Synthesis of somatic hybrids (RCBB) by fusing heat-tolerant Raphanus sativus (RR) and Brassica oleracea (CC) with Brassica nigra (BB)

Abstract

Brassica carinata (BBCC), a potential oilseed crop for dry land agriculture, is sensitive to high temperatures during germination and early stages of growth, which thereby restricts the possibility of using the residual soil moisture available after the rainy season for its cultivation. To overcome this problem, a three-genome hybrid, RCBB, was synthesized using Raphanus sativus (RR) and Brassica oleracea (CC) as donor sources for the desired heat tolerance. Protoplasts of RC hybrids obtained through sexual crosses between R. sativus (female) and B. oleracea (male) were fused with protoplasts of Brassica nigra (BB) to produce RCBB somatic hybrids. The hybrid colonies regenerated with an average frequency of 7.6%. Twelve out of 36 hybrids grown to maturity were characterized for their nuclear and organelle genomes. While all the hybrids showed the presence of B. nigra chloroplasts, 10 of the hybrids showed B. nigra-specific mitochondria and two had Raphanus-spedfic mitochondria. The somatic hybrids could be backcrossed to B. carinata.