论文信息：Bo Wang , Xiaofei Liang, Mark L. Gleason, Rong Zhang, and Guangyu Sun. Comparative genomics of Botryosphaeria dothidea and B. kuwatsukai, causal agents of apple ring rot, reveals both species expansion of pathogenicity-related genes and variations in virulence gene content during speciation. IMA Fungus, 2018, 9(2): 243-257.
JCR分区Q2，IF=4.308
苹果轮纹病是一种世界性病害，病害分布广，在亚洲、美洲、欧洲、澳洲、非洲等地均有发生。中国主要苹果产区均有发生,高温多雨的东部地区严重时可造成50%-60%烂果率，给我国苹果产业经济带来巨大损失。前期研究发现，苹果轮纹病由两种不同病原，葡萄座腔菌（Botryosphaeria dothidea）和粗皮葡萄座腔菌（B. kuwatsukai.）引起。两种病原菌在系统演化、致病性、寄主范围、生物特性等方面都存在显著差异（Fungal Diversity：2015），但造成这些差异的机理尚不清楚。该研究通过比较基因组分析发现，两种病原菌大约在247万年前分化成不同种类；与葡萄座腔菌科其他种类相比，两病原菌的致病菌基因数量远超过同科的其他种，说明它们可能经历了第二轮基因组支系扩张；发现葡萄座腔菌基因组中，与植物侵染互作所相关细胞壁降解酶、次级代谢合成相关基因、分泌型肽酶等，明显多于粗皮葡萄座腔菌，这可能是葡萄座腔菌寄主范围广、致病性强的重要原因。该研究全面的解析了两病原菌进化方向、物种形成及致病性差异可能机制，为进一步研究该类真菌与寄主互作、育种、防治策略制定提供了指引。
葡萄座腔菌和粗皮葡萄座腔菌同源性与系统基因组关系
论文摘要：Ring rot, one of the most destructive diseases of apple worldwide, is caused primarily by Botryosphaeria dothidea and B. kuwatsukai. Here, we sequenced the genomes of B. dothidea strain PG45 (44.3 Mb with 5.12 % repeat rate) and B. kuwatsukai epitype strain PG2 (48.0 Mb with 13.02 % repeat rate), and conducted a comparative analysis of these two genomes, as well as other sequenced fungal genomes, in order to understand speciation and distinctive patterns of evolution of pathogenicity-related genes. Pair-wise genome alignments revealed that the two species are highly syntenic (96.74 % average sequence identity). Both species encode a significant number of pathogenicity-related genes, e.g. carbohydrate active enzymes (CAZYs), plant cell wall degrading enzymes (PCWDEs), secondary metabolites (SMs) biosynthetic enzymes, cytochrome P450 enzymes (CYPs), and secreted peptidases, in comparison to all additional sequenced fungal species involved in various life-styles. The number of pathogenicity-related genes in B. dothidea and B. kuwatsukai is higher than other genomes of Botryosphaeriaceae pathogens (Macrophomina phaseolina and Neofusicoccum parvum), suggesting a secondary round of Botryosphaeria-lineage expansion in the family. There were, however, also significant differences in the genomes of the two Botryosphaeria species. Botryosphaeria kuwatsukai, which infects only apple and pear, apparently lost a set of SMs genes, CAZYs and PCWDEs, possibly as a result of host specialization. Botryosphaeria kuwatsukai contained significantly more transposable elements and higher value of repeat induced point (RIP) index than B. dothidea. Our results will be instrumental in understanding how both phytopathogens interact with their plant hosts and in designing efficient strategies for disease control and molecular breeding to help ensure global apple production and food security.
