Marine Agriculture Research Center, Tobacco Research Institute of Chinese Academy of Agricultural Sciences, Qingdao, 266101, China.
Yunnan Kunming Tobacco Co., Ltd, Kunming, 650400, China.
Plant Physiol Biochem. 2024 Oct;215:108986. doi: 10.1016/j.plaphy.2024.108986. Epub 2024 Aug 3.
Arbuscular mycorrhizal fungi (AMF) and Chitooligosaccharide (COS) can increase the resistance of plants to disease. COS can also promote the symbiosis between AMF and plants. However, the effects of AMF & COS combined application on the rhizosphere soil microbial community of tobacco and the improvement of tobacco's resistance to black shank disease are poorly understood.·We treated tobacco with AMF, COS, and combined application of AMF & COS (AC), respectively. Then studied the incidence, physio-biochemical changes, root exudates, and soil microbial diversity of tobacco seedling that was inoculated with Phytophthora nicotianae. The antioxidant enzyme activity and root vigor of tobacco showed a regular of AC > AMF > COS > CK, while the severity of tobacco disease showed the opposite regular. AMF and COS enhance the resistance to black shank disease by enhancing root vigor, and antioxidant capacity, and inducing changes in the rhizosphere microecology of tobacco. We have identified key root exudates and critical soil microorganisms that can inhibit the growth of P. nicotianae. The presence of caprylic acid in root exudates and Bacillus (WdhR-2) in rhizosphere soil microorganisms is the key factor that inhibits P. nicotianae growth. AC can significantly increase the content of caprylic acid in tobacco root exudates compared to AMF and COS. Both AMF and COS can significantly increase the abundance of Bacillus in tobacco rhizosphere soil, but the abundance of Bacillus in AC is significantly higher than that in AMF and COS. This indicates that the combined application of AMF and COS is more effective than their individual use. These findings suggest that exogenous stimuli can induce changes in plant root exudates, regulate plant rhizosphere microbial community, and then inhibit the growth of pathogens, thereby improving plant resistance to diseases.
丛枝菌根真菌（AMF）和壳寡糖（COS）可以提高植物的抗病性。COS 还可以促进 AMF 与植物的共生。然而，AMF 和 COS 联合应用对烟草根际土壤微生物群落的影响以及提高烟草对黑胫病的抗性尚不清楚。
我们分别用 AMF、COS 和 AMF 和 COS 联合处理（AC）处理烟草，然后研究了接种烟草疫霉后烟草幼苗的发病率、生理生化变化、根系分泌物和土壤微生物多样性。烟草的抗氧化酶活性和根活力表现出 AC>AMF>COS>CK 的规律，而烟草病害的严重程度则表现出相反的规律。AMF 和 COS 通过增强根活力和抗氧化能力，以及诱导烟草根际微生态变化来提高对黑胫病的抗性。我们已经确定了可以抑制 P. nicotianae 生长的关键根系分泌物和关键土壤微生物。根系分泌物中存在辛酸和根际土壤微生物中的芽孢杆菌（WdhR-2）是抑制 P. nicotianae 生长的关键因素。与 AMF 和 COS 相比，AC 可显著增加烟草根系分泌物中辛酸的含量。AMF 和 COS 均可显著增加烟草根际土壤中芽孢杆菌的丰度，但 AC 中芽孢杆菌的丰度明显高于 AMF 和 COS。这表明 AMF 和 COS 的联合应用比单独使用更有效。这些发现表明，外源刺激可以诱导植物根系分泌物发生变化，调节植物根际微生物群落，从而抑制病原菌的生长，提高植物的抗病性。
