ABSTRACT

Peronophythora litchii (P. litchii) is the pathogenic factor of litchi downy blight. Derivatives extracted from harmine officinalis and modified, N-(2-pyridyl)-1-phenyl-9 H-pyrido [3, 4-b] indole-3-formamide (PPPIF), could inhibited P. litchii growth and development. Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) analyses indicated that PPPIF severely damaged the mitochondria, cell wall and endomembrane system of P. litchii cells, thus abnormal morphology, as well as deformed mycelia. PPPIF could suppress mycelial growth, sporulation, sporangia germination and germ tube elongation as well. PPPIF also caused a series of physiological and biochemical changes of P. litchii, including the serious deviation of extracellular pH, the obvious increase of the content of extracellular reducing sugar and malondialdehyde, the notable decrease of soluble protein and the activity of NADH oxidase. Furthermore, PPPIF seriously raised openness of membrane permeability transporter (MPTP) and markedly decreased the transmembrane potential (Δψm) and the activity of enzyme complex I–complex V in respiratory chain of mitochondria. The current research suggests that PPPIF may act upon the mitochondrion of P. litchii, then respiratory chain complex activity was blocked and energy metabolism disrupted or inhibited, resulting in the growth inhibition of P. litchii. Above results have strengthened our understanding of P. litchii resistance mechanisms and may help in the development of more potent inhibitors against plant diseases in the fields.

摘要

荔枝霜霉病（P. litchii ）是荔枝霜霉病的致病因子。从harmine officinalis 中提取的衍生物和修饰的N-(2-pyridyl)-1-phenyl-9 H-pyrido [3, 4-b] indole-3-formamide (PPPIF) 可以抑制P. litchii的生长和发育。扫描电镜（SEM）和透射电镜（TEM）分析表明，PPPIF严重破坏了荔枝菌细胞的线粒体、细胞壁和内膜系统，导致形态异常，菌丝体变形。PPPIF还可以抑制菌丝生长、孢子形成、孢子囊萌发和胚管伸长。PPPIF还引起了荔枝的一系列生理生化变化,包括胞外pH值严重偏离,胞外还原糖和丙二醛含量明显升高,可溶性蛋白明显降低,NADH氧化酶活性明显下降。此外，PPPIF显着提高了膜通透性转运蛋白（MPTP）的开放性，显着降低了线粒体呼吸链中的跨膜电位（Δψm）和酶复合物I-复合物V的活性。目前的研究表明，PPPIF可能作用于荔枝的线粒体，使呼吸链复合物的活性受阻，能量代谢受到干扰或抑制，从而导致荔枝的生长受到抑制。以上结果加强了我们对P. litchii的认识抗机制，并可能有助于开发更有效的针对田间植物病害的抑制剂。