辣椒霜霉病病原鉴定

Identification of the pathogen causing downy mildew on pepper

辣椒(Capsicum annuum L.)为茄科(Solanace-ae)辣椒属一年生或有限多年生草本植物,是一种重要的蔬菜作物,可作为蔬菜直接食用,也可作为制作辣椒酱、辣椒油和辣椒素等的原料,具有极高的营养和经济价值。湖南是中国的辣椒主产区之一,据统计,2019年湖南辣椒种植面积达12.04万hm2,总产量322.10万t,占全国辣椒总产量的5%,辣椒消费量占全国总消费量的10%以上[1]。随着辣椒产业的迅速发展,特别是漂浮育苗技术及辣椒的连茬种植,辣椒叶部病害为害逐年加重,对我国辣椒产量增长和品质提高均造成了严重威胁。2021年对湖南省长沙市宁乡县的辣椒漂浮育苗基地进行病害调查,发现几乎全部辣椒苗叶片都呈现出疑似霜霉病症状。该病害主要为害叶片,发病初期叶面呈现浅褐色水浸状病斑,多由叶缘开始侵染(图1-A),病斑扩展受叶脉限制,叶背面病斑对应处偶有稀疏灰白色霉层(图1-B);发病中期叶斑颜色加深,由褐变黑(图1-C),叶背面可观察到明显浅灰色霉层(图1-D);发病后期叶片向上卷曲变形,极易脱落(图1-E、F)。通常植株上部叶片先发病,且发病较重(图1-E)。

Pepper(Capsicum annuum L.),belonging to the Solanaceae family,is an economically important vegetable crop in China.In April 2021,severe downy mildew-like symptoms were observed on pepper in Ningx-iang County,Changsha City,Hunan Province.The diseased pepper plants exhibited large,interveinal chlorotic lesions on the adaxial surface of the leaves,which coalesced and turned necrotic as disease progressed.Mean-while,white to gray mycelia could be seen on the abaxial side.Based on morphological characteristics,rDNA-ITS and cox2 sequence analysis,and the result of pathogenicity test,the pathogen was identified as Peronospora capsici.This is the first report of downy mildew caused by P.capsici on pepper in Hunan Province,China,and the sequence information of P.capsici was for the first time deposited in the NCBI nucleotide database.