转录因子LcEIL2/3调控荔枝果实脱落机制研究

EIN3/EIL是乙烯信号传导途径的关键转录因子，至今尚无EIN3/EIL转录调控器官脱落机制方面的报道。针对荔枝生产中存在的严重落果问题，本项目拟从EIN3/EIL转录因子直接调控细胞壁水解酶下游靶基因和反馈调节乙烯生物合成途径的新视角，来揭示乙烯调控器官落果分子机制。前期工作已初步筛选出与荔枝果实脱落相关的EIN3/EIL转录因子2 个（LcEIL2/3）及其候选靶基因12个。先通过比较分析落果程度不同品种间、同一品种不同促进和抑制落果处理间等对比样品中LcEIL2/3转录因子及其候选靶基因表达及细胞壁水解酶活性等生理指标变化，验证LcEIL2/3及其候选靶基因与落果关系；后采用EMSA等DNA-蛋白互作技术，确定LcEIL2/3调控的下游靶基因，并通过异源转基因和VIGS技术，双向验证LcEIL2/3在荔枝果实脱落中的功能。研究结果为理解器官脱落分子机制和改进荔枝防落措施提供新依据。

Phytohormone ethylene is a strong organ abscission stimulator. However, as the important transcription factor of ethylene signal transduction pathway, the role of EIN3/EIL is still unclear during organ abscission. Litchi (Litchi chinensis Sonn.), as the important and specific tropical fruit crop, has severe fruit abscission. Therefore, this project will explore the molecular regulatory mechanism of ethylene, focusing on EIN3/EIL TFs directly regulating the cell wall remodeling genes and ethylene biosynthesis genes. Based on previously study, two EIN3/EIL TFs (LcEIL2 and LcEIL3) and twelve target genes (seven cell wall remodeling genes and five ethylene biosynthesis genes) are identified to be involved in litchi fruitlet abscission. We plan to perform different promoting and inhibiting fruit abscission treatments in same cultivar and compare different cultivars with different degree of fruit drop under normal condition. Then, analyzing the expression of LcEIL2/3 and the target genes, the production of ethylene, and the activity of cell wall hydrolase during above-mentioned treatments aim to identify the role of LcEIL2/3 and target genes during litchi fruitlet abscission. Further, ectopic gene transformation, VIGS, EMSA and other experiments will be performed to examine the function and the molecular regulatory mechanism of LcEIL2/3. Collectively, the results will provide new insights and evidences for exploring the molecular mechanism of organ abscission in plants and improving measures to reduce fruit abscission in litchi.