白粉菌(Erysiphe graminis)侵染诱导表达的小麦糖苷水解酶基因TaGlc2的克隆与鉴定

真菌病害是世界小麦生产中的最重要的病害之一。目前，在小麦中已经鉴定出一批小麦病菌侵染诱导基因，包括病程相关基因和抗真菌水解酶基因（葡聚糖酶基因和几丁质酶基因）。最近的研究表明，植物1,3-β-葡聚糖酶参与对真菌侵染的防卫。本研究从小麦cDNA文库中克隆出一个编码小麦1,3-β-葡聚糖酶的新基因，命名为 TaGlc2。该基因编码的氨基酸序列与糖苷水解酶基因家族17高度同源。采用实时定量PCR分析方法对TaGlc2基因在白粉菌侵染(Erysiphe graminis)后小麦叶片中的表达模式进行研究，发现TaGlc2基因在白粉菌侵染6 h后表达明显增强，至24 h达到峰值，说明该基因受白粉菌侵染诱导表达。还获得了TaGlc2基因5'上游调控区序列，发现存在与病菌侵染响应有关的顺式元件。小麦TaGlc2基因在小麦白粉病抗性上可能具有重要作用。

Cloning and Characterization of a Novel Wheat Glycoside Hydrolase Gene TaGlc2 Induced by Powdery Mildew Pathogen (Erysiphe graminis) Infection

Fungal diseases cause serious yield losses of wheat worldwide. Up to date, numerous genes involved in the wheat-pathogen response have been identified. These include pathogenesis related (PR) genes and antifungal hydrolases such as glucanase and chitinase genes. Recently, there has been increasing number of studies providing evidence of the potential involvement of 1,3-β-glucanase in defense against fungal infection. In this study we identified a cDNA encoding a 1,3-β-glucanase, designated TaGlc2, from wheat cDNA library. The deduced peptide sequence of TaGlc2 is similar to a glycoside hydrolase family 17. Using real time PCR, the expression pattern of TaGlc2 in wheat seedlings inoculated with powdery mildew pathogen (Erysiphe graminis) was determined. The results showed that TaGlc2 is inducible in response to fungal infection. The 5'' genomic region of TaGlc2 was isolated and it contains some cis-elements which are reported to be involved in pathogenesis response.