Replication of pistillate plants of Ricinus communis L. and investigation of the sex stability and genetic variation of the somaclones

The castor (Ricinus communis L.) pistillate lines are important for hybrid seed production and research on sex traits. This study aimed to replicate the pistillate line of castor plants and detect somaclonal variation. Pistillate plants were successfully propagated and pistillate plant stability and somaclonal variation were tested. For propagation, 66 axillary buds with 96.97% survival were cultured on three different media: initial culture medium, proliferation medium, and rooting medium. At the end of this procedure, 108 plantlets were obtained and successfully transplanted into the field with 50–70% survival. Sex expression of the somaclones and their F1/F2 progenies indicated that pistillate was stable in the somaclones of three genotypes, and male flowers could be induced in other genotypes by tissue culture. The percentage of pistillate plants in the F1 progeny obtained from female somaclones was higher (30.00–100.00%) than that in the progeny of its pistillate donors (26.67–50.00%) and the monoecious regenerations (0–5.00%). Two pistillate somaclones with a reverted monoecious plant were grown together in isolation, and yielded 91.11% and 100.00% females in the F1 progeny, and 76.10% and 75.00% females in the F2 progeny from their sibling crosses. The detection of somaclonal variation suggested that the somaclones derived from the same donor and with a stable pistillate trait showed no allelic variation at simple sequence repeat loci, whereas allelic variation was detected among individuals of somaclonal populations with instable sex expression. These results provide a useful approach for pistillate plant propagation and heterosis utilization in castor via a combination of tissue culture and conventional breeding.