ABSTRACT

Phytopythium is a globally distributed genus, species of which occur in various ecological niches. Despite their importance as plant pathogens, information on species diversity and their distribution in West Azarbaijan Province of Iran is limited. This study aimed to investigate the taxonomy and plant pathogenicity of Phytopythium isolates recovered from soils in the province. A polyphasic taxonomy based on morphological, cultural, and multilocus sequence data revealed two new species, described here as P. babaiaharii and P. longitubum. In addition, a putatively new species and five known species, P. boreale, P. carbonicum, P. mercuriale, P. ostracodes, and P. vexans, were found in the studied region. Phytopythium ostracodes, P. mercuriale, and P. boreale were the three most frequent species isolated from soil, although P. mercuriale was only found in one field. Among the studied species, P. mercuriale, P. ostracodes, and P. vexans exhibited various levels of pathogenicity on sugar beet, sunflower, and tomato, and P. boreale was documented for first time as a plant pathogen. Phytopythium ostracodes was highly aggressive on sugar beet and sunflower but lowly aggressive on tomato, whereas P. vexans exhibited high aggressiveness toward the three crop plants. Both P. boreale and P. mercuriale were found to be lowly aggressive on the host plants. The results indicated that members of Phytopythium, particularly plant-pathogenic species, are common in arable soils of West Azarbaijan Province and can pose a threat to agricultural crops in the region.

摘要

Phytopythium是一个全球分布的属，其物种出现在各种生态位中。尽管它们作为植物病原体很重要，但有关物种多样性及其在伊朗西阿塞拜疆省分布的信息是有限的。本研究旨在调查从该省土壤中回收的植霉菌属分离株的分类学和植物致病性。基于形态、文化和多位点序列数据的多相分类法揭示了两个新物种，这里称为P. babaiaharii和P. longitubum。此外，还有一个推定的新物种和五个已知物种，即P.boreale、P. carbonicum、P. mercuriale、P. ostracodes和P. vexans, 在研究区域被发现。Phytopythium介形类化石，P. mercuriale和P. boreale是从土壤中分离的三个最常见的品种，虽然P. mercuriale在一个场才发现。在所研究的物种，P. mercuriale，P.介形类，和P.刺扰伊蚊显示对糖用甜菜，向日葵，番茄致病性的各种等级，并且P. boreale被记录为第一次作为植物病原体。Phytopythium ostracodes对甜菜和向日葵具有很强的攻击性，但对番茄的攻击性较低，而P. vexans对三种作物表现出很高的攻击性。两个P.boreale和P. mercuriale被发现对寄主植物的攻击性较低。结果表明，Phytopythium 的成员，特别是植物致病物种，在西阿塞拜疆省的耕地土壤中很常见，可能对该地区的农作物构成威胁。