Niu Ji-Shan, Zhang Li-Na, Wang Ying-Hong, Hong De-Feng
National Center of Engineering and Technological Research for Wheat, Henan Agricultural University, Zhengzhou 450002, China.
Zhi Wu Sheng Li Yu Fen Zi Sheng Wu Xue Xue Bao. 2006 Feb;32(1):79-86.
To investigate whether homologs of wheat (Triticum aestivum L.) LRK10 gene was expressed in powdery mildew-resistant lines after inoculation with Blumeria graminis f. sp. tritici, one degenerate primer for 5'-RACE was designed according to the 6th kinase subdomain of LRK10 and other plant kinases. 5'-RACE was performed with the template cDNA synthesized with RNA extracted from seedling leaves of a powdery mildew-resistant wheat line "99-2439" after inoculation with B. graminis. One 1551 bp cDNA fragment representing a protein kinase gene was obtained (S1125, GenBank accession number: AY584533). Subsequently, a 2255-bp full-length cDNA clone with a complete encoding region (open reading frame, ORF) was obtained by RACE. The clone encodes a polypeptide consisting of 637 amino acid residues. The result of homology search showed that it belongs to a receptor-like kinase gene family in wheat, which was named as wlrk (wheat leaf rust kinase) previously. Similar to LRK10, this protein kinase has five distinct domains: a hydrophobic signal sequence at the amino-terminus, a putative extracellular domain, a transmembrane domain, a highly charged sequence and a serine/threonine kinase domain at the carboxy-terminus, and thus it was named as TaLRK (Triticum aestivum LRK). The expression pattern of TaLRK at transcription level in leaves after B. graminis infection was investigated by semi-quantitative RT-PCR (semi-QRT-PCR), using wheat actin gene as a control. The result showed that the transcription of TaLRK was significantly enhanced by B. graminis infection. The expression pattern of TaLRK in different tissues showed that this new wheat RLK gene was expressed only in green parts of wheat. This study suggests that TaLRK may function in wheat powdery mildew resistance responses.
为了研究小麦（Triticum aestivum L.）LRK10基因的同源物在接种小麦白粉病菌（Blumeria graminis f. sp. tritici）后是否在抗白粉病品系中表达，根据LRK10的第6个激酶亚结构域以及其他植物激酶，设计了一个用于5'-RACE的简并引物。以接种小麦白粉病菌后的抗白粉病小麦品系“99-2439”幼苗叶片提取的RNA合成的模板cDNA进行5'-RACE。获得了一个1551 bp的代表蛋白激酶基因的cDNA片段（S1125，GenBank登录号：AY584533）。随后，通过RACE获得了一个具有完整编码区（开放阅读框，ORF）的2255 bp全长cDNA克隆。该克隆编码一个由637个氨基酸残基组成的多肽。同源性搜索结果表明，它属于小麦中的一个类受体激酶基因家族，此前被命名为wlrk（小麦叶锈病激酶）。与LRK10类似，这种蛋白激酶有五个不同的结构域：氨基端的疏水信号序列、假定的细胞外结构域、跨膜结构域、高电荷序列以及羧基端的丝氨酸/苏氨酸激酶结构域，因此将其命名为TaLRK（Triticum aestivum LRK）。以小麦肌动蛋白基因作为对照，通过半定量RT-PCR（semi-QRT-PCR）研究了TaLRK在小麦白粉病菌感染后叶片转录水平的表达模式。结果表明，小麦白粉病菌感染显著增强了TaLRK的转录。TaLRK在不同组织中的表达模式表明，这个新的小麦RLK基因仅在小麦的绿色部分表达。本研究表明，TaLRK可能在小麦抗白粉病反应中发挥作用。
