Zhang Chengsheng, Feng Chao, Zheng Yanfen, Wang Jing, Wang Fenglong
Marine Agriculture Research Center, Tobacco Research Institute of Chinese Academy of Agricultural Sciences, Qingdao, China.
Qingdao Special Crops Research Center of Chinese Academy of Agricultural Sciences, Qingdao, China.
Front Plant Sci. 2020 Sep 10;11:559775. doi: 10.3389/fpls.2020.559775. eCollection 2020.
There is increasing evidence that root exudates play important roles in plant disease resistance. Black shank, caused by , is a destructive soil-borne disease in tobacco ( L.). The aim of the present study was to investigate the activity and composition of the root exudates from resistant and susceptible tobacco cultivars. The root exudates of the resistant cultivar Gexin 3 showed inhibitory activity against , while the exudates of susceptible cultivar Xiaohuangjin 1025 stimulated the colony growth but had no effect on spore germination. Metabolic profiling using liquid chromatography/electrospray ionization-quadrupole-time-of-flight mass spectrometry depicted differing metabolic patterns of root exudates between Gexin 3 and Xiaohuangjin 1025. The activity and composition of root exudates was altered by inoculation. Multivariate analysis showed that root exudates (including organic acids, alkaloids, fatty acids, and esters) were different between the two varieties. The defense substances in root exudates, such as tartaric acid, ferulic acid, and lauric acid, may represent a pre-infection prevention strategy for tobacco. Phenylpropanoids as well as inducers of salicylic acid, fatty acids, 6-hydroxyhexanoic acid, and hydrojasmonate may be involved in tobacco defense responses. Compared to the susceptible cultivar, the roots of the resistant cultivar exhibited high enzyme activities of phenylalanine ammonia-lyase, cinnamate-4-hydroxylase and 4-coumarate-CoA ligase, which may prompt the synthesis and secretion of phenylpropanoids. Our results indicated that the root exudates not only provide a pre-infection prevention strategy by exuding antimicrobial substances, but also increase tobacco disease resistance by eliciting plant defense responses. In addition, some defense compounds as well as compounds that play a role in inducing plant defense responses, showed potential for disease control application. This study provides an insight into possible disease resistance mechanisms of root exudates, and attempts the beneficial utilization of these secondary metabolites of plants.
越来越多的证据表明，根系分泌物在植物抗病性中发挥着重要作用。由[病原菌名称缺失]引起的黑胫病是烟草（Nicotiana tabacum L.）中一种具有毁灭性的土传病害。本研究的目的是调查抗性和感病烟草品种根系分泌物的活性和成分。抗性品种革新3的根系分泌物对[病原菌名称缺失]表现出抑制活性，而感病品种小黄金1025的分泌物则刺激菌落生长，但对孢子萌发没有影响。使用液相色谱/电喷雾电离-四极杆-飞行时间质谱进行的代谢谱分析描绘了革新3和小黄金1025之间根系分泌物不同的代谢模式。接种[病原菌名称缺失]改变了根系分泌物的活性和成分。多变量分析表明，两个品种之间的根系分泌物（包括有机酸、生物碱、脂肪酸和酯类）存在差异。根系分泌物中的防御物质，如酒石酸、阿魏酸和月桂酸，可能代表了烟草的一种感染前预防策略。苯丙烷类化合物以及水杨酸诱导剂、脂肪酸、6-羟基己酸和氢化茉莉酮酸酯可能参与烟草的防御反应。与感病品种相比，抗性品种的根系表现出较高的苯丙氨酸解氨酶、肉桂酸-4-羟化酶和4-香豆酸-CoA连接酶活性，这可能促进苯丙烷类化合物的合成和分泌。我们的结果表明，根系分泌物不仅通过分泌抗菌物质提供感染前预防策略，还通过引发植物防御反应提高烟草的抗病性。此外，一些防御化合物以及在诱导植物防御反应中起作用的化合物显示出疾病控制应用的潜力。本研究深入了解了根系分泌物可能的抗病机制，并尝试对这些植物次生代谢产物进行有益利用。
