Introgression of anthracnose resistance Co-4 gene in elite French bean (Phaseolus vulgaris L.) background using linked molecular marker SY20

Abstract

French bean is one of the most important staple foods in many parts of the world. Among several bacterial, fungal and viral diseases, anthracnose caused by Colletotrichum lindemuthianum is the most widespread and severe disease of French bean. Therefore, the present study was undertaken as prebreeding effort with the objective of introgression of important bean anthracnose resistance gene Co-4 in elite cultivar. Hybridization between resistant genotype, TO having bean anthracnose resistance gene Co-4 and elite cultivar Arka Komal was done. Cross Arka Komal × TO was further advanced to generate, F1, BC1F1, BC2F1 and BC2F2 plants. Testing of hybridity of the resultant F1, BC1F1, BC2F1 and BC2F2 plants/pods using gene linked SCAR marker SY20 resulted in identification of 46 gene-positive BC2F2. Further foreground selection revealed lack of segregation for the target gene Co-4 in 16 progenies. Screening of these 16 homozygous progenies (Co-4 gene) following detached pod and germinated seed dip methods using race 3 of C. lindemuthianum validated Co-4 imparted resistance in all the 16 BC2F3 progenies. Agronomic evaluation of 16 Co-4 gene-positive BC2F4 progenies for 8 qualitative traits and 9 quantitative traits led to identification of AKTO 4, AKTO 5, AKTO 7 and AKTO 43 progenies as having better elite background. These can either be used as donors of resistance gene for further introgression and gene pyramiding or can further be advanced following backcrossing to develop essentially derived variety of elite parent, Arka Komal.