Changes in the fatty acids in seeds of interspecific hybrids between Brassica napus and Brassica juncea

Abstract

Mustard (Brassica juncea) accessions from Sri Lanka have a fatty acid profile (FAP) dominated by the undesired erucic acid. Therefore, it is necessary to develop B. juncea lines with canola-quality FAP, carrying reduced erucic acid (<1%) and increased oleic acid (>50%). To improve the FAP, B. juncea accessions were hybridised with spring-type canola (B. napus) varieties grown in Australia. Interspecific crosses between three B. napus cultivars (♂) and B. juncea accessions (♀) gave crossability of 50–65%. Embryo culturing on Lichter medium overcame post-germination barriers to obtain F1 plants. Culturing of ovules 21 days after pollination was successful and embryos were independent of hormones in the culture medium and directly developed into plants. Seeds of interspecific hybrids had a FAP different from parental values, particularly for oleic and erucic acids. The low oleic acid (13%) in B. juncea increased to 23–26% in hybrids and high erucic acid in B. juncea (41%) declined to 21–23% in hybrids. Linoleic and linolenic acids showed little variation from parental values. FAP of F1 hybrids shifted towards that of canola quality. The F2 seeds had zero erucic acid and high oleic acid similar to or exceeding the canola parent. Successful interspecific hybridisation of B. juncea and B. napus was confirmed by altered FAP and molecular markers. Embryo rescue in interspecific hybrids of B. juncea and B. napus is a simple, powerful biotechnological tool to increase genetic diversity and transcend species barriers to transfer desired genes, between the species. By implementing a crossing strategy, there is a potential to improve the FAP of Sri Lankan mustard towards the canola type.