Zhang Yonghong, Qu Zhipeng, Zheng Wenming, Liu Bo, Wang Xiaojie, Xue Xiaodan, Xu Liangsheng, Huang Lili, Han Qingmei, Zhao Jie, Kang Zhensheng
College of Plant Protection and Shaanxi Key Laboratory of Molecular Biology for Agriculture, Northwest A&F University, Yangling, Shaanxi, 712100, PR China.
BMC Genomics. 2008 May 1;9:203. doi: 10.1186/1471-2164-9-203.
Puccinia striiformis f. sp. tritici is an obligate biotrophic pathogen that causes leaf stripe rust on wheat. Although it is critical to understand molecular mechanisms of pathogenesis in the wheat stripe rust fungus for developing novel disease management strategies, little is known about its genome and gene functions due to difficulties in molecular studies with this important pathogen. To identify genes expressed during early infection stages, in this study we constructed a cDNA library with RNA isolated from urediniospores of P. striiformis f. sp. tritici germinated for 10 h.
A total of 4798 ESTs were sequenced from the germinated urediniospore library and assembled into 315 contigs and 803 singletons. About 23.9% and 13.3% of the resulting 1118 unisequences were homologous to functionally characterized proteins and hypothetical proteins, respectively. The rest 62.8% unisequences had no significant homologs in GenBank. Several of these ESTs shared significant homology with known fungal pathogenicity or virulence factors, such as HESP767 of the flax rust and PMK1, GAS1, and GAS2 of the rice blast fungus. We selected six ESTs (Ps28, Ps85, Ps87, Ps259, Ps261, and Ps159) for assaying their expression patterns during urediniospore germination and wheat infection by quantitative real-time PCR. All of them had the highest transcript level in germinated urediniospores and a much less transcript level in un-germinated urediniospores and infected wheat tissues (1-7 dpi). The transcript level of Ps159 increased at later infection stages (6-7 dpi). Our data indicated that these genes were highly expressed in germinated urediniospores and may play important roles in fungal-plant interactions during early infection stages in the wheat stripe rust fungus.
Genes expressed in germinated urediniospores of P. striiformis f. sp. tritici were identified by EST analysis. Six of them were confirmed by quantitative real-time PCR assays to be highly expressed in germinated urediniospores.
条形柄锈菌小麦专化型是一种活体营养型专性病原菌，可引起小麦条锈病。尽管了解小麦条锈菌的致病分子机制对于制定新的病害管理策略至关重要，但由于对这种重要病原菌进行分子研究存在困难，其基因组和基因功能鲜为人知。为了鉴定早期感染阶段表达的基因，在本研究中，我们用从小麦条锈菌夏孢子萌发10小时后分离的RNA构建了一个cDNA文库。
从萌发的夏孢子文库中总共测序了4798条EST，并组装成315个重叠群和803个单拷贝序列。在所得的1118个单序列中，分别约有23.9%和13.3%与功能已鉴定的蛋白质和假定蛋白质同源。其余62.8%的单序列在GenBank中没有显著同源物。其中一些EST与已知的真菌致病性或毒力因子有显著同源性，如亚麻锈菌的HESP767以及稻瘟病菌的PMK1、GAS1和GAS2。我们选择了6个EST（Ps28、Ps85、Ps87、Ps259、Ps261和Ps159），通过定量实时PCR分析它们在夏孢子萌发和小麦感染过程中的表达模式。它们在萌发的夏孢子中均具有最高转录水平，而在未萌发的夏孢子和感染的小麦组织（接种后1 - 7天）中的转录水平则低得多。Ps159的转录水平在感染后期（接种后6 - 7天）有所增加。我们的数据表明，这些基因在萌发的夏孢子中高度表达，可能在小麦条锈菌早期感染阶段的真菌 - 植物相互作用中发挥重要作用。
通过EST分析鉴定了小麦条锈菌夏孢子萌发过程中表达的基因。其中6个基因经定量实时PCR分析证实在萌发的夏孢子中高度表达。
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