A gain-of-function mutation in IAA8 alters Arabidopsis floral organ development by change of jasmonic acid level
A gain-of-function mutation in IAA8 alters Arabidopsis floral organ development by change of jasmonic acid level
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DOI：
10.1007/s11103-013-0039-y
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发表时间：
2013-03
影响因子：
5.1
通讯作者：
Jing Wang;Da-wei Yan;Ting-Ting Yuan-Ting;Xiang Gao;Ying‐Tang Lu
中科院分区：
文献类型：
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作者：
Jing Wang;Da-wei Yan;Ting-Ting Yuan-Ting;Xiang Gao;Ying‐Tang Lu
生长素通过其下游因子Aux/IAAs调节多种生理过程。本研究以IAA 8启动子调控下的GFP-mIAA 8转基因植株为材料，通过将IAA 8蛋白的保守结构域II中的Pro 170突变为Leu 170，证明IAA 8在拟南芥发育中发挥重要作用。这些转基因矮化植株侧枝多，主花序茎短，茎尖优势下降，叶片卷曲，花器官异常（短花瓣和雄蕊，弯曲柱头）。进一步的实验表明，IAA 8：：GFP-mIAA 8植株可能通过稳定IAA 8蛋白抵抗蛋白酶体介导的蛋白质降解而增加GFP-mIAA 8的表达量，而IAA 8：：GFP-IAA 8植株作为对照。对IAA 8下游因子的研究表明，IAA 8与ARF 6和ARF 8均存在相互作用，提示IAA 8可能参与了花器官的发育。通过分析茉莉酸（JA）生物合成基因的表达和JA水平进一步证明了这一点，因为正常JA生产需要ARF 6和ARF 8。这些结果表明，在IAA 8：：GFP-mIAA 8植株中，JA生物合成基因DAD 1（AT 2G 44810）、AOS（AT 5G 42650）和ORP 3（AT 2G 06050）被显著下调，花中JA水平降低至野生型的70%。此外，外源JA的应用可以部分挽救短花瓣和雄蕊脱落的IAA 8：：GFP-mIAA 8植株。因此，IAA 8可能通过与ARF 6/8蛋白的相互作用，通过JA水平的变化在花器官发育中发挥作用。
Auxin regulates a variety of physiological processes via its downstream factors includedAux/IAAs. In this study, one of theseAux/IAAs,IAA8is shown to play its role inArabidopsisdevelopment with transgenic plants expressing GFP-mIAA8 under the control ofIAA8promoter, in which IAA8 protein was mutated by changing Pro170to Leu170in its conserved domain II. These transgenic dwarfed plants had more lateral branches, short primary inflorescence stems, decreased shoot apical dominance, curled leaves and abnormal flower organs (short petal and stamen, and bent stigmas). Further experiments revealed thatIAA8::GFP-mIAA8plants functioned as gain-of-function mutation to increase GFP-mIAA8 amount probably by stabilizing IAA8 protein against proteasome-mediated protein degradation withIAA8::GFP-IAA8plants as control. The searching for its downstream factors indicated its interaction with both ARF6 and ARF8, suggesting that IAA8 may involve in flower organ development. This was further evidenced by analyzing the expression of jasmonic acid (JA) biosynthetic genes and JA levels becauseARF6andARF8are required for normal JA production. These results indicated that inIAA8::GFP-mIAA8plants, JA biosynthetic genes includingDAD1(AT2G44810),AOS(AT5G42650) andORP3(AT2G06050) were dramatically down-regulated and JA level in the flowers was reduced to 70 % of that in wild-type. Furthermore, exogenous JA application can partially rescue short petal and stamen observedIAA8::GFP-mIAA8plants. Thus, IAA8 plays its role in floral organ development by changes in JA levels probably via its interaction with ARF6/8 proteins.