ABSTRACT

The process of protein translocation into the endoplasmic reticulum (ER) is the initial and decisive step in the biosynthesis of all secretory proteins and many soluble organelle proteins. In this process, the Sec61 complex is the protein-conducting channel for transport. In this study, we identified and characterized the β subunit of the Sec61 complex in Magnaporthe oryzae (MoSec61β). Compared with the wild-type strain Guy11, the ΔMosec61β mutant exhibited highly branched mycelial morphology, reduced conidiation, high sensitivity to cell wall integrity stress, severely reduced virulence to rice and barley, and restricted biotrophic invasion. The turgor pressure of ΔMosec61β was notably reduced, which affected the function of appressoria. Moreover, ΔMosec61β was also sensitive to oxidative stress and exhibited a reduced ability to overcome plant immunity. Further examination demonstrated that MoSec61β affected the normal secretion of the apoplastic effectors Bas4 and Slp1. In addition, ΔMosec61β upregulated the level of ER-phagy. In conclusion, our results demonstrate the importance of the roles played by MoSec61β in the fungal development and pathogenesis of M. oryzae.

摘要

蛋白质易位到内质网 (ER) 的过程是所有分泌蛋白质和许多可溶性细胞器蛋白质生物合成的初始和决定性步骤。在这个过程中，Sec61 复合物是蛋白质运输的传导通道。在这项研究中，我们鉴定并表征了稻瘟病菌中Sec61 复合物的 β 亚基（MoSec61β）。与野生型菌株 Guy11 相比，Δ Mosec61β突变体表现出高度分支的菌丝形态，减少的分生孢子，对细胞壁完整性应激的高度敏感性，对水稻和大麦的毒力严重降低，生物营养入侵受到限制。Δ Mosec61β的膨压显着降低，影响了附着物的功能。此外，ΔMosec61β也对氧化应激敏感，并表现出克服植物免疫的能力降低。进一步检查表明 MoSec61β 影响质外体效应子 Bas4 和 Slp1 的正常分泌。此外，Δ Mosec61β上调内质网自噬水平。总之，我们的结果证明了 MoSec61β 在M. oryzae的真菌发育和发病机制中所起的重要作用。