College of Plant Protection, Nanjing Agricultural University, Nanjing, 210095, China.
Mol Plant Microbe Interact. 2013 Jul;26(7):711-20. doi: 10.1094/MPMI-12-12-0289-R.
Resistance to Phytophthora sojae (Rps) genes have been widely used in soybean against root and stem rot diseases caused by this oomycete. Among 15 known soybean Rps genes, Rps1k has been the most widely used in the past four decades. Here, we show that the products of two distinct but closely linked RxLR effector genes are detected by Rps1k-containing plants, resulting in disease resistance. One of the genes is Avr1b-1, that confers avirulence in the presence of Rps1b. Three lines of evidence, including overexpression and gene silencing of Avr1b-1 in stable P. sojae transformants, as well as transient expression of this gene in soybean, indicated that Avr1b could trigger an Rps1k-mediated defense response. Some isolates of P. sojae that do not express Avr1b are nevertheless unable to infect Rps1k plants. In those isolates, we identified a second RxLR effector gene (designated Avr1k), located 5 kb away from Avr1b-1. Silencing or overexpression of Avr1k in P. sojae stable transformants resulted in the loss or gain, respectively, of the avirulence phenotype in the presence of Rps1k. Only isolates of P. sojae with mutant alleles of both Avr1b-1 and Avr1k could evade perception by the soybean plants carrying Rps1k.
大豆疫霉（Phytophthora sojae）的抗性基因已被广泛用于大豆，以抵抗这种卵菌引起的根和茎腐烂病。在 15 个已知的大豆 Rps 基因中，Rps1k 在过去四十年中被广泛使用。在这里，我们表明，含有 Rps1k 的植物检测到两个不同但紧密连锁的 RxLR 效应子基因的产物，从而导致抗病性。其中一个基因是 Avr1b-1，它在存在 Rps1b 的情况下赋予无毒力。包括 Avr1b-1 在稳定的 P. sojae 转化体中的过表达和基因沉默，以及该基因在大豆中的瞬时表达在内的三条证据表明，Avr1b 可以触发 Rps1k 介导的防御反应。尽管一些不表达 Avr1b 的 P. sojae 分离株仍然无法感染 Rps1k 植物。在这些分离株中，我们鉴定了第二个 RxLR 效应子基因（命名为 Avr1k），它位于 Avr1b-1 之外 5 kb 处。在 P. sojae 稳定转化体中沉默或过表达 Avr1k 分别导致在存在 Rps1k 的情况下丧失或获得无毒力表型。只有同时具有 Avr1b-1 和 Avr1k 突变等位基因的 P. sojae 分离株才能逃避携带 Rps1k 的大豆植物的感知。
