Gamma-rays induced reciprocal translocation in nigella damascena l. (love-in-a-mist)

Abstract

Gamma irradiations (5, 10, 15 and 20 kR) to Nigella damascena L. (love-in-a-mist; family: Ranunculaceae) seeds (moisture content: 8.7%) induced three viable translocation heterozygotes (P-3 and P-15 from 5 kR and P-25 from 10 kR) which on selfing yielded progeny heterozygotes in subsequent generations (R2, R3 and R4; however, P-15 could only be assessed upto R2 generation) exhibiting the formation of either a ring or a chain of four chromosomes in 14.8–54.6% meiocytes. Mean quadrivalent frequency per cell was assessed to be 0.40–0.66 in P-3, 0.43–0.64 in P-15 and 0.15–0.47 in P-25. Configuration and orientation of the multiples in the heterozygotes assessed over the generations indicated a possible genetic control over the mechanism. Normal 6/6 separation of chromosomes at AI (55.86–100.00%) of the heterozygotes did not correlate significantly (r = 0.29,27 DF) with pollen fertility (6.98–46.38%). Pollen fertility showed negative and insignificant correlation (r = -0.20,27 DF) with seed set per plant (0.0–495.0). Total failure of seed setting in heterozygotes has been attributed to defective female gametogenesis. F1S raised from intercrossing (R,) of P-3, P-15, and P-25 were meiotically assessed and the results indicated that the same two non-homologous chromosomes were involved in translocation and the two longest chromosome pairs A1A1 (nucleolar pair) and A2 A2 were suggested to be associated. © 2006 Taylor and Francis Group, LLC.