Virginia Bioinformatics Institute, Virginia Polytechnic Institute and State University Blacksburg 24061, USA.
Mol Plant Microbe Interact. 2010 Apr;23(4):425-35. doi: 10.1094/MPMI-23-4-0425.
At least 12 avirulence genes have been genetically identified and mapped in Phytophthora sojae, an oomycete pathogen causing root and stem rot of soybean. Previously, the Avr4 and Avr6 genes of P. sojae were genetically mapped within a 24 kb interval of the genome. Here, we identify Avr4 and Avr6 and show that they are actually a single gene, Avr4/6, located near the 24-kb region. Avr4/6 encodes a secreted protein of 123 amino acids with an RXLR-dEER protein translocation motif. Transient expression of Avr4/6 in soybean leaves revealed that its gene product could trigger a hypersensitive response (HR) in the presence of either Rps4 or Rps6. Silencing Avr4/6 in P. sojae stable transformants abolished the avirulence phenotype exhibited on both Rps4 and Rps6 soybean cultivars. The N terminus of Avr4/6, including the dEER motif, is sufficient to trigger Rps4-dependent HR while its C terminus is sufficient to trigger Rps6-mediated HR. Compared with alleles from avirulent races, alleles of Avr4/6 from virulent races possess nucleotide substitutions in the 5' untranslated region of the gene but not in the protein-coding region.
至少有 12 个无毒基因已在卵菌病原菌大豆疫霉中被鉴定和定位，该病原菌可引起大豆的根和茎腐烂。先前，大豆疫霉的 Avr4 和 Avr6 基因已在基因组的 24kb 间隔内进行了遗传定位。在这里，我们鉴定了 Avr4 和 Avr6，并表明它们实际上是一个单一基因，Avr4/6，位于 24kb 区域附近。Avr4/6 编码一个 123 个氨基酸的分泌蛋白，具有 RXLR-dEER 蛋白转运基序。Avr4/6 在大豆叶片中的瞬时表达表明，其基因产物在存在 Rps4 或 Rps6 的情况下可以触发过敏反应 (HR)。在大豆疫霉菌稳定转化体中沉默 Avr4/6 会消除其在 Rps4 和 Rps6 大豆品种上的无毒表型。Avr4/6 的 N 端，包括 dEER 基序，足以触发依赖于 Rps4 的 HR，而其 C 端足以触发 Rps6 介导的 HR。与无毒种群的等位基因相比，来自毒力种群的 Avr4/6 等位基因在基因的 5'非翻译区具有核苷酸取代，但在蛋白编码区没有核苷酸取代。
