Wang Mingshuang, Liu Bei, Ruan Ruoxin, Zeng Yibing, Luo Jinshui, Li Hongye
College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou, China.
Key Laboratory of Molecular Biology of Crop Pathogens and Insects, Ministry of Agriculture, Institute of Biotechnology, Zhejiang University, Hangzhou, China.
Front Microbiol. 2020 Jan 10;10:2979. doi: 10.3389/fmicb.2019.02979. eCollection 2019.
, , and are three very important species associated with citrus. is an endophyte fungus of citrus while can cause black spot of citrus (e.g., oranges and mandarins). was identified recently which is the causal agent of the pomelo tan spot. Here, we present the ∼34 Mb genome of . The genome is organized in 92 contigs, encompassing 9202 predicted genes. Comparative genomic analyses with two other species ( and ) associated with citrus was conducted to understand their evolutionary conservation and diversification. Pair-wise genome alignments revealed that these species are highly syntenic. All species encode similar numbers of CAZymes and secreted proteins. However, the molecular functions of the secretome showed that each species contains some enzymes with distinct activities. The three species investigated shared a core set of 7261 protein families. had the largest set of orphan genes (1991), in complete contrast to that of (364) and (262). Most of the orphan genes are functionally unknown, but they contain a certain number of species-specific secreted proteins. A total of 23 secondary metabolites biosynthesis clusters were identified in the three species, 21 of them being highly conserved among these species while the remaining two showed whole cluster gain and loss polymorphisms or gene content polymorphisms. Taken together, our study reveals insights into the genetic mechanisms of host adaptation of three species of associated with citrus and paves the way to identify effectors that function in infection of citrus plants.
X. citri, X. aurantifolii 和 X. fuscans 是与柑橘相关的三个非常重要的黄单胞菌属物种。X. citri 是柑橘的一种内生真菌，而 X. aurantifolii 可导致柑橘（如橙子和橘子）出现黑斑病。最近鉴定出了 X. fuscans，它是柚褐点病的病原体。在此，我们展示了 X. fuscans 约34 Mb 的基因组。该基因组由92个重叠群组成，包含9202个预测基因。对与柑橘相关的另外两个黄单胞菌属物种（X. citri 和 X. aurantifolii）进行了比较基因组分析，以了解它们的进化保守性和多样性。成对基因组比对显示这些物种具有高度的共线性。所有物种编码的碳水化合物活性酶（CAZyme）和分泌蛋白数量相似。然而，分泌蛋白质组的分子功能表明，每个物种都含有一些具有不同活性的酶。所研究的这三个黄单胞菌属物种共有一组7261个蛋白质家族的核心集合。X. fuscans 拥有最大数量的孤儿基因（1991个），这与 X. citri（364个）和 X. aurantifolii（262个）形成了鲜明对比。大多数孤儿基因的功能未知，但它们包含一定数量的物种特异性分泌蛋白。在这三个黄单胞菌属物种中总共鉴定出23个次生代谢物生物合成簇，其中21个在这些物种中高度保守，而其余两个则表现出整个簇的获得和丢失多态性或基因含量多态性。综上所述，我们的研究揭示了与柑橘相关的三种黄单胞菌属物种宿主适应性的遗传机制，并为鉴定在柑橘植物感染中起作用的效应子铺平了道路。
