Camalexin induction in intertribal somatic hybrids between Camelina sativa and rapid-cycling Brassica oleracea

Camelina sativa, a wild relative of Brassica crops, is virtually immune to blackspot disease caused by Alternaria brassicicola. Intertribal somatic hybrids were produced between C. sativa and rapid-cycling Brassica oleracea as a step toward the transfer of resistance to this disease into Brassica vegetable crops. The plants recovered were confirmed as somatic hybrids by flow cytometry and RAPD analysis. All hybrids showed a morphology intermediate between the two parents. Rooted plants grew in soil up to 4-5 weeks, and some produced sterile flowers. Two of three hybrids tested showed a high level of resistance to A. brassicicola. Resistance was correlated with the induction of high levels of the phytoalexin camalexin 48 h after inoculation, as in the resistant Camelina fusion partner. In contrast, susceptible somatic hybrids produced much lower levels of camalexin.