Possible Genetic Control of Induced Translocation Heterozygosity in Black Cumin, Nigella sativa L.

A translocation heterozygote (without any marker phenotypic trait) is screened in Nigella sativa L. (black cumin) following the exposure of dry seeds (moisture content: 5.0%) to 300 Gy gamma irradiations (one out of twelve). On selfing (53 seeds sown), one heterozygote is detected out of seven survived plants at R-2. Compared to 61, formation (2n=12) in PMCs of standard normal plants, the heterozygotes form either a ring or a chain quadrivalents in association to bivalents and univalents (2n=12) in 52.68% (R-1) and 30.07% (R-2) meiocytes. Ring configuration and adjacent orientation of the multiples are more found to occur predominantly in R-1 than R-2 heterozygote. Pollen grain fertility and seed setting are found to vary between the translocation heterozygotes irrespective of orientation of the multiples. From the prevalence of ring interchange complexes, it is presumed that the breakpoints are closer to centromere. Furthermore, configurations of the interchange complexes highlight the possibility of two longer pairs of chromosomes to be involved in reciprocal exchanges. A possible genetic control of translocation heterozygote is predicted.