Leaf blight disease of sunflower caused by Alternaria species is one of the major foliar diseases occurring in sunflower cultivated areas of India. Leaf blight samples collected from sunflower growing areas during rainy season were colonized by Alternariaster helianthi while samples collected during spring season incited by Alternaria alternata. Among two Alternaria species, A. helianthi was the predominant pathogen among the isolates. A total of 220 A. helianthi isolates; 30 A. alternata isolates collected during 2009–10 to 2011–12 from infected sunflower leaves in nine states of India were characterized based on phenotypic, molecular and pathogenic aggressiveness. Molecular identification based on phylogenic analysis using partial internal transcribed spacer regions showed that A. helianthi and A. alternata isolates separated into 11 phylogenetic groups. The pathogenicity on sunflower cultivars KBSH-1, KBSH-44, DRSF-108, PI-535890, TX-16R, Morden revealed that some A. helianthi isolates were highly aggressive with blighting on Morden and DRSF-108. Based on aggressiveness on sunflower cultivars, four groups identified in A. helianthi isolates; three groups in A. alternata isolates. There was no association between phylogenetic group, disease severity and geography of collection among the isolates. Isolates Ah-15, 38, 47, 48, 49, 50, 97, 98, 99, 100, 107, 108, 109, 110, 111, 112, 125 and 126 in A. helianthi; Aa-3, 7, 4 and 9 in A. alternata were aggressive on sunflower cultivars which would be utilized in future disease screening programmes. This is the first report on population structure of Alternaria species and also highlights that A. helianthi is the predominant pathogen associated with sunflower leaf blight in India.

中文翻译：

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印度引起向日葵（Helianthus annuus L.）叶枯病的链格孢属种群结构

由链格孢属植物引起的向日葵叶枯病是印度向日葵种植区发生的主要叶面病害之一。在雨季从向日葵种植区收集的叶枯病样本被 Alternariaster helianthi 定殖，而在春季收集的样本被 Alternaria alternata 激发。在两个链格孢属物种中，向日葵是分离株中的主要病原体。总共 220 株向日葵分离株；2009-10 至 2011-12 年期间，从印度九个州受感染的向日葵叶子中收集的 30 株 A.alternata 分离株基于表型、分子和致病侵袭性进行了表征。基于使用部分内部转录间隔区的系统发育分析的分子鉴定表明，向日葵和 A. 交替链球菌分离物分为 11 个系统发育组。向日葵栽培品种 KBSH-1、KBSH-44、DRSF-108、PI-535890、TX-16R、Morden 的致病性表明，一些向日葵分离株具有高度侵袭性，对 Morden 和 DRSF-108 有枯萎病。基于对向日葵品种的攻击性，在 A. helianthi 分离株中鉴定了四个组；A. alternata 分离株中的三个组。分离株之间的系统发育组、疾病严重程度和收集地理之间没有关联。在向日葵中分离 Ah-15、38、47、48、49、50、97、98、99、100、107、108、109、110、111、112、125 和 126；A. alternata 中的 Aa-3、7、4 和 9 对向日葵品种具有攻击性，这些品种将用于未来的疾病筛查计划。这是关于链格孢属物种种群结构的第一份报告，也强调了 A.