Fu Yanping, Duan Xiaoyuan, Tang Chunlei, Li Xiaorui, Voegele Ralf T, Wang Xiaojie, Wei Guorong, Kang Zhensheng
State Key Laboratory of Crop Stress Biology for Arid Areas and College of Life Sciences, Northwest A&F University, Yangling, Shaanxi, 712100, China.
Plant J. 2014 Apr;78(1):16-30. doi: 10.1111/tpj.12457. Epub 2014 Mar 12.
The actin cytoskeleton is involved in plant defense responses; however, the role of the actin-depolymerizing factor (ADF) family, which regulates actin cytoskeletal dynamics, in plant disease resistance, is largely unknown. Here, we characterized a wheat (Triticum aestivum) ADF gene, TaADF7, with three copies located on chromosomes 1A, 1B, and 1D, respectively. All three copies encoded the same protein, although there were variations in 19 nucleotide positions in the open reading frame. Transcriptional expression of the three TaADF7 copies were all sharply elevated in response to avirulent Puccinia striiformis f. sp. tritici (Pst) infection, with similar expression patterns. TaADF7 regulated the actin cytoskeletal dynamics by targeting the actin cytoskeleton to execute actin binding/severing activities. When the TaADF7 copies were all silenced by virus-induced gene silencing, the growth of Pst hypha increased and sporadic urediniospores were observed, as compared with control plants, upon inoculation with avirulent Pst. In addition, the accumulation of reactive oxygen species (ROS) and the hypersensitive response (HR) were greatly weakened, whereas cytochalasin B partially rescued the HR in TaADF7 knock-down plants. Together, these findings suggest that TaADF7 is likely to contribute to wheat resistance against Pst infection by modulating the actin cytoskeletal dynamics to influence ROS accumulation and the HR.
肌动蛋白细胞骨架参与植物防御反应；然而，调节肌动蛋白细胞骨架动态的肌动蛋白解聚因子（ADF）家族在植物抗病性中的作用在很大程度上尚不清楚。在此，我们鉴定了一个小麦（Triticum aestivum）ADF基因TaADF7，它有三个拷贝，分别位于1A、1B和1D染色体上。尽管开放阅读框中有19个核苷酸位置存在变异，但所有三个拷贝编码的都是相同的蛋白质。三个TaADF7拷贝的转录表达在响应无毒的条锈菌（Puccinia striiformis f. sp. tritici，Pst）感染时均急剧升高，且表达模式相似。TaADF7通过靶向肌动蛋白细胞骨架来执行肌动蛋白结合/切断活性，从而调节肌动蛋白细胞骨架动态。当通过病毒诱导的基因沉默使TaADF7的所有拷贝均沉默时，与对照植株相比，接种无毒Pst后观察到Pst菌丝生长增加且出现散生的夏孢子。此外，活性氧（ROS）的积累和超敏反应（HR）大大减弱，而细胞松弛素B部分挽救了TaADF7基因敲低植株中的HR。总之，这些发现表明TaADF7可能通过调节肌动蛋白细胞骨架动态来影响ROS积累和HR，从而有助于小麦抵抗Pst感染。
