Exploring new links between phosphoinositides and phytohormone signaling in Arabidopsis thaliana

磷酸肌苷（PIs）与植物激素的整合是不明确的。在对重刺激和损伤的反应中，pi和pi衍生的肌醇多磷酸（IPs）的变化与生长素（IAA）或茉莉酸（JA）的变化一致，表明pi在IAA-和JA-信号级联反应中都起作用。最近发现的生长素受体TIR1的肌醇己基磷酸（InsP6）辅助因子表明，IPs在TIR1或相关ja受体蛋白COI1的功能中起作用。这是提出的工作的目标，阐明如何提取信号分子有助于植物激素受体的功能。拟南芥野生型植物和转基因系在pi信号的不同方面受到A)向地性和B)机械伤害的刺激，并记录生理反应。胁迫诱导的转录物变化将通过微阵列方法进行研究，以描述具有依赖或独立于TIR1或COI1的信号功能的pi。PIs， IAA， JA或其他植物激素的变化模式将被系统地生化分析和使用荧光报告。TIR1和COI1与其各自的转录抑制因子Aux/IAA或JAZ的相互作用将在体内测试是否存在InsP6。在TIR1和COI1中协调InsP6的残基将根据TIR1的晶体结构和在突变体互补试验中测试功能的工程蛋白而改变。PIs参与IAA-或ja -信号转导将在植物发育过程中进行交叉测试。

The integration of phosphoinositides (PIs) with plant phytohormones is illdefined. Changes in PIs and PI-derived inositolpolyphosphates (IPs) coincide with changes in auxin (IAA) or jasmonate (JA) during responses to gravistimulation and wounding, suggesting that PIs act in both IAA- and JA-signaling cascades. The recent discovery of an inositolhexakisphosphate (InsP6) cofactor of the auxin receptor, TIR1, suggests a role for IPs in the function of TIR1 or the related JA-receptor protein, COI1. It is the goal of the proposed work to elucidate how PIderived signaling molecules contribute to phytohormone receptor function. Arabidopsis wild type-plants and transgenic lines compromised in different aspects of PI-signaling will be stimulated by A) gravitropism and B) mechanical wounding, and physiological responses will be recorded. Stress-induced transcript changes will be investigated by a microarray approach to delineate PIs with signaling functions dependent or independent of TIR1 or COI1. Changes in the patterns of PIs, IAA, JA or other phytohormones will be systematically analyzed biochemically and using fluorescent reporters. TIR1 and COI1 interactions with their respective transcriptional repressors, Aux/IAA or JAZ, will be tested in vivo in the presence or absence of InsP6. Residues coordinating InsP6 in TIR1 and COI1 will be changed based on the TIR1 crystal structure and the engineered proteins tested for functionality in mutant complementation assays. The involvement of PIs in IAA- or JA-signaling will be cross-tested for relevance during plant development.