An indigenous germplasm of Brassica rapa var. yellow NRCPB rapa 8 enhanced resynthesis of Brassica juncea without in vitro intervention

Limited genetic diversity in Brassica juncea restricts the scope of its genetic improvement for important agronomic traits. Resynthesizing B. juncea through interspecific hybridization offers the scope of entrapping the variability of the progenitors in this species. However, crossing barriers in interspecific hybridization restricts the use of this avenue. Interspecific hybrids can be developed to a limited extent by embryo rescue. In search of wide compatibility traits for efficient interspecific hybridization, a wide variety of interspecific cross combinations were designed between Brassica rapa accessions and different accessions of Brassica nigra. The frequency of seed setting was compared in these crosses with and without embryo rescue of hybrids. A novel germplasm of B. rapa var. yellow sarson NRCPB rapa 8, when used as the female parent in wide hybridization with different accessions of B. nigra, efficiently generated F₁ hybrid seeds even without embryo rescue. Wide hybridization with NRCPB rapa 8 as the female parent resulted in a significantly higher seed set and recovery of amphihaploid hybrids. This unique germplasm resource could aid in the rapid resynthesis of B. juncea through interspecific hybridization without the need for skill-intensive tissue culture intervention. The germplasm has been registered in the National Gene Bank repository at the ICAR-National Bureau of Plant Genetic Resources, New Delhi, India, and is available to peers.