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MOLECULAR GENETIC ANALYSIS OF THE REGULATORY MECHANISM OF POLYAMINE-DEPENDENT STEM ELONGATION IN HIGHER PLANTS

高等植物多胺依赖性茎伸长调控机制的分子遗传学分析

基本信息

批准号：
17370023
负责人：
TAKAHASHI Taku
金额：
$ 9.78万
依托单位：
Okayama University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2005
资助国家：
日本
起止时间：
2005 至 2007
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-17370023/
关键词：
ARABLDOPSIS POLYAMINE DEVELOPMENT MUTANT MOLECULAR GENETICS

项目摘要

Disruption of the Arabidopsis thaliana ACAULIS5 (ACL5) gene results in a severe dwarf phenotype. To elucidate ACL5-mediated regulatory pathways of the stem growth, we isolated four suppressor of acaulis (sac) mutants that reverse the dwarf phenotype. Our results revealed that the sac51-d mutation disrupts a short upstream open reading frame (uORF) of SAC51, which encodes a putative transcription factor and suggested that ACL5 plays a role in translational activation of SAC51.A gene responsible for sac52-d was found to encode a ribosomal protein RPL10A.We also identified three genes in the moss P. patens which are homologous to ACL5.Furthermore, to examine whether ACL5 encodes spermine synthase or thermospermine synthase, we tried to detect these polyamines in plant extracts. The results revealed that thermospermine is detected in wild-type seedlings but is not detectable in the ac15-1 mutant. We further examined the effect of exogenous application of these isomers on the growth of ac15-1. Daily application of thermospermine onto the shoot apex partially rescued the dwarf phenotype of ac15-1, while that of spermine had no effects on the morphology of the mutant. The ac15-1 transcript level in ac15-1 seedlings, which is much higher than the ACL5 transcript level in wild-type seedlings, was found to be reduced by thermospermine. Thus it was concluded that thermospermine is produced through the action of ACL5 and required for stem elongation in Arabidopsis.On the other hand, physiological studies on the mutant of SPMS, which encodes spermine synthase, revealed that spermine plays a protective role in drought and high salt stress responses. These results should provide a important due in understanding the action of polyamines in plant growth and development.

拟南芥ACAULIS5 （ACL5）基因的破坏导致严重的矮化表型。为了阐明acl5介导的茎生长调控途径，我们分离了四种逆转矮化表型的acaulis（囊）抑制突变体。我们的研究结果表明，SAC51 -d突变破坏了SAC51的上游短开放阅读框（uORF），该框架编码一个假定的转录因子，并表明ACL5在SAC51的翻译激活中起作用。一个负责sac52-d的基因被发现编码一种核糖体蛋白RPL10A。我们还在苔藓中发现了3个与ACL5同源的基因。此外，为了研究ACL5是否编码精胺合酶或热精胺合酶，我们试图检测植物提取物中的这些多胺。结果显示，在野生型幼苗中检测到热精胺，而在ac15-1突变体中检测不到。我们进一步研究了外源施用这些异构体对ac15-1生长的影响。每天在茎尖上施用热精胺可以部分恢复ac15-1的矮化表型，而精胺对突变体的形态没有影响。研究发现，热精胺降低了ac15-1幼苗的ac15-1转录水平，而ac15-1幼苗的ACL5转录水平远高于野生型幼苗。由此得出结论，热精胺是通过ACL5的作用产生的，是拟南芥茎伸长所必需的。另一方面，对编码精胺合成酶的SPMS突变体的生理研究表明，精胺在干旱和高盐胁迫响应中起保护作用。这些结果为了解多胺在植物生长发育中的作用提供了重要依据。