油菜素内酯诱导桃果实采后抗病的效果及作用机制研究

Brassinosteroids (BRs) is a class of plant growth substances that are widely distributed in plant. BRs has shown good induced resistant effect on a variety of crops and fruits. But it stays to be unclear about its effects and mechanism of prevention and control of postharvest diseases on peach fruits. This project will select peach fruits as the research object, with the treatment of BRs induction, and analyze its induced resistant effect, and then choose the best conditions for BRs induction treatment and clone BZR1 gene. Subsequently, use yeast two hybrid system to screen WRKY transcription factors that interact with BZR1, then verify their interactions with pull-down assay. Clone the WRKY transcription factor genes, and then detect the expression of these WRKY genes. At the same time, identify the target factors functioning downstream of these WRKY transcription factors. Then analyze the key mediating factors in BRs induced disease resistance pathways, and demonstrate the mechanisms of BRs induced disease resistance. This project will provide a scientific basis for the development and application of BRs induced resistance in fruit postharvest storage.

油菜素内酯 (BRs) 是一类广泛存在于植物中的生长调节物质，在多种作物上都表现出较好的诱导抗病效果, 但其对桃果实采后病害防控的效果及其作用机理尚不清楚。本项目以桃果实为研究对象，通过油菜素内酯诱导处理，分析其诱导抗病效果，获得油菜素内酯诱导处理的最佳条件,克隆BRs信号通路中关键因子BZR1基因。同时，利用酵母双杂交筛选得到与BZR1互作的WRKY类转录因子，并利用pull-down assay加以验证，进而对WRKY类转录因子基因进行克隆、并对其表达情况进行检测、对WRKY转录因子下游的靶标因子进行鉴定，以分析油菜素内酯诱导抗病通路中的关键介导因子，解析油菜素内酯诱导桃果实抗病性产生的作用机理。本项目研究将为油菜素内酯诱导抗病技术在果实采后保鲜中的开发和应用提供科学依据。

本项目以桃果实为研究对象，通过油菜素内酯诱导处理，筛选出油菜素内酯诱导处理的最佳浓度为10mmol/L；研究发现，油菜素内酯处理桃果实能够降低桃采后褐腐病的发病率，并显著抑制果实的病斑扩展，同时，BRs诱导H2O2和总酚的积累，诱导几丁质酶、β-1,3-葡聚糖酶和POD、PAL等抗病相关酶活性的上升。荧光定量PCR检测表明，油菜素内酯处理显著诱导了PpNPR1-like，PpPR1-like，CHI，GNS，PAL等抗病相关基因的表达；通过酵母双杂交和Pull-down assay筛选验证，油菜素内酯信号通路中重要调控因子BZR1和3个WRKY类转录因子存在互作关系。以上结果表明，油菜素内酯抑制桃采后褐腐病的机理是诱导了桃果实的抗病性，本项目的研究结果将为油菜素内酯诱导抗病技术在果实采后保鲜中的开发和应用提供科学依据。此外，在本项目的资助下，项目组还进行了果实采后病害防治的其他相关研究。