防控香蕉枯萎病的芳基吡咯杀菌剂导向化改造及其内吸输导性

Fusarium wilt of banana is one of the most destructive fungal disease which significantly threatens the sustainable development of the banana industry in China. Traditional systemic fungicides are difficult to reach the site of target--the vascular tissues of banana duo to lacking of tissue targeting, and therefore chemical control has been found to be ineffective in the field. This project is plan to modify the chemical structure of fungicide based on ion-trap mechanism and carrier-mediated transport of amino acids. The project includes (1) The chemical structure of non-systemic fungicide fludioxonil, which showed excellent fungicidal activity, will be modified by introducing carboxylic acid group or amino acid moiety, and the fungicidal activity of conjugates will be evaluated; (2) Using foliar application, corm injection and soil drenching, a contrastive study of guided fludioxonil conjugates and the traditional systemic fungicide carbendazim will be conducted to investigate the translocation and distribution of compounds in banana leave, pseudostem, rhizome and roots, as well as to study the transportation dose and direction of guided fludioxonil conjugates; (3) The screened fludioxonil conjugates which show good mobility and fungicidal activity will be further test in greenhouse assessment using optimal application method. The purpose of this project is to achieve the targeted translocation and accumulation of guided fungicides in banana, thus providing a new approach to develop the fungicides against vascular diseases.

香蕉枯萎病是一种威胁我国香蕉产业可持续发展的毁灭性病害。传统内吸性杀菌剂由于缺乏组织靶向性无法有效到达病原菌为害部位——香蕉维管组织，所以田间防治效果不佳。本项目拟基于“离子井”效应和氨基酸转运蛋白介导两种植物韧皮部装载机制对现有杀菌剂进行导向化改造。项目计划（1）对前期研究表明具有良好抑菌活性的芳基吡咯非内吸杀菌剂咯菌腈进行化学修饰，构建含有羧基或氨基酸导向基团的偶合物并研究导向基团引入对抑菌活性的影响；（2）通过涂叶，球茎注射和灌根三种施药方式，以传统内吸性杀菌剂多菌灵为对照，对比研究导向咯菌腈偶合物在香蕉叶、假茎、球茎和根中的输导分布规律，明确两类导向杀菌剂的输导剂量与移动方向；（3）对兼具活性和输导性的化合物采用最佳施药方式进行室内盆栽药效试验。项目将探索能在香蕉体内定向输导与积累的导向杀菌剂，为防治维管组织病害的杀菌剂研发提供新的思路。

香蕉枯萎病是一种威胁我国香蕉产业可持续发展的毁灭性病害。作为一种系统性维管组织病害，由于现有内吸性杀菌剂缺乏在维管组织内的定向积累，导致有效成分难以到达为害部位，最终田间化学防效不佳。为解决香蕉枯萎病化学防治难题，本研究选择对香蕉枯萎病菌具有良好抑菌活性的芳基吡咯非内吸杀菌剂咯菌腈为活性母体，基于植物韧皮部“离子井”效应和氨基酸转运蛋白介导两种策略，研发具有韧皮部传导性的导向咯菌腈杀菌剂，旨在通过韧皮部导向传递进行维管组织靶向给药，实现对香蕉枯萎病的化学防治。主要研究结果如下：. 基于“离子井”效应，对咯菌腈分子进行弱酸化修饰，在咯菌腈吡咯环仲胺基上引入羧酸基团，构建了羧酸咯菌腈偶合物3个、羧酸酯偶合物4个；蓖麻幼苗韧皮部输导实验证明了羧酸基团引入使原本无韧皮部输导性的咯菌腈具有了韧皮部输导性，并验证存在“离子井”效应机制；香蕉盆栽试验表明，羧酸偶合物JG-A1在被叶片吸收后能向下传递到植株球茎和根部，并能降解释放母体化合物咯菌腈，从而在盆栽防效测定中表现出54.5%的防效。. 基于氨基酸转运蛋白介导策略，在咯菌腈吡咯环仲胺基上引入了6种氨基酸分子，分别构建了6个氨基酸偶合物和6个氨基酸酯偶合物；通过蓖麻幼苗筛选到缬氨酸偶合物WDD15和缬氨酸酯偶合物WDD13具有最佳的韧皮部输导性；结合室内毒理测定结果，研究了具有最佳活性的缬氨酸酯偶合物WDD13在香蕉植株体内的输导分布。结果表明，偶合物WDD13在被叶片吸收后，在香蕉体内表现出了双向输导能力，药剂能向下传导到球茎和根，在第5天时在香蕉球茎达到峰值浓度0.28μmol/L。. 两种策略均能成功改善咯菌腈的韧皮部输导性，实现向地下为害部位的积累，不仅为维管组织导向杀菌剂研发奠定基础，也为维管组织病害化学防治提供新思路。目前共发表学术论文3篇，其中SCI论文1篇，中文核心期刊论文1篇，国内会议论文1篇，获得发明专利1项。