Faculty of Business, Hannan University, Matsubara 580-8502, Japan.
Mol Plant Pathol. 2005 Nov 1;6(6):605-13. doi: 10.1111/j.1364-3703.2005.00309.x.
SUMMARY Culture filtrates from 72 isolates of Pyricularia, grouped into 13 rDNA types, were analysed via HPLC. Of these isolates, 31 (r9 DNA type) from crabgrass (Digitaria sanguinalis), one (r9 DNA type) from pangolagrass (Digitaria smutsii) and six (r8 DNA type) from Digitaria horizontalis produced 20-280 microg pyrichalasin H per millilitre of culture. These same isolates were pathogenic on five Digitaria species. Interestingly, two isolates, KM-1 and Br 29, which were originally isolated from Digitaria plants, did not produce pyrichalasin H, nor caused blast lesion on Digitaria plants. Because these two isolates were identified as Digitaria pathogens by PCR analysis using Digitaria-specific primers, they are likely to be mutants lacking pyrichalasin H production. Isolates that belonged to the remaining 11 rDNA types did not produce pyrichalasin H and were avirulent to Digitaria plants. Therefore, the virulence of Pyricularia on Digitaria plants correlates with pyrichalasin H production. Pyrichalasin H was also present in spore germination fluid of a crabgrass isolate (IBDS 5-1-1), but not in that of isolates from rice, foxtail millet, finger millet, common millet and wheat. In addition, pyrichalasin H was detected in host leaves infected with IBDS 5-1-1, but not in leaves from other plants infected with compatible Pyricularia isolates. Pretreatment of leaf sheaths of crabgrass with 3 microg/mL pyrichalasin H led to the penetration and colonization by non-host isolates. Overall, these results indicate that production of pyrichalasin H is responsible for the genus-specific pathogenicity of Digitaria isolates.
从 72 个 Pyricularia 分离株的培养滤液中通过 HPLC 进行分析，这些分离株分为 13 种 rDNA 类型。其中 31 株（r9 DNA 型）来自稗草（Digitaria sanguinalis），1 株（r9 DNA 型）来自野黍（Digitaria smutsii），6 株（r8 DNA 型）来自多年生狗尾草（Digitaria horizontalis），每毫升培养物中产生 20-280 微克的 Pyrichalasin H。这些相同的分离株对 5 种狗尾草物种具有致病性。有趣的是，两个分离株，KM-1 和 Br 29，最初是从狗尾草植物中分离出来的，没有产生 Pyrichalasin H，也没有在狗尾草植物上引起病害斑。由于这两个分离株通过使用狗尾草特异性引物的 PCR 分析被鉴定为狗尾草病原体，它们可能是缺乏 Pyrichalasin H 产生的突变体。属于其余 11 种 rDNA 类型的分离株没有产生 Pyrichalasin H，对狗尾草植物没有毒力。因此，Pyricularia 对狗尾草植物的毒力与 Pyrichalasin H 的产生相关。Pyrichalasin H 也存在于稗草分离株（IBDS 5-1-1）的孢子萌发液中，但不存在于来自水稻、谷子、画眉草、黍和小麦的分离株中。此外，在感染 IBDS 5-1-1 的寄主叶片中检测到 Pyrichalasin H，但在感染其他 Pyricularia 分离株的叶片中未检测到。用 3μg/mL Pyrichalasin H 预处理稗草叶鞘会导致非寄主分离株穿透和定植。总的来说，这些结果表明 Pyrichalasin H 的产生是狗尾草分离株属特异性致病性的原因。
