Key Laboratory of Agricultural Environmental Microbiology, Ministry of Agriculture, Microbiology Department, College of Life Sciences, Nanjing Agricultural University, Nanjing 210095, Jiangsu, PR China.
Key Laboratory of Agricultural Environmental Microbiology, Ministry of Agriculture, Microbiology Department, College of Life Sciences, Nanjing Agricultural University, Nanjing 210095, Jiangsu, PR China.
Fungal Genet Biol. 2019 Feb;123:70-77. doi: 10.1016/j.fgb.2018.12.005. Epub 2018 Dec 14.
The fungal cell wall is very important for cell growth and survival during stress, and the target of rapamycin (TOR) pathway plays a major role in regulating cell growth in response to environmental cues. Ganoderma lucidum is an important edible and medicinal fungus, and the function of TOR in this organism remains unclear. As shown in the present study, the TOR pathway regulates cell wall integrity (CWI) in G. lucidum. Inhibition of TOR signaling by RNA interference (RNAi) or rapamycin treatment reduced the growth of G. lucidum mycelia, increased contents of the cell wall components chitin and β-1,3-glucan, and increased cell wall thickness. Furthermore, inhibition of TOR signaling enhanced the relative level of phosphorylated Slt2, a member of the MAPK cascade involved in CWI signaling. Moreover, when treated with rapamycin, significantly lower chitin and β-1,3-glucan contents were observed in Slt2-silenced strains than in WT strains, indicating that TOR regulates the synthesis of these cell wall components through the Slt2-MAPK pathway. These results indicate a potential relationship between TOR signaling and CWI signaling. Additionally, participation of Slt2-MAPK in TOR-mediated regulation of cell wall component production has not previously been reported in a microorganism.
真菌细胞壁对于细胞在压力下的生长和存活非常重要，而雷帕霉素（TOR）途径在调节细胞对环境信号的生长反应方面起着主要作用。灵芝是一种重要的食用和药用真菌，TOR 在该生物中的功能尚不清楚。如本研究所示，TOR 途径调节灵芝的细胞壁完整性（CWI）。通过 RNA 干扰（RNAi）或雷帕霉素处理抑制 TOR 信号会降低灵芝菌丝的生长速度，增加细胞壁成分几丁质和β-1,3-葡聚糖的含量，并增加细胞壁厚度。此外，抑制 TOR 信号会增强参与 CWI 信号的 MAPK 级联中的磷酸化 Slt2 的相对水平。此外，当用雷帕霉素处理时，沉默 Slt2 的菌株中几丁质和β-1,3-葡聚糖的含量明显低于 WT 菌株，表明 TOR 通过 Slt2-MAPK 途径调节这些细胞壁成分的合成。这些结果表明 TOR 信号与 CWI 信号之间存在潜在关系。此外，Slt2-MAPK 参与 TOR 介导的细胞壁成分产生的调节在以前的微生物中尚未报道过。
