogenetic correlation.This result indicated that selection pressure for germination strategy was stronger than that for taxonomic traits of these desert species.展开更多
The population structure of tree species has been explored in order to elucidate regeneration potential of the subalpine forests of Indian western Himalaya. For this study, the subalpine forest area was divided into t...The population structure of tree species has been explored in order to elucidate regeneration potential of the subalpine forests of Indian western Himalaya. For this study, the subalpine forest area was divided into three strata, i.e., lower altitude （〈3000 m）; mid-altitude （3000-3200 m）; and high altitude （〉3200m）. Considering the major compositional attributes, an increase in altitude came with a significant decline in tree density and the total basal area for all the sites. However, no such clear trends were observed for recruits （i.e., seedlings and saplings）. Seedling density did not exhibit uniform patterns for sites and altitude strata. In general, overall seedling density was greater at the Pindari site compared to the Lata and Tungnath sites. By comparison, significant variation in seedling density along the altitude strata was recorded for the Tungnath and Pindari sites only. Likewise, sapling density patterns varied across the sites and altitude strata, and significant variation in sapling density along the altitude strata was recorded only for the Lata site. At the Pin- daft site, the continuous increase in sapling density along with increasing altitude was revealing. The Pindari forests of exhibited expanding population structure. In contrast, greater accumulation of individuals in the sapling class and sharp decline toward both higher tree classes and lower seedling classes was generally apparent for the Lata and Tungnath sites. This indicates that the replacement in tree size classes from sapling stage is not proportional and the population may decline in the long-term. Considerable variation in patterns of forest and dominant species popula- tion structure were evident across altitude strata. But in all cases irrespective of sites, we found growth at the high-altitude stratum, in the form of entire forests or dominant species. This trend deserves further investigation to explore its relevance under changing climate scenarios.展开更多
Understanding variability in seed germination among populations is essential for planning an effective germplasm collection for restoration and conservation purposes.The knowledge of germination and dormancy patterns ...Understanding variability in seed germination among populations is essential for planning an effective germplasm collection for restoration and conservation purposes.The knowledge of germination and dormancy patterns among populations of desert grasses is crucial for determining the potential of the species and populations to be used for restoration and conservation as well as forage production.Variability in seed germination of Panicum turgidum Forssk and Pennisetum divisum(Gmel.)Henr.in the desert of Kuwait was evaluated in different populations in May 2017.Experiment of seed germination(25 seeds and 4 replicates)was conducted for each population at night/day temperatures of 15℃/20℃and 20℃/30℃under the following light condition:continuous darkness or 12 h/12 h light/dark.Results showed that seed masses of both species strongly varied according to their seed provenances,and both species produced heavier seeds in population with a higher soil electrical conductivity.Seed germination percentage considerably varied between two species,and the variation in P.turgidum was greater(17%–49%)than that of P.divisum(72%–93%).Germination percentage in P.turgidum was greater at high temperature(20℃/30℃)than at low temperature(15℃/20℃).However,temperature regimes had no effect on germination percentage of P.divisum seeds.Mean germination time of both species exhibited significant inter-population variability.This result is especially relevant to assure the selection of the best population of each species and the regeneration success of the species.Besides this,inter-population variability also provides valuable information for enhancing our understanding of the mechanisms that regulate seed germination and how they might be related to seed provenance.展开更多
Angelica glauca is one of the important medicinal plants and it is widely used by indigenous communities for different purposes. The present study analyzes variability in reproductive characters of A. glauca. The repr...Angelica glauca is one of the important medicinal plants and it is widely used by indigenous communities for different purposes. The present study analyzes variability in reproductive characters of A. glauca. The reproductive parts were found having significant positive correlation with altitude (e.g.,number of umbellets /umber r= 0.857,p<0.05; umbel diameter r=0.735,p<0.05).展开更多
Mounds constructed by plateau zokors,which is widely distributed in alpine meadows significantly modified plant community structure.However,the variations of plant community structure under the disturbance of plateau ...Mounds constructed by plateau zokors,which is widely distributed in alpine meadows significantly modified plant community structure.However,the variations of plant community structure under the disturbance of plateau zokor-made mound are less concerned.Therefore,we investigated the responses of plant community on zokor-made mound of different years(1 a and 3-4 a),and compared with undisturbed sites(no mound)in an alpine meadow in the eastern Qinghai-Tibetan Plateau(QTP),China.Species richness,coverage and Simpson diversity index were all significantly reduced by the presence of zokor-made mound,but plant heights were significantly increased,particularly in grasses and sedges.Several perennial forage species showed an increased importance value and niche breadth,including Koeleria macrantha,Elymus nutans and Poa pratensis.The effect of zokor-made mound on niche overlap showed that more intense interspecific competition produced a greater utilization of environmental resources.And this interspecific niche overlap was strengthened as succession progressed.The bare mound created by zokor burrowing activities provided a colonizing opportunity for non-dominant forage species,resulting in abundant plant species and plant diversity during the succession period.We concluded that presence of zokor-made mound was conducive to regeneration and vitality of plant community in alpine meadows,thus improving their resilience to anthropogenic stress.展开更多
Aims To determine if the germination response of desert plant species to a period of aerial storage in field conditions(i.e.mature seeds that remain attached to the parent plant)is comparable to seeds harvested at mat...Aims To determine if the germination response of desert plant species to a period of aerial storage in field conditions(i.e.mature seeds that remain attached to the parent plant)is comparable to seeds harvested at maturity and stored in ambient laboratory conditions,to better understand the role of aerial seed bank in the germina-tion ecology of desert plants,using one annual and two perennial species.Methods Seeds of three desert plants(Anastatica hierochuntica,Blepharis ciliaris and Scrophularia deserti)that matured in June 2014,were collected from wild plants in June and November 2014,and ger-minated under two photoperiods(0,12 hours light)and three ther-moperiods(night/day temperatures of 15/25,20/30 and 25/35°c).Important Findings Seeds of B.ciliaris and S.deserti had significantly higher germination percentages when harvested and stored for five months,compared to being stored in the aerial seed bank.Germination percentages of these two species increased with decreasing temperature and in the presence of light.These results indicate that these species use a com-bination of aerial and soil seed banks to maintain a percentage of viable seeds through favourable germination periods.Germination percentages of A.hierochuntica were high under all tested circum-stances,indicating that this species relies mainly on the aerial seed bank to maintain a percentage of viable seeds through favourable germination periods.This study shows that the population survival strategies of an aerial seed bank are species-specific.These results have practical implications for conservation and habitat restoration for these species,and also for their propagation since early collec-tion of mature fruits and ex situ storage will result in greater germi-nation percentages of some species.展开更多
基金supported by the Qatar National Research Fund(5-260-1-053)
文摘The effects of maternal salinity and light incubation on the salinity tolerance of the facultative halophyte Anabasis setifera during their germination stages were assessed. Seeds were collected from non-saline habitats in Egypt and saline habitats in the United Arab Emirates （UAE）. The seeds of the two populations were germinated in 0, 100, 200, 400, 600 and 800 mM NaCI, and incubated at 25℃/15℃ in both 12-h light and 12-h darkness regimes and continuous darkness. Significantly more seeds germinated in the Egyptian population than in the UAE population. Salinity tolerance was significantly greater with the Egyptian population than with the UAE population, especially under the conditions of higher salinities. The difference in salinity tolerance between the seeds of two populations was attributed to their seed mass. In addition, germination was significantly faster for the Egyptian population than for the UAE population. Most of the saline treated seeds were able to recover their germination when transferred to distilled water, but this depended on their maternal salinity and light incubation. Recovery from higher salinities was significantly better for the seeds under darkness than for those under light in the UAE population, but the reverse was true for the seeds in the Egyptian population. The higher salinity tolerance for the A. setifera seeds from the non-saline Egyptian population and the lower salinity tolerance for the seeds from the saline UAE population cannot explain their natural distribution. Further studies about other possible roles, such as levels of different promoting and inhibiting phytohormones, are needed to understand the importance of salinity as an environmentally induced maternal effect.
基金supported by National Key Research and Development Program of China(2018YFD1000703,2018YFD1000700)Strategic Priority Research Program of the Chinese Academy of Sciences(XDB11020400)+3 种基金National Program on Research and Development of Transgenic Plants(2016ZX08009-003-001)Startup Fund for Advanced Talents of Lushan Botanical GardenChinese Academy of Science(2020ZWZX03 and 2020ZWZX05)the“Double Hundred and Double Thousand”Talent Project of Jiujiang City(jjsbsq2020026)。
文摘Plants use a sophisticated immune system to perceive pathogen infection and activate immune responses in a tightly controlled manner.In barley,Hv WRKY2 acts as a repressor in barley disease resistance to the powdery mildew fungus,Blumeria graminis f.sp.hordei(Bgh).However,the molecular features of Hv WRKY2 in its DNA-binding and repressor functions,as well as its target genes,are uncharacterized.We show that the W-box binding of Hv WRKY2 requires an intact WRKY domain and an upstream sequence of~75 amino acids,and the Hv WRKY2 W-box binding activity is linked to its repressor function in disease resistance.Chromatin immunoprecipitation(ChIP)-seq analysis identified HvCEBiP,a putative chitin receptor gene,as a target gene of Hv WRKY2 in overexpressing transgenic barley plants.ChIP-qPCR and Electrophoretic Mobility Shift Assay(EMSA)verified the direct binding of Hv WRKY2 to a W-boxcontaining sequence in the HvCEBiP promoter.Hv CEBiP positively regulates resistance against Bgh in barley.Our findings suggest that Hv WRKY2 represses barley basal immunity by directly targeting pathogen-associated molecular pattern(PAMP)recognition receptor genes,suggesting that Hv CEBiP and likely chitin signaling function in barley PAMP-triggered immune responses to Bgh infection.
基金funded by Kuwait Institute for Scientific Research
文摘With the aim to investigate if the halophyte Halothamnus iraqensis Botsch. can be suitable for re-vegetation and remediation of salt-affected lands, this study evaluated(1) the effects of photoperiod, thermoperiod, storage period and wings' presence on its seed germination, and(2) the ability of its seeds to have successful germination recovery after salt stress. Germination tests in different photoperiods(12 h light/12 h darkness and total darkness) and thermoperiods(15℃/20℃ and 20℃/25℃) were conducted for seeds collected in 2012, 2013, 2014, 2015 and 2016. The seeds collected in 2016 were sown under different salinity levels(0, 100, 200, 400 and 600 m M Na Cl) to assess the salinity tolerance during the germination. Wings' presence highly inhibited seed germination of this species in both photoperiods and thermoperiods under all salinity level treatments. In addition, the germination recovery occurred well when seeds were deprived of their wings. The photoperiod of 12 h light/12 h darkness and the thermoperiod of 15℃/20℃ were the best conditions for seed germination. Germination percentages of H. iraqensis seeds decreased with the increasing storage duration, especially after three years of the collection. In addition, H. iraqensis seeds were able to germinate under different salinity levels, and their germination percentages decreased with increasing salinity levels. H. iraqensis seeds have the ability to recover their germination after alleviating the salt stress, irrespective of photoperiod, highlighting the halophilous character of this species.
基金This work was supported by the Kuwait Institute for Scientific Research (KISR),Kuwait.
文摘Germination timing is highly regulated in short-lived plant species since it strongly influences recruitment success of vegetation.In deserts,the spatiotemporal distribution of plant-available water is highly episodic and unpredictable,making winter months more favorable for seed germination when other abiotic conditions co-occur.We hypothesized that changes in photoperiod and thermoperiod would impact germination more in seeds that had undergone in situ storage.We assessed 21 annual and short-lived perennial species in the Arabian Desert to find(1)if seeds were dormant at maturity,(2)if in situ seed storage increased germination percentage compared with no storage,(3)if photoperiod and thermoperiod germination requirements were influenced by in situ storage,and(4)if a phylogenetic association in seed germination could be observed.Seeds of each species collected in early 2017 were divided into two batches.One was tested for germination within one week(fresh seeds).The other was stored in situ at the maternal location(stored seeds)until October 2017 and tested for seed germination in the first week of November.Seed germination was conducted in incubators at two thermoperiods(15℃/20℃ and 20℃/30℃;12 h/12 h),and two photoperiods(12 and 0 h light per day).Results indicated that seed germination percentages of 13 species were significantly enhanced by in situ storage.A thermoperiod response was exhibited by stored,but not fresh seeds.Light exposure increased germination of fresh seeds but had only a minimal effect on stored seeds.Germination traits exhibited no phylogenetic correlation.This result indicated that selection pressure for germination strategy was stronger than that for taxonomic traits of these desert species.
基金supported by the Ministry of Environment & Forests,Government of India(research grant 10/28/98-CS/BR)
文摘The population structure of tree species has been explored in order to elucidate regeneration potential of the subalpine forests of Indian western Himalaya. For this study, the subalpine forest area was divided into three strata, i.e., lower altitude （〈3000 m）; mid-altitude （3000-3200 m）; and high altitude （〉3200m）. Considering the major compositional attributes, an increase in altitude came with a significant decline in tree density and the total basal area for all the sites. However, no such clear trends were observed for recruits （i.e., seedlings and saplings）. Seedling density did not exhibit uniform patterns for sites and altitude strata. In general, overall seedling density was greater at the Pindari site compared to the Lata and Tungnath sites. By comparison, significant variation in seedling density along the altitude strata was recorded for the Tungnath and Pindari sites only. Likewise, sapling density patterns varied across the sites and altitude strata, and significant variation in sapling density along the altitude strata was recorded only for the Lata site. At the Pin- daft site, the continuous increase in sapling density along with increasing altitude was revealing. The Pindari forests of exhibited expanding population structure. In contrast, greater accumulation of individuals in the sapling class and sharp decline toward both higher tree classes and lower seedling classes was generally apparent for the Lata and Tungnath sites. This indicates that the replacement in tree size classes from sapling stage is not proportional and the population may decline in the long-term. Considerable variation in patterns of forest and dominant species popula- tion structure were evident across altitude strata. But in all cases irrespective of sites, we found growth at the high-altitude stratum, in the form of entire forests or dominant species. This trend deserves further investigation to explore its relevance under changing climate scenarios.
基金supported by the Kuwait Institute for Scientific Research(KISR)
文摘Understanding variability in seed germination among populations is essential for planning an effective germplasm collection for restoration and conservation purposes.The knowledge of germination and dormancy patterns among populations of desert grasses is crucial for determining the potential of the species and populations to be used for restoration and conservation as well as forage production.Variability in seed germination of Panicum turgidum Forssk and Pennisetum divisum(Gmel.)Henr.in the desert of Kuwait was evaluated in different populations in May 2017.Experiment of seed germination(25 seeds and 4 replicates)was conducted for each population at night/day temperatures of 15℃/20℃and 20℃/30℃under the following light condition:continuous darkness or 12 h/12 h light/dark.Results showed that seed masses of both species strongly varied according to their seed provenances,and both species produced heavier seeds in population with a higher soil electrical conductivity.Seed germination percentage considerably varied between two species,and the variation in P.turgidum was greater(17%–49%)than that of P.divisum(72%–93%).Germination percentage in P.turgidum was greater at high temperature(20℃/30℃)than at low temperature(15℃/20℃).However,temperature regimes had no effect on germination percentage of P.divisum seeds.Mean germination time of both species exhibited significant inter-population variability.This result is especially relevant to assure the selection of the best population of each species and the regeneration success of the species.Besides this,inter-population variability also provides valuable information for enhancing our understanding of the mechanisms that regulate seed germination and how they might be related to seed provenance.
文摘Angelica glauca is one of the important medicinal plants and it is widely used by indigenous communities for different purposes. The present study analyzes variability in reproductive characters of A. glauca. The reproductive parts were found having significant positive correlation with altitude (e.g.,number of umbellets /umber r= 0.857,p<0.05; umbel diameter r=0.735,p<0.05).
基金funded by the Lushan Plant Special Project of Lushan Botanical Garden,Chinese Academy of Sciences(2019ZWZX01).
文摘Mounds constructed by plateau zokors,which is widely distributed in alpine meadows significantly modified plant community structure.However,the variations of plant community structure under the disturbance of plateau zokor-made mound are less concerned.Therefore,we investigated the responses of plant community on zokor-made mound of different years(1 a and 3-4 a),and compared with undisturbed sites(no mound)in an alpine meadow in the eastern Qinghai-Tibetan Plateau(QTP),China.Species richness,coverage and Simpson diversity index were all significantly reduced by the presence of zokor-made mound,but plant heights were significantly increased,particularly in grasses and sedges.Several perennial forage species showed an increased importance value and niche breadth,including Koeleria macrantha,Elymus nutans and Poa pratensis.The effect of zokor-made mound on niche overlap showed that more intense interspecific competition produced a greater utilization of environmental resources.And this interspecific niche overlap was strengthened as succession progressed.The bare mound created by zokor burrowing activities provided a colonizing opportunity for non-dominant forage species,resulting in abundant plant species and plant diversity during the succession period.We concluded that presence of zokor-made mound was conducive to regeneration and vitality of plant community in alpine meadows,thus improving their resilience to anthropogenic stress.
基金This work was partially supported by a grant from the Qatar National Research Fund(Grant 5-260-1-053).
文摘Aims To determine if the germination response of desert plant species to a period of aerial storage in field conditions(i.e.mature seeds that remain attached to the parent plant)is comparable to seeds harvested at maturity and stored in ambient laboratory conditions,to better understand the role of aerial seed bank in the germina-tion ecology of desert plants,using one annual and two perennial species.Methods Seeds of three desert plants(Anastatica hierochuntica,Blepharis ciliaris and Scrophularia deserti)that matured in June 2014,were collected from wild plants in June and November 2014,and ger-minated under two photoperiods(0,12 hours light)and three ther-moperiods(night/day temperatures of 15/25,20/30 and 25/35°c).Important Findings Seeds of B.ciliaris and S.deserti had significantly higher germination percentages when harvested and stored for five months,compared to being stored in the aerial seed bank.Germination percentages of these two species increased with decreasing temperature and in the presence of light.These results indicate that these species use a com-bination of aerial and soil seed banks to maintain a percentage of viable seeds through favourable germination periods.Germination percentages of A.hierochuntica were high under all tested circum-stances,indicating that this species relies mainly on the aerial seed bank to maintain a percentage of viable seeds through favourable germination periods.This study shows that the population survival strategies of an aerial seed bank are species-specific.These results have practical implications for conservation and habitat restoration for these species,and also for their propagation since early collec-tion of mature fruits and ex situ storage will result in greater germi-nation percentages of some species.
