EVALUATION OF THE INHERITANCE OF ANTHRACNOSE RESISTANCE GENE CO-1 IN COMMON BEAN

Abstract

ommon bean (Phaseolus vulgaris L.) is being cultivated worldwide due to its high dietary demand. Bean anthracnose, caused by Colletotrichum lindemuthianum, is the most destructive fungal disease of common bean which can lead up to 100% yield loss under severe conditions. The introduction of resistant varieties is considered the most effective method over other measures for controlling the disease. Top Crop is a high-yielding variety of bush bean commonly grown by Sri Lankan farmers yet severely susceptible to bean anthracnose, while PC-50 is an imported bush bean variety that is highly resistant to bean anthracnose. An investigation was conducted to assess the heritability of resistance to bean anthracnose in bush bean cultivar PC-50 in the genetic background of bush bean variety Top Crop. The present study evaluated the effectiveness of the Co-1 gene in imparting resistance across generations in the cross between PC-50 and Top Crop. The F2 generation of Top Crop and PC-50 seedlings was inoculated with spore suspension of C. lindemuthianum by artificial and natural field inoculation. Symptoms in bean leaves and pods were evaluated on a nine-point disease severity scale. The results were analysed by the Chi-square test and revealed no significant difference between the observed and expected ratios (p>0.05), confirming that inheritance of the gene happened according to Mendel's first law. In conclusion, the inheritance of the Co-1 gene occurs independently in bean cultivar PC-50 in the genetic background of the variety Top Crop and can be utilized effectively in the development of anthracnose-resistant bush bean varieties.