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ABI5/ABF互作蛋白(AFPs)的过度表达导致了种子对ABA的极端抗性，并导致种子无法获得脱水耐性，至少部分是通过对染色质修饰的影响。本研究验证了AFPs也作为泛素化ABI5的E3连接酶的接头，从而促进萌发的假设。利用酵母双杂交、双分子荧光互补和遗传分析等方法，研究了两类针对ABI5、DWD HYPERSENSITIVE TO ABA (DWA)s和KEEP ON GOING (KEG)的E3连接酶与AFPs的相互作用。虽然AFPs和E3连接酶表现出弱的直接相互作用，但E3连接酶功能的丧失并不影响YFP-AFP2融合过表达所带来的aba抗性。ABI5和AFP2水平的比较表明，在萌发过程中，AFP2的积累增加，但ABI5的降解随着萌发而发生，表明AFP2在萌发过程中控制ABA的敏感性，而不依赖于ABI5的降解。令人惊讶的是，AFP2在dwa1 dwa2突变体背景下的过表达产生了极端的ABA抗性和脱水耐性的不寻常组合，这为我们通过定量蛋白质组学研究分离ABA敏感性和脱水耐性的潜在生化特征创造了机会。我们的分析鉴定了至少比以前的研究多三倍的差异积累的种子蛋白。 通过对不同基因型的干种子蛋白质组的比较，我们可以分离和细化与干旱耐受性相关的蛋白质积累模式的变化，而不依赖于ABA敏感性，或者反过来与寒冷诱导和防御胁迫反应的蛋白质和信号调节因子的亚群相关。 Overexpression of ABI5/ABF interacting proteins (AFPs) results in extreme ABA resistance of seeds and failure to acquire desiccation tolerance, at least in part through effects on chromatin modification. This study tests the hypothesis that the AFPs promote germination by also functioning as adapters for E3 ligases that ubiquitinate ABI5, leading to its degradation. Interactions between AFPs and two well-characterized classes of E3 ligases targeting ABI5, DWD HYPERSENSITIVE TO ABA (DWA)s and KEEP ON GOING (KEG), were analyzed by yeast two-hybrid, bimolecular fluorescence complementation, and genetic assays. Although the AFPs and E3 ligases showed weak direct interactions, loss of function for the E3 ligases did not impair ABA-resistance conferred by overexpression of the YFP-AFP2 fusion. Comparison of ABI5 and AFP2 levels in these lines showed that AFP2 accumulation increased during germination, but that ABI5 degradation followed germination, demonstrating that AFP2 controls ABA sensitivity during germination independently of ABI5 degradation. Surprisingly, AFP2 overexpression in the dwa1 dwa2 mutant background produced the unusual combination of extreme ABA resistance and desiccation tolerance, creating an opportunity to separate the underlying biochemical characteristics of ABA sensitivity and desiccation tolerance that we investigated by quantitative proteomics. Our analysis identified at least three-fold more differentially accumulated seed proteins than previous studies. Comparison of dry seed proteomes of the different genotypes allowed us to separate and refine the changes in protein accumulation patterns correlating with desiccation tolerance independently of ABA sensitivity, or vice versa, to a subset of cold-induced and defense stress-responsive proteins and signaling regulators.  文章来源网络整理；如有侵权请及时联系PaperRSS小编删除，转载请注明来源。 温馨提示： 为方便PaperRSS粉丝们科研、就业等话题交流。我们根据10多个专业方向（植物、医学、药学、人工智能、化学、物理、财经管理、体育等），特建立了30个国内外博士交流群。群成员来源欧美、日韩、新加坡、清华北大、中科院等全球名校。 |
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