Bridging the Genetic Gap: Utilization of Wild Relatives and Landraces in Brassica juncea Improvement Programs

Brassica juncea (Indian mustard) is a vital oilseed crop cultivated extensively in South Asia and other parts of the world for its adaptability and nutritional value. However, its genetic base has been significantly narrowed due to prolonged selection for high yield and uniformity, rendering modern cultivars vulnerable to biotic and abiotic stresses. This review explores the critical role of underutilized genetic resources, specifically wild relatives and landraces in enhancing the genetic diversity and adaptive potential of B. juncea. Wild species such as Brassica fruticulosa, Sinapis alba, and Diplotaxis spp. possess genes for disease resistance, drought and salinity tolerance, and unique agronomic traits. Landraces, on the other hand, represent farmer-selected, locally adapted populations rich in resilience and quality attributes. Both genetic sources are instrumental for breeding climate-resilient and nutritionally enriched cultivars. The study discusses key breeding strategies including conventional approaches (hybridization, backcrossing, recurrent selection), molecular tools (QTL mapping, GWAS, marker-assisted selection, genomic selection), and cutting-edge biotechnologies such as CRISPR/Cas9 and omics platforms. The paper also highlights genome-wide studies that have identified domestication-related loci associated with flowering time and stress adaptation. Despite notable advances, the utilization of wild and landrace germplasm faces challenges like linkage drag, reproductive barriers, and insufficient pre-breeding infrastructure. Addressing these constraints through participatory breeding, public-private partnerships, and climate-smart breeding frameworks is essential. By integrating genetic diversity with advanced breeding tools, B. juncea improvement programs can be revolutionized to meet future demands of food security, sustainability, and climate resilience.