四川玉米纹枯病菌致病性研究

从四川不同生态区采集玉米纹枯病穴Rhizoctoniaspp.雪症状的玉米叶鞘,经分离、鉴定,选取16个立枯丝核菌穴Rhizoctoniasolani雪AG1-IA的菌株和2个玉蜀黍丝核菌穴Rhizoctoniazeae雪菌株作为供试菌。在玉米成株期用PDA菌丝圆片定位接种于玉米叶鞘内侧,测定供试菌株在玉米植株上的垂直扩展情况穴病斑高度、日均扩展速度雪,区分病菌的致病性。还研究了AG1-IA不同致病性菌株体外产纤维素酶和果胶酶活性与致病性的关系。结果表明:分属于两个种的18个供试菌株均能侵染玉米,在潜育期上没有差异;病斑高度和病斑日均扩展速度能很好反映出菌株间致病性的差异,R.solaniAG1-IA菌株间的致病性有明显差异,R.zeae菌的致病性显著低于R.solaniAG1-IA菌株,体外产果胶酶和纤维素酶的活性大小与致病性有关联。

Studies on Pathogenicity of Rhizoctonia solani AG1-IA and R. zeae on Maize in Sichuan

Rhizoctonia-diseased specimens were collected from maize plants in different geographic regions in Sichuan.Sixteen R.solani AG1-IA isolates and two R.zeae isolates were obtained by tissue isolation and species identification,and were inoculated to determine the pathogenicity,using the leaf sheath inoculation method with 5mm discs of pure culture of each isolate in PDA.Lesion length and incubation period were measured.Analysis of data was performed by using DPS(Data Processing System) computer program.The results showed that the incubation period of all tested isolates was similar in 36 hr.All isolates were pathogenic to maize.The lesion height and spreading rate were significantly different among the isolates.There was considerable variation in pathogenicity among tested isolates on maize.The activities of pectinase(PG?PMG) and cellulase markedly increased with increasing pathogenicity of the isolate.It suggested that the activities of cell wall degrading enzymes(CWDE) were may related to pathogenicity.