稻曲病菌交配型基因MAT1-2-1和MAT1-2-8的特性分析

 有性生殖在真菌的生活史和进化过程中具有重要作用,而交配型基因是控制有性生殖的关键因子。前期研究发现稻曲病菌(Villosiclava virens)MAT1-2型菌株中包含MAT1-2-1和MAT1-2-8两个交配型基因,但是它们如何调控稻曲病菌有性生殖依然不清楚。本文研究了它们在不同侵染和生长发育时期的表达模式和编码的蛋白结构特性。研究表明MAT1-2-1在侵染不同阶段一直下调表达;而MAT1-2-8在侵染早期(5 dpi)上调表达,在侵染后期下调表达。与营养菌丝阶段比较,MAT1-2-1和MAT1-2-8在有性发育过程菌核形成、菌核萌发、子座原基形成和子座成熟4个阶段的表达量都是下降的,在菌核形成阶段表达量最低。生物信息学分析显示MAT1-2-1和MAT1-2-8具有磷酸化位点,为非分泌蛋白,无明显的跨膜结构域。蛋白同源比对分析表明MAT1-2-1与香柱菌(Epichloë typhina)的MAT1-2-1同源性最高,而MAT1-2-8与绿僵菌(Metarhizium)的MBR_08192蛋白同源性最高。进一步研究发现MAT1-2-1和MAT1-2-8能够互作,并分别主要定位在细胞核和细胞基质中。通过质谱技术鉴定到MAT1-2-1的一些候选互作蛋白,如假定Ran交换因子Prp20/Pim1(KDB12229.1)、假定rRNA处理蛋白Ebp2(KDB12923.1)及组蛋白H1(KDB12711.1)等。因此,以上结果为研究稻曲病菌交配型基因MAT1-2-1和MAT1-2-8调控有性生殖的生物学功能奠定了基础。

Characteristic analysis of mating-type genes MAT1-2-1 and MAT1-2-8 in Villosiclava virens

Sexual reproduction plays an important role in the life cycle and evolution of the fungi. Mating type genes are the master regulators of sexual reproduction. The MAT1-2 strain of Villosiclava virens contains two mating type genes, MAT1-2-1 and MAT1-2-8. However, how these two genes regulate sexual reproduction of V. virens remains largely unknown. In this study, we demonstrated the expression pattern of MAT1-2-1 and MAT1-2-8 at different stages of infection and development. We also analyzed the structural characteristics of these two proteins. The results showed that the expression level of MAT1-2-1 was reduced during infection stages. MAT1-2-8 was up-regulated at the early infection stage (5 dpi), and then decreased during late infection stage. Compared with the vegetative mycelium stage, the expression levels of both MAT1-2-1 and MAT1-2-8 were reduced in the four stages of sexual development sclerotia formation, sclerotia germination, stromata primordium formation and mature stromata, and the expression level was the lowest in the sclerotia formation stage. Bioinformatics analysis showed that MAT1-2-1 and MAT1-2-8 have phosphorylation sites, but no secretion peptides and no obvious transmembrane domains. Homologous alignment analysis showed that MAT1-2-1 shared high homology with its homolog in Epichloë typhina, and MAT1-2-8 shared high homology with its homolog in Metarhizium. Further study showed that MAT1-2-1 interacted with MAT1-2-8, and they were mainly localized in the nucleus and the cytoplasm, respectively. In addition, we identified several candidate proteins that might interact with MAT1-2-1 via mass spectrometry, including the putative Ran exchange factor Prp20/Pim1 (KDB12229.1), the putative rRNA processing protein (Ebp2) (KDB12923.1), and histone H1 (KDB12711.1). Collectively, these results provide fundamental understanding biological functions of the mating type genes MAT1-2-1 and MAT1-2-8 on sexual reproduction.