低温和常温下萌发的青霉菌孢子比较转录组研究

Comparative transcriptome study on Penicillium expansum spores during germination at low and normal temperatures

扩展青霉菌是一种自然界中分布广泛的常见植物病原真菌,其侵染采后果实,造成腐烂和霉变.为了发掘低温和常温下孢子萌发过程中差异的分子机制和参与孢子萌发的重要基因,分别对4℃和25℃下培养的扩展青霉菌孢子进行转录组测序;利用比较转录组分析方法进行基因表达数据的挖掘和比较分析.形态学观察表明,25℃培养8 h后,孢子呈现凸起,开始萌发;12 h后,大部分孢子萌发形成细长菌丝,完成萌发过程.而4℃培养12 h后,孢子的萌发仍然被抑制.对4℃和25℃下分别培养8、12 h的孢子取样,进行转录组测序.差异表达基因的分析表明:4℃和25℃下,不同的细胞生长和分裂相关基因在孢子萌发过程中差异表达;同时挖掘得到608个温度调控孢子萌发的核心基因.此外,萌发过程中,与扩展青霉菌毒力相关的部分过氧化物酶编码基因、效应因子基因和棒曲霉素合成途径基因的表达水平明显响应了温度的变化;参与了不同温度下孢子萌发的调控.效应因子基因PeHsp70_1被鉴定为是一个参与低温调控孢子萌发且涉及多个通路的重要基因;其在4℃下培养的孢子中明显被下调表达,与其他效应因子的蛋白互作网络分析表明其处于网络的核心中央节点.本研究结果可为扩展青霉菌的防治研究提供优良的候选基因.(图9表3参39)

Penicillium expansum is a plant pathogen that is widely distributed in nature and can infect postharvest fruits,resulting in decay and mildew infection.In this study,we identified important germination-related genes and explored differential molecular mechanisms of spore germination at normal and low temperatures by performing RNA sequencing(RNA-seq)experiments on P.expansum spores incubated at 25 and 4℃,respectively.Mining and comparative analyses of the gene expression data were performed using comparative transcriptome data analysis methods.After 8 h of incubation at 25℃,the spores exhibited protuberances,and germination had started.After 12 h of incubation at 25℃,most of the spores had germinated to form mycelia.In contrast,after 12 h of incubation at 4℃,no signs of spore germination were visible.Spores incubated for 8 and 12 h at 4 and 25℃,respectively,were collected and used for RNA-seq.Data analyses of the differentially expressed genes revealed that different cell growth-and division-related genes were involved in spore germination at low and normal temperatures.In total,608 core genes involved in the temperature-dependent regulation of spore germination were identified.Additionally,during germination,the expression levels of some virulence-related genes,including peroxidase-encoding genes,effector genes,and genes involved in patulin biosynthesis exhibited clear temperature-dependent regulation patterns.For example,PeHsp70-1 was demonstrated to be involved in spore germination regulation at low temperatures as well as being an important effector gene involved in multiple pathways.PeHsp70-1 showed significantly decreased expression in spores incubated at 4℃.The protein interaction network of PeHsp70-1 and other effectors indicated that PeHsp70-1 was located in the central core node of the network.Our results are likely to provide potential gene candidates for control studies of P.expansum pathogenesis.