Tiller angle of rice （Oryza sativa L.） is an important agronomic trait that contributes to grain production, and has long attracted attentions of breeders for achieving ideal plant architecture to improve grain yiel...Tiller angle of rice （Oryza sativa L.） is an important agronomic trait that contributes to grain production, and has long attracted attentions of breeders for achieving ideal plant architecture to improve grain yield. Although enormous efforts have been made over the past decades to study mutants with extremely spreading or compact tillers, the molecular mechanism underlying the control of tiller angle of cereal crops remains unknown. Here we report the cloning of the LAZY1 （LA1） gene that regulates shoot gravitropism by which the rice tiller angle is controlled. We show that LA1, a novel grass-specific gene, is temporally and spatially expressed, and plays a negative role in polar auxin transport （PAT）. Loss-of-function of LA1 enhances PAT greatly and thus alters the endogenous IAA distribution in shoots, leading to the reduced gravitropism, and therefore the tiller-spreading phenotype of rice plants.展开更多
Polyamines are implicated in regulating various developmental processes in plants, but their exact roles and how they govern these processes still remain elusive. We report here an Arabidopsis bushy and dwarf mutant, ...Polyamines are implicated in regulating various developmental processes in plants, but their exact roles and how they govern these processes still remain elusive. We report here an Arabidopsis bushy and dwarf mutant, bud2, which results from the complete deletion of one member of the small gene family that encodes S-adenosylmethionine decarboxylases （SAMDCs） necessary for the formation of the indispensable intermediate in the polyamine biosynthetic pathway. The bud2 plant has enlarged vascular systems in inflorescences, roots, and petioles, and an altered homeostasis ofpolyamines. The double mutant of bud2 and samdcl, a knockdown mutant of another SAMDC member, is embryo lethal, demonstrating that SAMDCs are essential for plant embryogenesis. Our results suggest that polyamines are required for the normal growth and development of higher plants.展开更多
The ratio of auxin and cytokinin plays a crucial role in regulating aerial architecture by promoting or repressing axillary bud outgrowth. We have previously identified an Arabidopsis mutant bud2 that displays altered...The ratio of auxin and cytokinin plays a crucial role in regulating aerial architecture by promoting or repressing axillary bud outgrowth. We have previously identified an Arabidopsis mutant bud2 that displays altered root and shoot architecture, which results from the loss-of-function of S-adenosylmethionine decarboxylase 4 （SAMDC4）. In this study, we demonstrate that BUD2 could be induced by auxin, and the induction is dependent on auxin signaling. The mutation of BUD2 results in hyposensitivity to auxin and hypersensitivity to cytokinin, which is confirmed by callus induction assays. Our study suggests that polyamines may play their roles in regulating the plant architecture through affecting the homeostasis of cytokinins and sensitivities to auxin and cytokinin.展开更多
基金grants from the Ministry of Science and Technology of China(2005CB 1208)the National Natural Science Foundation of China(30330040 and 30570161).
文摘Tiller angle of rice （Oryza sativa L.） is an important agronomic trait that contributes to grain production, and has long attracted attentions of breeders for achieving ideal plant architecture to improve grain yield. Although enormous efforts have been made over the past decades to study mutants with extremely spreading or compact tillers, the molecular mechanism underlying the control of tiller angle of cereal crops remains unknown. Here we report the cloning of the LAZY1 （LA1） gene that regulates shoot gravitropism by which the rice tiller angle is controlled. We show that LA1, a novel grass-specific gene, is temporally and spatially expressed, and plays a negative role in polar auxin transport （PAT）. Loss-of-function of LA1 enhances PAT greatly and thus alters the endogenous IAA distribution in shoots, leading to the reduced gravitropism, and therefore the tiller-spreading phenotype of rice plants.
基金We thank Dr Senya Matsufuji(Jikei University,Japan)for providing the yeast spe2 strain,Dr Guixian Xia(Institute of Microbiology,Chinese Academy of Sciences,China)for yeast expression vector pREP5N and ABRC stock center for BAC clones(F17K4 and T16G12)and T-DNA insertion lines(Salk_007279 and Salk_020185).This work was supported by grants from National Natural Science Foundation of China(30330040)the Ministry of Sciences and Technology of China(J02-A-001).
文摘Polyamines are implicated in regulating various developmental processes in plants, but their exact roles and how they govern these processes still remain elusive. We report here an Arabidopsis bushy and dwarf mutant, bud2, which results from the complete deletion of one member of the small gene family that encodes S-adenosylmethionine decarboxylases （SAMDCs） necessary for the formation of the indispensable intermediate in the polyamine biosynthetic pathway. The bud2 plant has enlarged vascular systems in inflorescences, roots, and petioles, and an altered homeostasis ofpolyamines. The double mutant of bud2 and samdcl, a knockdown mutant of another SAMDC member, is embryo lethal, demonstrating that SAMDCs are essential for plant embryogenesis. Our results suggest that polyamines are required for the normal growth and development of higher plants.
基金We thank Dr Ottoline Leyser （University of York, UK） for providing axrl-3 and Dr Mark Estelle （UC, San Diego, USA） for providing tirlafb2afb3 triple mutant seeds. This work was supported by a grant from the National Natural Science Foundation of China （30830009）.
文摘The ratio of auxin and cytokinin plays a crucial role in regulating aerial architecture by promoting or repressing axillary bud outgrowth. We have previously identified an Arabidopsis mutant bud2 that displays altered root and shoot architecture, which results from the loss-of-function of S-adenosylmethionine decarboxylase 4 （SAMDC4）. In this study, we demonstrate that BUD2 could be induced by auxin, and the induction is dependent on auxin signaling. The mutation of BUD2 results in hyposensitivity to auxin and hypersensitivity to cytokinin, which is confirmed by callus induction assays. Our study suggests that polyamines may play their roles in regulating the plant architecture through affecting the homeostasis of cytokinins and sensitivities to auxin and cytokinin.
