一种新的棉花黄萎病快速接种技术及其在病原菌致病力和寄主抗病性鉴定上的应用

A new inoculation method for Verticillium wilt on cotton and its application in evaluating pathogenesis and host resistance M

棉花品种抗黄萎病鉴定一般在田间病圃中进行,其结果受病圃中病原菌分布均匀程度、气象等因素影响极大,往往导致鉴定结果不准确。为了使鉴定方法简单、科学、可靠,我们在温室条件下比较了3种苗期接种棉花黄萎病的方法,即切根蘸孢子法(接种浓度为106分生孢子/mL);菌培养物土壤接种法(0.5％、1％、2％,w/w);微菌核土壤接种法(103个微菌核/g土)。结果表明,切根蘸孢子法导致棉苗发病均匀、严重、迅速,播种35-45 d后即可得到均匀一致的发病结果。而其它2种接种方法在播种75 d后才得到相对稳定的发病结果。同时,研究还表明接种浓度为104分生孢子/mL所导致的黄萎病显著比105或106的轻。利用切根蘸孢子法在室内鉴定12个棉花品种或品系的抗黄萎病能力,证明该方法是抗黄萎病快速鉴定的有效方法。此外,该鉴定方法还可快速鉴定黄萎病菌不同菌株的致病性,并可应用于作物对其它土传病害的抗病性鉴定上。

Three inoculation methods:cotton root injured and dipped in a spore suspension (106 conidia/ mL) , soil infested with Verticillium dahliae grown on wheat bran and corn meal (1:1 w/w) in the ratio of 0. 5%, 1% and 2% (w/w), and soil infested with microsclerotia (103 microsclerotia/g soil), were compared in the greenhouse for their effectiveness in infection and development of Verticillium wilt of cotton. Results showed that, among the three inoculation methods, the root dipping was the most effective method as judged from symptom development. The entire test for the root-dipping method required 35-45 days whereas the other two soil treatment methods required 75 days. For the root-dipping method, more severe disease was observed at the inoculum density of 105 or 106 conidia/mL than at 104 conidia/mL. The disease resistances of 12 cotton varieties or lines were assessed by the root-dipping method in the greenhouse. This study suggests that root inoculation of young cotton seedlings is a useful method for rapid screening of cotton cultivars/lines for resistance to Verticillium wilt. Meanwhile, this method is also useful in testing differences in pathogenicity of strains of V. dahliae from various hosts.