Executive Summary : | Cucumis sativus L., a major vegetable crop in India, faces numerous diseases, including Downy Mildew (DM), which can cause up to 100% yield losses in cucumber crops. Farmers have been using fungicides to combat DM, but this is expensive and environmentally hazardous. The development of disease-causing pathogens has led to the loss of stress-resistant features in cultivars due to selection pressure for greater yields, nutritional value, and organ size. Using host genetic resistance against DM is an effective and environmentally friendly approach. Stress-responsive genes can be transferred from promising lines with downy mildew resistance into elite cultivars. However, the fundamental knowledge of the molecular mechanisms underlying downy mildew resistance is still lagging, despite the presence of large genomic resources for Cucumis sativus. The continuous evolution of fungal pathogens due to fungicide use and changing climatic conditions poses a challenge to combat this problem. At Lovely Professional University, downy mildew resistance lines were crossed as male donor lines with susceptible lines as female parents to generate a F2 mapping population. The obtained F2 mapping population will be used to map downy mildew resistance genes using BSA-seq based and RNA sequencing approaches to identify potential candidate genes. The mapped genes can be used to reveal the underlying genetic mechanism of disease resistance, which can be cloned further using biotechnological tools. Multiple disease resistance genes can be introgressed into elite cultivars via gene pyramiding approaches, and identified molecular markers can be useful for marker-assisted selection and molecular breeding programs. |