Kang S, Sweigard J A, Valent B
E. I. du Pont de Nemours and Co. Inc., Wilmington, DE 19880-0402, USA.
Mol Plant Microbe Interact. 1995 Nov-Dec;8(6):939-48. doi: 10.1094/mpmi-8-0939.
The PWL2 gene, isolated from a Magnaporthe grisea rice pathogen, prevents this fungus from infecting a second host grass, weeping lovegrass. We have investigated the distribution of sequences homologous to PWL2 in M. grisea strains isolated from diverse grass species. Multiple PWL2 homologs with varying degrees of sequence homology were identified. The presence of PWL2 homologs does not correlate with an avirulent phenotype on weeping lovegrass in many cases: some strains were fully pathogenic on weeping lovegrass although they carry multiple PWL2 homologs. Three weakly hybridizing PWL2 homologs were cloned and characterized. One of these, the PWL1 gene previously identified by genetic analysis, functioned to prevent infection of weeping lovegrass. Cloned PWL3 and PWL4 genes were nonfunctional, although PWL4 became functional if its expression was driven by either the PWL1 or the PWL2 promoter. The PWL1, PWL2, and PWL3/PWL4 genes map to different genomic locations. The amino acid sequences of the predicted PWL1, PWL3, and PWL4 proteins have 75, 51, and 57% identity, respectively, to the PWL2 protein. Our studies indicate that PWL genes are members of a dynamic, rapidly evolving gene family.
从稻瘟病菌中分离出的PWL2基因可阻止这种真菌感染另一种寄主禾本科植物——垂穗画眉草。我们研究了从不同禾本科植物分离出的稻瘟病菌株中与PWL2同源序列的分布情况。鉴定出了多个具有不同程度序列同源性的PWL2同源物。在许多情况下，PWL2同源物的存在与对垂穗画眉草的无毒表型并无关联：一些菌株尽管携带多个PWL2同源物，但对垂穗画眉草仍具有完全致病性。克隆并鉴定了三个弱杂交的PWL2同源物。其中之一是先前通过遗传分析鉴定出的PWL1基因，其功能是阻止对垂穗画眉草的感染。克隆的PWL3和PWL4基因无功能，不过如果PWL4的表达由PWL1或PWL2启动子驱动，它就会变得有功能。PWL1、PWL2和PWL3/PWL4基因定位于不同的基因组位置。预测的PWL1、PWL3和PWL4蛋白的氨基酸序列与PWL2蛋白的同一性分别为75%、51%和57%。我们的研究表明，PWL基因是一个动态、快速进化的基因家族的成员。
