The pine wilt disease (PWD), for which no efective treatment is available at the moment, is a constant threat to Pinus spp. plantations worldwide, being responsible for signifcant economic and environmental losses every year. Prevention is undoubtedly the best approach to reduce PWD incidence and diferent strategies have been suggested to avoid or treat the disease by: targeting the nematode itself, the vector, the host, or a combination of all three. Several synthetic compounds have already been developed to control the PWD, but many of them are toxic to the environment, labour intensive to apply, and expensive. Previous studies suggested that chitosan can be used to enhance plant defence against bacteria, fungi and nematodes.Chitosan acts as a plant growth promoter, stimulating responses associated with both primary and secondary metabolism, including: carbon and nitrogen metabolism, primary photochemistry and photosynthesis, the tricarboxylic acid cycle, and terpenoid and phenolic compounds biosynthesis.
To understand the infuence of chitosan in Pinus pinaster tolerance against PWN, a low-molecularweight (327kDa) 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-efect of chitosan. Combined, we conclude that chitosan induces pine defences against PWD via modulation of metabolic and transcriptomic mechanisms related with plant antioxidant system.
Figure 1. Nematode population in plant tissues. Nematode density in P. pinaster stem tissues 1, 7, 14, 21 and 28 days post-inoculation (dpi). Plants were inoculated with the pinewood nematode (PWN) B. xylophilus 14 days following the application of 0.5% acetic acid (without chitosan, non-elicited controls) or a chitosan solution to plants’ substrate. Data represents the diference between the averages of PWN-inoculated and waterinoculated plants±SE, and diferent letters indicate statistically diferent means at P < 0.05.
Reference:Chitosan increases Pinus pinaster tolerance to the pinewood nematode (Bursaphelenchus xylophilus) by promoting plant antioxidative metabolism
BZ Oligo mainly offer marine oligosaccharide standards and ingredients, containing alginate oligosaccharide, chitosan oligosaccharide, agar oligosaccharide and carrageenan oligosaccharide, which give business opportunities using these untapped oligosaccharides for biological applications targeting lab research, pharmacy, dietary supplement, sustainable agriculture and animal health.
Factory