Hybridization between resistant and susceptible fenugreek accessions and evaluation of Cercospora leaf spot resistance in segregating generations

Abstract

Cercospora leaf spot (CLS), caused by Cercospora traversoana, is an important phyto-pathological problem of self-pollinated fenugreek (Trigonella-foenum graecum). Developing resistant genotypes in crop plants has been considered the best option to control diseases for economic, environmental, and social reasons. However, before this can be accomplished, knowledge about the inheritance of disease-resistant genes is necessary for creating high-yielding resistant genotypes. One susceptible fenugreek cultivar, Tristar, and two resistant accessions L3717 and PI138687 were used in two-way crosses using hand emasculation and pollination technique in a greenhouse. F1 plants were grown in a greenhouse and allowed to grow till maturity to produce F2 seeds. Some flowers from F1 plants were crossed back to both resistant and susceptible parents separately to generate backcross (BC1) seeds. Parents, F1, F2, and BC1 populations were grown in the greenhouse using a RCBD with four replications. Plants were inoculated 30 d after sowing with a suspension of C. traversoana at 2 × 105 conidia mL−1. Symptoms were observed and rated on individual plants 25 d after inoculation, and plants were categorized according to susceptible or resistant reactions based on rating scores. Mean disease score was significantly different (p < 0.0001) among generations. In both the cross combinations, results showed CLS resistance in fenugreek (from L3717 and PI138687) was governed by a single dominant gene which is moderately heritable (46% narrow sense heritability). This indicates a relatively simple pathway for transfer of genes to adapted fenugreek cultivars.