Primary dormancy of seeds of Korean pine(Pinus koraiensis Sieb.et Zucc.)after dispersal in the autumn and the induction of secondary dormancy the fi rst summer following seed dispersal limit the regeneration of mixed ...Primary dormancy of seeds of Korean pine(Pinus koraiensis Sieb.et Zucc.)after dispersal in the autumn and the induction of secondary dormancy the fi rst summer following seed dispersal limit the regeneration of mixed broadleaved Korean pine forests in Northeast China.This study was to determine how changes in the levels of abscisic acid(ABA)and gibberellic acid(GA)maintain primary and secondary dormancy of Korean pine seeds under germination conditions.We transferred seeds with one of fi ve primary dormancy states or three secondary dormancy states to germination conditions and measured changes in the levels of ABA,GA 1+3(GA 1 and GA 3)and GA 4+7(GA 4 and GA 7)in the seed coat,megagametophyte and embryo during incubation.Seed coat ABA levels in primary dormant seeds(PDS)and ABA levels in various parts of secondary dormant seeds(SDS)gradually declined during incubation but were still higher than in seeds for which dormancy was progressively released.GA 4+7 and GA 1+3 levels in embryos greatly decreased 35%and 24%,respectively,during incubation of SDS,and thus,the ratio of ABA to GA 4+7 in embryos and megagametophytes signifi cantly increased.The ratio of ABA to GA 1+3 in various parts of SDS increased slightly during incubation.In contrast,in seeds for which secondary dormancy was already released,GA 4+7 and GA 1+3 levels in the embryo,GA 4+7/ABA ratio in the embryo and seed coat,and the GA 1+3/ABA in the embryo and megagametophyte signifi cantly increased during incubation.There was no trend in the changes in the levels of ABA,GA 4+7 or GA 1+3 in embryos and megagametophytes of PDS or the levels of GA 4+7 or GA 1+3 in megagametophytes of SDS during incubation.The results suggest that high ABA levels in the seed coat maintain primary dormancy of Korean pine seeds.Maintenance of secondary dormancy involves a reduction of GA 4+7,GA 1+3,GA 4+7/ABA,and GA 1+3/ABA and the retention of high ABA levels.展开更多
Basic Leu zipper ( bZIP ) genes play pivotal, versatile roles in abiotic or biotic stress responses and in other biological processes. Knowledge on the evolutionary relationships and patterns of gene expression of bZI...Basic Leu zipper ( bZIP ) genes play pivotal, versatile roles in abiotic or biotic stress responses and in other biological processes. Knowledge on the evolutionary relationships and patterns of gene expression of bZIP family members in woody plants, however, has been limited. Here we identified and characterized 47 BpbZIP genes across the silver birch ( Betula pendula Roth.) genome. With reference to bZIP classifications for Arabidopsis thaliana , all BpbZIP proteins clustered among 10 groups in phylogeny. The bZIP domains were divided into five patterns based on intron positions and splicing phases. A total of 24 conserved motifs were detected in BpbZIPs with high group specificity. We also analyzed the protein structure of the BpAREB/ABF/ ABI5 subfamily, the most important subfamily in the bZIP family. Expression analyses demonstrated that BpbZIP genes were widely involved in abscisic acid, salt, drought, and heat stress responses, with BpbZIP07/ABF4 and BpbZIP21/ABF2 most highly expressed. Our results on genome-wide identification, evolutionary relationships, gene structure, and motif and promoter element identification for BpbZIP family members in silver birch provide a comprehensive understanding of bZIP transcription factors in birch and will lead to a deeper understanding of their evolution and potential biological functions.展开更多
A high-efficiency somatic embryogenesis protocol of Japanese larch （Larix leptolepis Gordon） has been established in our investigation. Calli were induced from immature zygotic embryos of female cones ofL. leptolepi...A high-efficiency somatic embryogenesis protocol of Japanese larch （Larix leptolepis Gordon） has been established in our investigation. Calli were induced from immature zygotic embryos of female cones ofL. leptolepis and then subcultured regularly on to a modified Gupta and Durzan （DCR） basal medium for 5 years. Embryogenic tissues showed distinct morphological changes dur- ing somatic embryo development when they were transferred to a maturation medium supplemented with abscisic acid （ABA） com- pared with the morphology in a medium lacking ABA. Histological observations indicated that polyembryony was a characteristic feature during early embryogeny and somatic embryos at later stages showed normal histodifferentiation. In addition, histochemical analysis revealed that abundant starch granules and proteins accumulated in mature embryos, indicating that they played important roles in the development and regeneration of normal plantlets from somatic embryos on hormone-free germination media展开更多
Elucidating the regulatory mechanisms of environmental factors on seed dormancy and germination will provide guidance for tree regeneration.Toward understanding the coupled effect of light and temperature on dormancy ...Elucidating the regulatory mechanisms of environmental factors on seed dormancy and germination will provide guidance for tree regeneration.Toward understanding the coupled effect of light and temperature on dormancy release and germination of Pinus koraiensis seeds,we set up three light conditions(L200:200μmol m^(-2) s^(-1),L20:20μmol m^(-2) s^(-1),L0:0μm^(-2) s^(-1))and four storage temperatures[T-5:-5°C(50 days),T5:-5°C(50 days)+5°C(50 days),T25:-5°C(50 days)+5°C(50 days)+25°C(50 days),T15:-5°C(50 days)+5°C(50 days)+25°C(50 days)+15°C(50 days)]using imbibed seeds,then quantified phytohormones gibberellic acid(GA_(3))and abscisic acid(ABA)during the stratification.Germination percentage(G_(P)),mean germination time(T_(M)),and germination value(G_(V))under 25/15°C temperature and the three light conditions were then determined.Phytohormone levels and germination performances were significantly affected by light and temperature.No consistent trend was found between the phytohormone levels and G_(P) caused by light levels.Under the three light conditions,ABA concentrations in the embryo and endosperm decreased as storage temperature shifted from T-5 to T25 and increased from T25 to T15;GA_(3) decreased in nearly all four storage temperatures.G_(P) reached 40–60%in T25 storage without light irradiance.In the three light conditions,G_(P) and G_(V) were higher at T5 and T25 than at T-5 and T15;so T5 and T25 are considered as optimum storage temperatures for dormancy release and germination.At optimum temperatures,light(L200,L20)significantly increased the G_(P) and G_(V) compared with the dark(L0).At L200 and L20,significant negative correlations between G_(V) and the ABA concentrations and positive correlations between G_(V) and GA/ABA in the seed embryo were found.Temperature played a more important role in primary dormancy release and germination;light was unnecessary for primary dormancy release.Light facilitated seed germination at optimum temperatures.The dormancy release and germination of P.koraiensis seeds were controlled by a decrease in ABA concentrations or an increase in GA/ABA induced by temperature variations.展开更多
基金We thank Kai Yang and Lizhong Yu and Xiao Zheng and Tao Sun for valuable discussion and suggestions about this study.We also thank Hongjun Xu,Jingpu Zhang,Weiwei Zhang and Shuang Xu for fi eld support and technical assistance.
文摘Primary dormancy of seeds of Korean pine(Pinus koraiensis Sieb.et Zucc.)after dispersal in the autumn and the induction of secondary dormancy the fi rst summer following seed dispersal limit the regeneration of mixed broadleaved Korean pine forests in Northeast China.This study was to determine how changes in the levels of abscisic acid(ABA)and gibberellic acid(GA)maintain primary and secondary dormancy of Korean pine seeds under germination conditions.We transferred seeds with one of fi ve primary dormancy states or three secondary dormancy states to germination conditions and measured changes in the levels of ABA,GA 1+3(GA 1 and GA 3)and GA 4+7(GA 4 and GA 7)in the seed coat,megagametophyte and embryo during incubation.Seed coat ABA levels in primary dormant seeds(PDS)and ABA levels in various parts of secondary dormant seeds(SDS)gradually declined during incubation but were still higher than in seeds for which dormancy was progressively released.GA 4+7 and GA 1+3 levels in embryos greatly decreased 35%and 24%,respectively,during incubation of SDS,and thus,the ratio of ABA to GA 4+7 in embryos and megagametophytes signifi cantly increased.The ratio of ABA to GA 1+3 in various parts of SDS increased slightly during incubation.In contrast,in seeds for which secondary dormancy was already released,GA 4+7 and GA 1+3 levels in the embryo,GA 4+7/ABA ratio in the embryo and seed coat,and the GA 1+3/ABA in the embryo and megagametophyte signifi cantly increased during incubation.There was no trend in the changes in the levels of ABA,GA 4+7 or GA 1+3 in embryos and megagametophytes of PDS or the levels of GA 4+7 or GA 1+3 in megagametophytes of SDS during incubation.The results suggest that high ABA levels in the seed coat maintain primary dormancy of Korean pine seeds.Maintenance of secondary dormancy involves a reduction of GA 4+7,GA 1+3,GA 4+7/ABA,and GA 1+3/ABA and the retention of high ABA levels.
基金The work was supported by the Fundamental Research Funds for the Central Universities of China(2572018CL04)the InnovationProject of State Key Laboratory of Tree Genetics and Breeding(2020A02)the Heilongjiang Touyan Innovation Team Program(Tree Genetics andBreeding Innovation Team).
文摘Basic Leu zipper ( bZIP ) genes play pivotal, versatile roles in abiotic or biotic stress responses and in other biological processes. Knowledge on the evolutionary relationships and patterns of gene expression of bZIP family members in woody plants, however, has been limited. Here we identified and characterized 47 BpbZIP genes across the silver birch ( Betula pendula Roth.) genome. With reference to bZIP classifications for Arabidopsis thaliana , all BpbZIP proteins clustered among 10 groups in phylogeny. The bZIP domains were divided into five patterns based on intron positions and splicing phases. A total of 24 conserved motifs were detected in BpbZIPs with high group specificity. We also analyzed the protein structure of the BpAREB/ABF/ ABI5 subfamily, the most important subfamily in the bZIP family. Expression analyses demonstrated that BpbZIP genes were widely involved in abscisic acid, salt, drought, and heat stress responses, with BpbZIP07/ABF4 and BpbZIP21/ABF2 most highly expressed. Our results on genome-wide identification, evolutionary relationships, gene structure, and motif and promoter element identification for BpbZIP family members in silver birch provide a comprehensive understanding of bZIP transcription factors in birch and will lead to a deeper understanding of their evolution and potential biological functions.
基金the National Natural Science Foundation of China （Grant No. 30471366） the National Science Fund of China for Distinguished Young Scholars （30225005）.
文摘A high-efficiency somatic embryogenesis protocol of Japanese larch （Larix leptolepis Gordon） has been established in our investigation. Calli were induced from immature zygotic embryos of female cones ofL. leptolepis and then subcultured regularly on to a modified Gupta and Durzan （DCR） basal medium for 5 years. Embryogenic tissues showed distinct morphological changes dur- ing somatic embryo development when they were transferred to a maturation medium supplemented with abscisic acid （ABA） com- pared with the morphology in a medium lacking ABA. Histological observations indicated that polyembryony was a characteristic feature during early embryogeny and somatic embryos at later stages showed normal histodifferentiation. In addition, histochemical analysis revealed that abundant starch granules and proteins accumulated in mature embryos, indicating that they played important roles in the development and regeneration of normal plantlets from somatic embryos on hormone-free germination media
基金supported by National Natural Science Foundation of China(No.31830016 and 31800534)。
文摘Elucidating the regulatory mechanisms of environmental factors on seed dormancy and germination will provide guidance for tree regeneration.Toward understanding the coupled effect of light and temperature on dormancy release and germination of Pinus koraiensis seeds,we set up three light conditions(L200:200μmol m^(-2) s^(-1),L20:20μmol m^(-2) s^(-1),L0:0μm^(-2) s^(-1))and four storage temperatures[T-5:-5°C(50 days),T5:-5°C(50 days)+5°C(50 days),T25:-5°C(50 days)+5°C(50 days)+25°C(50 days),T15:-5°C(50 days)+5°C(50 days)+25°C(50 days)+15°C(50 days)]using imbibed seeds,then quantified phytohormones gibberellic acid(GA_(3))and abscisic acid(ABA)during the stratification.Germination percentage(G_(P)),mean germination time(T_(M)),and germination value(G_(V))under 25/15°C temperature and the three light conditions were then determined.Phytohormone levels and germination performances were significantly affected by light and temperature.No consistent trend was found between the phytohormone levels and G_(P) caused by light levels.Under the three light conditions,ABA concentrations in the embryo and endosperm decreased as storage temperature shifted from T-5 to T25 and increased from T25 to T15;GA_(3) decreased in nearly all four storage temperatures.G_(P) reached 40–60%in T25 storage without light irradiance.In the three light conditions,G_(P) and G_(V) were higher at T5 and T25 than at T-5 and T15;so T5 and T25 are considered as optimum storage temperatures for dormancy release and germination.At optimum temperatures,light(L200,L20)significantly increased the G_(P) and G_(V) compared with the dark(L0).At L200 and L20,significant negative correlations between G_(V) and the ABA concentrations and positive correlations between G_(V) and GA/ABA in the seed embryo were found.Temperature played a more important role in primary dormancy release and germination;light was unnecessary for primary dormancy release.Light facilitated seed germination at optimum temperatures.The dormancy release and germination of P.koraiensis seeds were controlled by a decrease in ABA concentrations or an increase in GA/ABA induced by temperature variations.
