西瓜枯萎病生防链霉菌的筛选及其防治机理研究

Screening of Biocontrol Streptomyces against Fusarium Wilt of Watermelon and Its Study on Control Mechanism

为了安全高效地防治西瓜枯萎病,本研究用平板对峙法从本实验室保存的7株链霉菌中筛选出拮抗西瓜枯萎病效果良好的链霉菌,并结合链霉菌发酵滤液和菌体粗提物对西瓜枯萎病菌生长的抑制效果进行复筛。结果表明:7株链霉菌中,YC2-17(Streptomyces tunisialbus)和YC5-15(S.eurocidicus)对西瓜枯萎病菌抑制效果最好,抑菌率可达56.21%和54.72%。西瓜幼苗的促生试验结果表明,这两株链霉菌对西瓜幼苗的生长都具有显著的促进作用,其中链霉菌YC2-17的促生效果更强,YC2-17处理后西瓜幼苗的株高、根长、鲜重和干重分别增加了52.54%、27.65%、109.57%和100.00%。盆栽防病试验结果表明,YC2-17和YC5-15发酵液对西瓜枯萎病的防效可达56.82%和50.45%。YC2-17发酵滤液的乙酸乙酯相粗提物处理可以抑制西瓜枯萎病菌的孢子萌发,减少其产孢量,改变孢子和菌丝体的形态,处理后菌丝和孢子外部形态异常、躯干干扁,内容物外渗。

In order to prevent and control watermelon Fusarium wilt safely and efficiently,in this study,seven Streptomyces with good antagonistic effect against Fusarium oxysporum f.sp.niveum(FON)were selected using plate confrontation method.The inhibitory effect of Streptomyces fermentation filtrate and bacterial crude extract on the growth of FON was investigated.Among these seven Streptomyces,Streptomyces tunisialbus YC2-17 and S.eurocidicus YC5-15 showed strong inhibitory effect on FON,with inhibitory rates of 56.21%and 54.72%.In addition,the plant growth-promoting experiments on watermelon seedlings were carried out.The results showed that the two Streptomyces had significant promoting effects on the growth of watermelon seedlings,and YC2-17 had better promoting effect.After YC2-17 treatment,the plant height,root length,fresh weight and dry weight of watermelon seedlings increased by 52.54%,27.65%,109.57%and 100.00%.The result of the potted plant experiments demonstrated that the control effects of YC2-17 and YC5-15 fermentation solution on watermelon Fusarium wilt were 56.82%and 50.45%,respectively.The treatment of ethyl acetate phase crude extract of YC2-17 fermentation filtrate could inhibit the formation and germination of FON spores,change the morphology of spores and mycelium.After treatment,the external morphology of hyphae and spores was abnormal,the trunk were flat,and the contents were exuded.