Affiliation:
1. State Key Laboratory of Agricultural Microbiology and Key Laboratory of Plant Pathology of Hubei Province Huazhong Agricultural University Wuhan China
2. Institute of Cash Crops, Xinjiang Academy of Agricultural Sciences Urumqi China
Abstract
AbstractIn order to understand the epidemiological features of rapeseed blackleg in northern China, a 2‐year survey of blackleg on wild mustard (Sinapis arvensis) and rapeseed (Brassica napus) was done in Zhaosu County of Xinjiang Uyghur Autonomous Region of China. Blackleg frequently occurs on both plants in this region, with mean values of disease incidence reaching up to 28% on wild mustard and 14% on rapeseed. A total of 556 pycnidia‐forming fungal isolates were obtained from wild mustard (69) and rapeseed (487). Morphological and molecular identification indicated that all of the 69 isolates from wild mustard and the majority of the isolates from rapeseed (477/487, 97.9%) belonged to Leptosphaeria biglobosa ‘canadensis’ (Lb‐c); the remaining 10 isolates from rapeseed (10/487, 2.1%) belonged to L. biglobosa ‘brassicae’ (Lb‐b). Among 239 isolates of Lb‐c (62 from wild mustard and 177 from rapeseed), two mating‐type idiomorphs (MAT1‐1 and MAT1‐2) were detected. Chi‐square test showed that the ratio of MAT1‐1 to MAT1‐2 of isolates was 1:1, implying that the individuals of Lb‐c can frequently conduct sexual reproduction to produce ascospores as the primary airborne infection source. The virulence of 10 Lb‐c isolates from wild mustard and rapeseed and five Lb‐b isolates from rapeseed was determined on both plants. The results showed that the Lb‐c isolates from wild mustard were as virulent as isolates of Lb‐c and Lb‐b from rapeseed. Thus, Lb‐c can act as inoculum of rapeseed blackleg, and eliminating plants of wild mustard may improve efficacy of crop rotation in suppression of rapeseed blackleg.