ARAG1，一个 ABA 响应的 DREB 基因，在水稻种子萌发和抗旱性中发挥作用。
ARAG1, an ABA-responsive DREB gene, plays a role in seed germination and drought tolerance of rice.
机构信息
Research Center for Molecular & Developmental Biology, Key Laboratory of Photosynthesis & Environmental Molecular Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China.
出版信息
Ann Bot. 2010 Mar;105(3):401-9. doi: 10.1093/aob/mcp303. Epub 2010 Jan 24.
BACKGROUND AND AIMS
DREB proteins are involved mainly in plant responses to abiotic stresses such as cold, drought or high salinity as well as ABA signalling. However, the function of most rice DREB genes and the underlying molecular mechanisms controlling these responses remains elusive. In this study, ARAG1, a rice DREB gene, was functionally analysed.
METHODS
Antisense and over-expression constructs of ARAG1 were introduced into rice by an Agrobacterium-mediated method. RT-PCR and western blot were used to detect ARAG1 accumulation in transgenics. PEG and ABA were used to test their response to abiotic stresses.
KEY RESULTS
ARAG1 was expressed in inflorescences, roots, immature embryos and germinating seeds, but not in coleoptiles, leaves or mature embryos. Drought stress and ABA treatment increased transcript levels of the gene rapidly. ARAG1 knockdown line was hypersensitive to ABA application during seed germination and seedling growth. However, the line over-expressing ARAG1 behaved similarly to wild type in these circumstances. Knockdown of ARAG1 weakened tolerance of the transgenic seedlings to drought stress, while over-expression of it increased the tolerance slightly. In addition, activity of alpha-amylases was enhanced in germinating seeds of the knockdown and over-expression lines.
CONCLUSIONS
These results indicate that ARAG1 was involved in the ABA signalling and stress responsive pathways.
背景与目的
DREB 蛋白主要参与植物对非生物胁迫的反应，如寒冷、干旱、高盐以及 ABA 信号转导。然而，大多数水稻 DREB 基因的功能及其对这些反应的调控的分子机制仍不清楚。本研究对水稻 DREB 基因 ARAG1 进行了功能分析。
方法
通过农杆菌介导的方法将 ARAG1 的反义及过表达载体导入水稻中。利用 RT-PCR 和 Western blot 检测转基因中 ARAG1 的积累情况。利用 PEG 和 ABA 检测其对非生物胁迫的响应。
结果
ARAG1 在花序、根、未成熟胚和萌发种子中表达，但在幼叶、叶片和成熟胚中不表达。干旱胁迫和 ABA 处理能迅速增加基因的转录水平。ARAG1 敲低系在种子萌发和幼苗生长过程中对 ABA 处理表现出超敏性。然而，过表达系在这些情况下表现出与野生型相似的行为。ARAG1 敲低削弱了转基因幼苗对干旱胁迫的耐受性，而过表达则略微提高了其耐受性。此外，敲低系和过表达系萌发种子中的α-淀粉酶活性增强。
结论
这些结果表明，ARAG1 参与了 ABA 信号转导和应激响应途径。
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