Universidade Católica Portuguesa, CBQF - Centro de Biotecnologia e Química Fina - Laboratório Associado, Escola Superior de Biotecnologia, Rua de Diogo Botelho 1327, 4169-005, Porto, Portugal.
Misión Biológica de Galicia (MBG-CSIC), Carballeira 8, Salcedo, 36143, Pontevedra, Spain.
Sci Rep. 2021 Feb 12;11(1):3781. doi: 10.1038/s41598-021-83445-0.
The pine wilt disease (PWD), for which no effective treatment is available at the moment, is a constant threat to Pinus spp. plantations worldwide, being responsible for significant economic and environmental losses every year. It has been demonstrated that elicitation with chitosan increases plant tolerance to the pinewood nematode (PWN) Bursaphelenchus xylophilus, the causal agent of the PWD, but the biochemical and genetic aspects underlying this response have not been explored. To understand the influence of chitosan in Pinus pinaster tolerance against PWN, a low-molecular-weight (327 kDa) chitosan was applied to mock- and PWN-inoculated plants. Nematode population, malondialdehyde (MDA), catalase, carotenoids, anthocyanins, phenolic compounds, lignin and gene expression related to oxidative stress (thioredoxin 1, TRX) and plant defence (defensin, DEF, and a-farnesene synthase, AFS), were analysed at 1, 7, 14, 21 and 28 days post-inoculation (dpi). At 28 dpi, PWN-infected plants elicited with chitosan showed a sixfold lower nematode population when compared to non-elicited plants. Higher levels of MDA, catalase, carotenoids, anthocyanins, phenolic compounds, and lignin were detected in chitosan-elicited plants following infection. The expression levels of DEF gene were higher in elicited plants, while TRX and AFS expression was lower, possibly due to the disease containment-effect of chitosan. Combined, we conclude that chitosan induces pine defences against PWD via modulation of metabolic and transcriptomic mechanisms related with plant antioxidant system.
松材线虫病（PWD）目前尚无有效的治疗方法，是全球松属植物种植的一个持续威胁，每年都会造成重大的经济和环境损失。已证明壳聚糖的激发可以提高植物对松材线虫（PWN）的耐受性，松材线虫是 PWD 的致病因子，但这种反应的生化和遗传方面尚未得到探索。为了了解壳聚糖对欧洲赤松（Pinus pinaster）对 PWN 耐受性的影响，将低分子量（327 kDa）壳聚糖应用于模拟和 PWN 接种的植物。在接种后 1、7、14、21 和 28 天，分析了线虫种群、丙二醛（MDA）、过氧化氢酶、类胡萝卜素、花青素、酚类化合物、木质素以及与氧化应激（硫氧还蛋白 1，TRX）和植物防御（防御素，DEF 和 a-法呢烯合酶，AFS）相关的基因表达。在 28 dpi，与未激发的植物相比，用壳聚糖激发的感染 PWN 的植物中的线虫种群低了六倍。在感染后，壳聚糖激发的植物中检测到更高水平的 MDA、过氧化氢酶、类胡萝卜素、花青素、酚类化合物和木质素。在激发的植物中 DEF 基因的表达水平更高，而 TRX 和 AFS 的表达水平更低，这可能是由于壳聚糖对疾病的遏制作用。综上所述，壳聚糖通过调节与植物抗氧化系统相关的代谢和转录组机制来诱导松树对 PWD 的防御。
