Exploring new links between phosphoinositides and phytohormone signaling in Arabidopsis thaliana

磷脂酰肌醇（PI）与植物激素的整合是不明确的。PI和PI衍生的肌醇多磷酸（IP）的变化与生长素（IAA）或茉莉酸（JA）的变化一致，在响应重力刺激和创伤，表明PI的行动在IAA和JA信号级联。最近发现的肌醇六磷酸（InsP 6）辅因子的生长素受体，TIR 1，建议的作用，IP的功能TIR 1或相关的JA受体蛋白，COI 1。这是拟议的工作的目标，以阐明PI衍生的信号分子如何有助于植物激素受体功能。在PI信号传导的不同方面受损的拟南芥野生型植物和转基因系将通过A）向重力性和B）机械损伤刺激，并记录生理反应。将通过微阵列方法研究应激诱导的转录物变化，以描绘具有依赖或不依赖于TIR 1或COI 1的信号传导功能的PI。PI，IAA，JA或其他植物激素的模式的变化将进行系统的生化分析和使用荧光报告。将在存在或不存在InsP 6的情况下在体内测试TIR 1和COI 1与其各自的转录阻遏物Aux/IAA或JAZ的相互作用。TIR 1和COI 1中的InsP 6配位残基将根据TIR 1晶体结构和突变互补试验中检测功能的工程蛋白质进行改变。PI在IAA或JA信号传导中的参与将在植物发育期间进行交叉测试以确定相关性。

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.