Pathogen identification of pepper anthracnose and physiological changes of pepper under anthracnose stress
[Objective]In order to develop effective preventative measure and explore the physiological mechanism of disease-resistance,the study aimed to identify the pathogens of pepper anthracnose in Chengdu area and analyze the effect of anthracnose stress on critical physiolog-ical indexes in pepper leaves.[Method]The pathogen fungal strains were isolated and purified from symptomatic fruits and identified by using morphological observation and PCR amplification based on ITS gene sequence analysis.Simultaneously,the MDA content and the activities of various antioxidant enzymes in pepper leaves infected by the pathogens were measured.[Result]11 strains were isolated via tissue isolation from the diseased fruits of major pepper-planting regions in Chengdu.Colony morphology,sequence alignment and phylogenetic tree construc-tion confirmed that 9 strains were Colletotrichum scovillei and 2 strains were C.fructicola and the lesion diameter,incidence and disease index caused by C.scovillei were higher than those caused by C.fructicola.Meanwhile,the changes of physiological characteristics in pepper leaves under the C.Scovillei and C.flucticola infection were studied in the work.The results showed that a series of antioxidases were activated by anthracnose stress,peroxidase(POD),superoxide dismutase(SOD)and catalase(CAT)activities increased post-infection,peaking on 4 days before continuously declining.The content of MDA was decreased at the initial stage(in the 4 days)due to the activation of antioxidas-es.With the continuous infection,the activity of antioxidases decreased,resulting in the increase of MDA content.[Conclusion]The main pathogens causing pepper anthracnose in Chengdu area are C.scovillei and C.fructicola and the pathogenicity of C.scovillei is stronger than that of C.fructicola.Physiological analysis shows that MDA,SOD,POD and CAT in pepper leaves under anthracnose stress are identified as key important indicators for evaluating pepper disease-resistance.The study provides a theoretical basis for disease control,resistance breeding and elucidation of mechanism.
万方数据
维普
