Wang Juan-Juan, Qiu Lei, Chu Zhen-Jian, Ying Sheng-Hua, Feng Ming-Guang
Institute of Microbiology, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang 310058, People's Republic of China.
Institute of Microbiology, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang 310058, People's Republic of China
Glycobiology. 2014 Jul;24(7):638-48. doi: 10.1093/glycob/cwu028. Epub 2014 Apr 11.
O-Mannosylation dependent on the protein O-mannosyltransferase (Pmt) family is an essential post-translational modification process in eukaryotes, but their connection to the biocontrol potential of a filamentous entomopathogen against arthropod pests is not understood. Here, we characterized the functions of three Pmt orthologues (Pmt1, Pmt2 and Pmt4) in the Pmt family of Beauveria bassiana and found that they were positive, but differential, regulators of the fungal growth, conidiation, multi-stress tolerance and virulence. Three Pmt2 knockdown mutants (ΔPmt2 was lethal), ΔPmt1 and ΔPmt4 grew 20-79% slower on nutrition-rich and limited media. Their conidial yields on a standard medium were reduced by 17-62%, accompanied with delayed germination. All the mutants became significantly less tolerant to most stresses of cell wall perturbation, high osmolarity, oxidation, wet heat and UV-B irradiation during colony growth and conidial germination and lost virulence by 53-62% via cuticle infection, although their virulence via hemocoel injection was not affected. Strikingly, these phenotypic defects were accompanied with remarkable cell wall damage, including thinner cell wall, lower conidial hydrophobicity and altered cell wall composition. All the changes were well restored to wild-type levels by targeted Pmt1 or Pmt4 complementation. Our results indicate for the first time that Pmt1, Pmt2 and Pmt4 are all required for the full biocontrol potential of B. bassiana despite differential contributions.
依赖于蛋白质O-甘露糖基转移酶（Pmt）家族的O-甘露糖基化是真核生物中一种重要的翻译后修饰过程，但其与丝状昆虫病原真菌对节肢动物害虫的生物防治潜力之间的联系尚不清楚。在此，我们对球孢白僵菌Pmt家族中的三个Pmt直系同源基因（Pmt1、Pmt2和Pmt4）的功能进行了表征，发现它们是真菌生长、产孢、多重胁迫耐受性和毒力的正向但有差异的调节因子。三个Pmt2基因敲除突变体（ΔPmt2致死）、ΔPmt1和ΔPmt4在营养丰富和有限的培养基上生长速度减慢了20%-79%。它们在标准培养基上的分生孢子产量降低了17%-62%，同时伴有萌发延迟。在菌落生长和分生孢子萌发过程中，所有突变体对细胞壁扰动、高渗透压、氧化、湿热和UV-B辐射等大多数胁迫的耐受性显著降低，通过体表感染其毒力丧失了53%-62%，尽管通过血腔注射的毒力不受影响。引人注目的是，这些表型缺陷伴随着明显的细胞壁损伤，包括细胞壁变薄、分生孢子疏水性降低和细胞壁组成改变。通过靶向Pmt1或Pmt4互补，所有这些变化都能很好地恢复到野生型水平。我们的结果首次表明，尽管贡献不同，但Pmt1、Pmt2和Pmt4对于球孢白僵菌的完全生物防治潜力都是必需的。
