National Key Laboratory of Crop Genetics and Germplasm Enhancement, Cytogenetics Institute, Nanjing Agricultural University, Nanjing, Jiangsu 210095, China.
Proc Natl Acad Sci U S A. 2011 May 10;108(19):7727-32. doi: 10.1073/pnas.1016981108. Epub 2011 Apr 20.
Powdery mildew resistance gene Pm21, located on the chromosome 6V short arm of Haynaldia villosa and transferred to wheat as a 6VS·6AL translocation (T6VS·6AL), confers durable and broad-spectrum resistance to wheat powdery mildew. Pm21 has become a key gene resource for powdery mildew resistance breeding all over the world. In China, 12 wheat varieties containing Pm21 have been planted on more than 3.4 million hectares since 2002. Pm21 has been intractable to molecular genetic mapping because the 6VS does not pair and recombine with the 6AS. Moreover, all known accessions of H. villosa are immune to powdery mildew fungus. Pm21 is still defined by cytogenetics as a locus. In the present study, a putative serine and threonine protein kinase gene Stpk-V was cloned and characterized with an integrative strategy of molecular and cytogenetic techniques. Stpk-V is located on the Pm21 locus. The results of a single cell transient expression assay showed that Stpk-V could decrease the haustorium index dramatically. After the Stpk-V was transformed into a susceptible wheat variety Yangmai158, the characterized transgenic plants showed high and broad-spectrum powdery mildew resistance similar to T6VS·6AL. Silencing of the Stpk-V by virus-induced gene silencing in both T6VS·6AL and H. villosa resulted in their increased susceptibility. Stpk-V could be induced by Bgt and exogenous H(2)O(2), but it also mediated the increase of endogenous H(2)O(2), leading to cell death and plant resistance when the plant was attacked by Bgt.
抗白粉病基因 Pm21 位于节节麦 6V 染色体短臂上，作为 6VS·6AL 易位（T6VS·6AL）被导入小麦，赋予小麦对白粉病的持久和广谱抗性。Pm21 已成为全世界白粉病抗性育种的关键基因资源。在中国，自 2002 年以来，已有 12 个含有 Pm21 的小麦品种种植了 340 多万公顷。由于 6VS 与 6AS 不配对和重组，Pm21 一直难以进行分子遗传作图。此外，所有已知的节节麦品系对白粉病真菌都具有免疫性。Pm21 仍然通过细胞遗传学定义为一个基因座。本研究采用分子和细胞遗传学技术的综合策略，克隆和鉴定了一个假定的丝氨酸-苏氨酸蛋白激酶基因 Stpk-V。Stpk-V 位于 Pm21 基因座上。单细胞瞬时表达分析的结果表明，Stpk-V 可以显著降低吸器指数。将 Stpk-V 转化为感病小麦品种扬麦 158 后，鉴定的转基因植株表现出与 T6VS·6AL 相似的高广谱白粉病抗性。通过病毒诱导的基因沉默沉默 Stpk-V 在 T6VS·6AL 和节节麦中均导致其易感性增加。Stpk-V 可以被 Bgt 和外源 H2O2 诱导，但它也介导内源 H2O2 的增加，当植物受到 Bgt 攻击时，导致细胞死亡和植物抗性。
