College of Agronomy and Biotechnology, Southwest University, Chongqing, China.
Engineering Research Center of South Upland Agriculture, Ministry of Education, Chongqing, China.
Mol Plant Pathol. 2021 Nov;22(11):1413-1426. doi: 10.1111/mpp.13127. Epub 2021 Aug 30.
Sclerotinia sclerotiorum infects host plant tissues by inducing necrosis to source nutrients needed for its establishment. Tissue necrosis results from an enhanced generation of reactive oxygen species (ROS) at the site of infection and apoptosis. Pathogens have evolved ROS scavenging mechanisms to withstand host-induced oxidative damage. However, the genes associated with ROS scavenging pathways are yet to be fully investigated in S. sclerotiorum. We selected the S. sclerotiorum Thioredoxin1 gene (SsTrx1) for our investigations as its expression is significantly induced during S. sclerotiorum infection. RNA interference-induced silencing of SsTrx1 in S. sclerotiorum affected the hyphal growth rate, mycelial morphology, and sclerotial development under in vitro conditions. These outcomes confirmed the involvement of SsTrx1 in promoting pathogenicity and oxidative stress tolerance of S. sclerotiorum. We next constructed an SsTrx1-based host-induced gene silencing (HIGS) vector and mobilized it into Arabidopsis thaliana (HIGS-A) and Nicotiana benthamiana (HIGS-N). The disease resistance analysis revealed significantly reduced pathogenicity and disease progression in the transformed genotypes as compared to the nontransformed and empty vector controls. The relative gene expression of SsTrx1 increased under oxidative stress. Taken together, our results show that normal expression of SsTrx1 is crucial for pathogenicity and oxidative stress tolerance of S. sclerotiorum.
核盘菌通过诱导宿主组织坏死来获取建立感染所需的营养物质，从而感染宿主植物组织。组织坏死是由于感染部位活性氧（ROS）的生成增强和细胞凋亡所致。病原体已经进化出 ROS 清除机制来抵御宿主诱导的氧化损伤。然而，核盘菌中与 ROS 清除途径相关的基因尚未得到充分研究。我们选择核盘菌硫氧还蛋白 1 基因（SsTrx1）进行研究，因为它在核盘菌感染过程中的表达显著诱导。RNA 干扰诱导 SsTrx1 在核盘菌中的沉默会影响菌丝生长速率、菌丝形态和体外条件下菌核的发育。这些结果证实了 SsTrx1 参与促进核盘菌的致病性和氧化应激耐受性。接下来，我们构建了基于 SsTrx1 的宿主诱导基因沉默（HIGS）载体，并将其转移到拟南芥（HIGS-A）和本氏烟（HIGS-N）中。与非转化和空载体对照相比，抗性分析显示转化基因型的致病性和疾病进展明显降低。在氧化胁迫下，SsTrx1 的相对基因表达增加。总之，我们的结果表明，SsTrx1 的正常表达对于核盘菌的致病性和氧化应激耐受性至关重要。
