Emami Kaveh, Hack Ethan
Department of Biological and Nutritional Sciences, University of Newcastle, Newcastle upon Tyne, NE1 7RU UK.
Curr Microbiol. 2002 Oct;45(4):303-6. doi: 10.1007/s00284-002-3618-8.
Two types of xylanase gene, XYN11A ( XYL1) and XYN11B ( XYL2), were amplified by PCR and partially sequenced in four phytopathogenic species of the ascomycete fungal genus Cochliobolus (anamorph genus Bipolaris). Three of the species, C. heterostrophus ( B. maydis), C. sativus ( B. sorokiniana), and Bipolaris sorghicola (no teleomorph known), are interrelated; the fourth, C. spicifer ( B. spicifera), was found, through analysis of the 5.8S RNA and internal transcribed spacer (ITS) sequences of its ribosomal DNA, to be more distantly related to the other three. Isolates from all four species contain orthologous XYN11A and XYN11B genes, but a set of laboratory strains of C. heterostrophus gave no product corresponding to the XYN11B gene. The patterns of evolution of the two xylanase genes and ribosomal DNA sequences are mutually consistent; the results indicate that the two genes were present in the common ancestor of all Cochliobolus species and are evolving independently of each other.
通过聚合酶链反应（PCR）扩增了两种木聚糖酶基因XYN11A（XYL1）和XYN11B（XYL2），并对子囊菌真菌属旋孢腔菌属（无性型属为离蠕孢属）的四个植物病原物种进行了部分测序。其中三个物种，即异旋孢腔菌（玉米离蠕孢）、燕麦旋孢腔菌（禾谷离蠕孢）和高粱离蠕孢（尚无已知的有性型）是相互关联的；通过对其核糖体DNA的5.8S RNA和内部转录间隔区（ITS）序列进行分析，发现第四个物种，即尖孢旋孢腔菌（尖孢离蠕孢）与其他三个物种的亲缘关系更远。来自所有四个物种的分离株都含有直系同源的XYN11A和XYN11B基因，但一组异旋孢腔菌的实验室菌株未产生与XYN11B基因对应的产物。两种木聚糖酶基因和核糖体DNA序列的进化模式相互一致；结果表明，这两个基因存在于所有旋孢腔菌物种的共同祖先中，并且彼此独立进化。
