ACTIVITY OF CHITOSAN WITH DIFFERENT MOLECULAR WEIGHTS ON ALTERNARIA SOLANI

ABSTRACT Chitosan has shown significant antifungal activity against several plant pathogens. The aim of this study was to evaluate the antifungal effect of chitosans on Alternaria solani, the causal agent of early blight in tomato. Three chitosans were used: a commercial one (Qcom), found in food supplement stores; one of low molecular weight (Qbpm; 50 - 190 KDa) and one of medium molecular weight (Qmpm; 190 - 310 KDa), the latter two obtained from Sigma Aldrich. The chitosan were deposited on slides, to assess the conidial germination and germ tube elongation, or incorporated into the BDA medium, to evaluate the mycelial growth of A. solani. The results showed an antifungal activity of these polysaccharides on A. solani, with inhibition of spore germination and mycelial growth of 85% and 50%, respectively, when used at concentrations of 0.125 mg/mL and 0.5 mg/mL. The molecular weight has not influenced the in vitro activity of chitosan.

摘要：壳聚糖(Chitosan)对多种植物病原菌具有显著抗真菌活性。本研究旨在评估壳聚糖对番茄早疫病病原菌茄链格孢(Alternaria solani)的抗真菌效果。本次实验采用三种壳聚糖：一款购自食品补充剂商店的市售产品(Qcom)；一款低分子量壳聚糖(Qbpm；分子量50~190 KDa)；一款中分子量壳聚糖(Qmpm；分子量190~310 KDa)，后两者均购自西格玛奥德里奇(Sigma Aldrich)。将壳聚糖涂布于载玻片上，以检测茄链格孢的分生孢子萌发与芽管伸长情况；或将其添加至BDA培养基中，以评估该病原菌的菌丝生长情况。实验结果表明，上述多糖类物质对茄链格孢具有抗真菌活性：当分别使用浓度为0.125 mg/mL与0.5 mg/mL的壳聚糖时，其对孢子萌发与菌丝生长的抑制率分别可达85%与50%。壳聚糖的分子量未对其体外抗真菌活性产生显著影响。