PDF(Pubmed)
Abstract：
Trichoderma spp. are widely used biocontrol agents which are antagonistic to a variety of plant pathogens. Chlamydospores are a type of propagules produced by many fungi that have thick walls and are highly resistant to adverse environmental conditions. Chlamydospore preparations of Trichoderma spp. can withstand various storage conditions, have a longer shelf life than conidial preparations and have better application potential. However, large-scale production of chlamydospores has proven difficult. To understand the molecular mechanisms governing chlamydospore formation (CF) in Trichoderma fungi, we performed a comprehensive analysis of transcriptome dynamics during CF across 8 different developmental time points, which were divided into 4 stages according to PCA analysis: the mycelium growth stage (S1), early and middle stage of CF (S2), flourishing stage of CF (S3), and late stage of CF and mycelia initial autolysis (S4). 2864, 3206, and 3630 DEGs were screened from S2 vs S1, S3 vs S2, and S4 vs S3, respectively. We then identified the pathways and genes that play important roles in each stage of CF by GO, KEGG, STC and WGCNA analysis. The results showed that DEGs in the S2 vs S1 were mainly enriched in organonitrogen compound metabolism, those in S3 vs S2 were mainly involved in secondary metabolite, cell cycle, and N-glycan biosynthesis, and DEGs in S4 vs S3 were mainly involved in lipid, glycogen, and chitin metabolic processes. We speculated that mycelial assimilation and absorption of exogenous nitrogen in the early growth stage (S1), resulted in subsequent nitrogen deficiency (S2). At the same time, secondary metabolites and active oxygen free radicals released during mycelial growth produced an adverse growth environment. The resulting nitrogen-deficient and toxin enriched medium may stimulate cell differentiation by initiating cell cycle regulation to induce morphological transformation of mycelia into chlamydospores. High expression of genes relating to glycogen, lipid, mannan, and chitin synthetic metabolic pathways during the flourishing (S3) and late stages (S4) of CF may be conducive to energy storage and cell wall construction in chlamydospores. For further verifying the functions of the amino sugar and nucleotide sugar metabolism (tre00520) pathway in the CF of T. virens GV29-8 strain, the chitin synthase gene (TRIVIDRAFT_90152), one key gene of the pathway, was deleted and resulted in the dysplasia of mycelia and an incapability to form normal chlamydospores, which illustrated the pathway affecting the CF of T. virens GV29-8 strain. Our results provide a new perspective for understanding the genetics of biochemical pathways involved in CF of Trichoderma spp.
摘要：
木霉属。是广泛使用的生物防治剂，对多种植物病原体具有拮抗作用。衣原体孢子是由许多真菌产生的一种繁殖体,其具有厚壁并且对不利的环境条件具有高度抗性。木霉属衣原体孢子制剂。可以承受各种储存条件，具有比分生孢子制剂更长的保质期，具有更好的应用潜力。然而,大规模生产的衣原体孢子已被证明是困难的。为了了解木霉属真菌衣原体孢子形成（CF）的分子机制，我们对8个不同发育时间点的CF过程中的转录组动态进行了全面分析，根据PCA分析将其分为4个阶段：菌丝生长阶段（S1），CF（S2）的早期和中期，CF（S3）的蓬勃发展阶段，以及CF和菌丝体初始自溶的晚期（S4）。分别从S2vsS1、S3vsS2和S4vsS3筛选2864、3206和3630DEGs。然后，我们通过GO鉴定了在CF的每个阶段中起重要作用的通路和基因，KEGG,STC和WGCNA分析。结果表明，S2和S1中的DEGs主要富集在有机氮化合物代谢中，S3和S2中的那些主要涉及次级代谢产物，细胞周期,和N-聚糖生物合成，S4和S3中的DEGs主要涉及脂质，糖原，和几丁质代谢过程。我们推测菌丝同化和吸收外源氮在生长早期(S1),导致随后的氮缺乏（S2）。同时,菌丝生长过程中释放的次生代谢产物和活性氧自由基产生了不利的生长环境。所得的氮缺乏和毒素富集的培养基可以通过启动细胞周期调节以诱导菌丝体向衣原体孢子的形态转化来刺激细胞分化。与糖原相关的基因的高表达，脂质，甘露聚糖,在CF的繁盛（S3）和后期（S4）过程中，几丁质合成代谢途径可能有助于衣原体孢子中的能量存储和细胞壁构建。为了进一步验证T.virensGV29-8菌株CF中氨基糖和核苷酸糖代谢（tre00520）途径的功能，几丁质合成酶基因(TRIVIDRAFT_90152)，该途径的一个关键基因，被删除，导致菌丝体发育不良和无法形成正常的衣原体孢子，这说明了影响T.virensGV29-8菌株CF的途径。我们的研究结果为理解木霉属CF涉及的生化途径的遗传学提供了新的视角。
