Triticeae Research Institute, Sichuan Agricultural University, 211 Huimin Road, Wenjiang, Chengdu, Sichuan, 611130, PR China.
J Exp Bot. 2013 Aug;64(11):3125-36. doi: 10.1093/jxb/ert146.
Calcium-dependent protein kinases (CPKs) are important Ca2+ signalling components involved in complex immune and stress signalling networks; but the knowledge of CPK gene functions in the hexaploid wheat is limited. Previously, TaCPK2 was shown to be inducible by powdery mildew (Blumeria graminis tritici, Bgt) infection in wheat. Here, its functions in disease resistance are characterized further. This study shows the presence of defence-response and cold-response cis-elements on the promoters of the A subgenome homoeologue (TaCPK2-A) and D subgenome homoeologue (TaCPK2-D), respectively. Their expression patterns were then confirmed by quantitative real-time PCR (qRT-PCR) using genome-specific primers, where TaCPK2-A was induced by Bgt treatment while TaCPK2-D mainly responded to cold treatment. Downregulation of TaCPK2-A by virus-induced gene silencing (VIGS) causes loss of resistance to Bgt in resistant wheat lines, indicating that TaCPK2-A is required for powdery mildew resistance. Furthermore, overexpression of TaCPK2-A in rice enhanced bacterial blight (Xanthomonas oryzae pv. oryzae, Xoo) resistance. qRT-PCR analysis showed that overexpression of TaCPK2-A in rice promoted the expression of OsWRKY45-1, a transcription factor involved in both fungal and bacterial resistance by regulating jasmonic acid and salicylic acid signalling genes. The opposite effect was found in wheat TaCPK2-A VIGS plants, where the homologue of OsWRKY45-1 was significantly repressed. These data suggest that modulation of WRKY45-1 and associated defence-response genes by CPK2 genes may be the common mechanism for multiple disease resistance in grass species, which may have undergone subfunctionalization in promoters before the formation of hexaploid wheat.
钙依赖蛋白激酶（CPKs）是参与复杂免疫和应激信号网络的重要 Ca2+信号成分；但六倍体小麦中 CPK 基因功能的知识有限。以前，已经表明 TaCPK2 可被小麦白粉病（Blumeria graminis tritici，Bgt）感染诱导。在这里，进一步研究了其在抗病性中的功能。本研究表明，A 亚基因组同源物（TaCPK2-A）和 D 亚基因组同源物（TaCPK2-D）的启动子上分别存在防御反应和冷响应顺式元件。然后使用基因组特异性引物通过定量实时 PCR（qRT-PCR）证实了它们的表达模式，其中 TaCPK2-A 被 Bgt 处理诱导，而 TaCPK2-D 主要对冷处理作出反应。通过病毒诱导的基因沉默（VIGS）下调 TaCPK2-A 会导致抗白粉病小麦品系丧失抗性，表明 TaCPK2-A 是白粉病抗性所必需的。此外，在水稻中过表达 TaCPK2-A 增强了对细菌性条斑病（Xanthomonas oryzae pv. oryzae，Xoo）的抗性。qRT-PCR 分析表明，在水稻中过表达 TaCPK2-A 通过调节茉莉酸和水杨酸信号基因促进参与真菌和细菌抗性的转录因子 OsWRKY45-1 的表达。在小麦 TaCPK2-A VIGS 植物中发现了相反的效果，其中 OsWRKY45-1 的同源物受到显著抑制。这些数据表明，CPK2 基因对 WRKY45-1 和相关防御反应基因的调节可能是禾本科多种抗病性的共同机制，在六倍体小麦形成之前，该机制可能在启动子中经历了亚功能化。
