School of Forestry, Northeast Forestry University, 26 Hexing Road, Harbin, 150040, China.
College of Forestry, Shenyang Agricultural University, Shenyang, 110866, China; Key Laboratory of Biogeography and Bioresource in Arid Land, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Urumqi, 830011, China.
Microbiol Res. 2021 Jul;248:126767. doi: 10.1016/j.micres.2021.126767. Epub 2021 Apr 7.
Xylanase secreted by Trichoderma asperellum ACCC30536 can stimulate the systemic resistance of host plants against pathogenic fungi. Following T. asperellum conidia co-culture with Populus davidiana × P. alba var. pyramidalis Louche (PdPap) seedlings, the expression of xylanases TasXyn29.4 and TasXyn24.2 in T. asperellum were upregulated, peaking at 12 h, by 106 (2) and 10.1 (2)-fold compared with the control, respectively. However, the expression of TasXyn24.4 and TasXyn24.0 was not detected. When recombinant xylanases rTasXyn29.4 and rTasXyn24.2 were heterologously expressed in Pichia pastoris GS115, their activities reached 18.9 IU/mL and 20.4 IU/mL, respectively. In PdPap seedlings induced by rTasXyn29.4 and rTasXyn24.2, the auxin and jasmonic acid signaling pathways were activated to promote growth and enhance resistance against pathogens. PdPap seedlings treated with both xylanases showed increased methyl jasmonate contents at 12 hpi, reaching 122 % (127 μg/g) compared with the control. However, neither of the xylanases could induce the salicylic acid signaling pathway in PdPap seedlings. Meanwhile, both xylanases could enhance the antioxidant ability of PdPap seedlings by improving their catalase activity. Both xylanases significantly induced systemic resistance of PdPap seedlings against Alternaria alternata, Rhizoctonia solani, and Fusarium oxysporum. However, the xylanases could only be sensed by the roots of the PdPap seedlings, not the leaves. In summary, rTasXyn29.4 and rTasXyn24.2 from T. asperellum ACCC30536 promoted growth and induced systemic resistance of PdPap seedlings, which endowed the PdPap seedlings broad-spectrum resistance to phytopathogens.
木聚糖酶由里氏木霉 ACCC30536 分泌，可刺激宿主植物对病原真菌的系统抗性。在里氏木霉孢子与银腺杨×银白杨杂种（PdPap）幼苗共培养后，里氏木霉中的木聚糖酶 TasXyn29.4 和 TasXyn24.2 的表达分别上调了 106（2）和 10.1（2）倍，峰值出现在 12 小时，而 TasXyn24.4 和 TasXyn24.0 的表达则未检测到。当重组木聚糖酶 rTasXyn29.4 和 rTasXyn24.2 在毕赤酵母 GS115 中异源表达时，其活性分别达到 18.9 IU/mL 和 20.4 IU/mL。在 rTasXyn29.4 和 rTasXyn24.2 诱导的 PdPap 幼苗中，生长素和茉莉酸信号通路被激活，促进了生长并增强了对病原体的抗性。PdPap 幼苗处理这两种木聚糖酶后，12 hpi 时茉莉酸甲酯含量增加，达到对照的 122%（127μg/g）。然而，这两种木聚糖酶都不能诱导 PdPap 幼苗中水杨酸信号通路的激活。同时，这两种木聚糖酶都可以通过提高过氧化氢酶的活性来增强 PdPap 幼苗的抗氧化能力。两种木聚糖酶都能显著诱导 PdPap 幼苗对Alternaria alternata、Rhizoctonia solani 和 Fusarium oxysporum 的系统抗性。然而，木聚糖酶只能被 PdPap 幼苗的根部感知，而不能被叶片感知。总之，来自里氏木霉 ACCC30536 的 rTasXyn29.4 和 rTasXyn24.2 促进了 PdPap 幼苗的生长并诱导了其系统抗性，使 PdPap 幼苗对植物病原体具有广谱抗性。
