| Popis: |
We selected genotypes of high and low B chromosome transmission rate (TR) in a native race of maize (Pisingallo) from northwest Argentina. We made 20 female OB X male IB and 20 f.lB x m.OB crosses. The former (GOm) showed a large variation of B TR, with a mean of TR ? SE = 0.52 ? 0.06, ranging from 0.17 to 0.98. In the latter (GOf) the mean was TR = 0.47 ? 0.02 ranging from 0.31 to 0.58. Plants showing the highest and the lowest TR were selected to constitute the progenitors of the Gl generations. We made 19 f.OB x m.2B crosses, studying 24-30 plants per cross. The TR of the high (H) and low (L) lines in Glm (GlmH and GImL) significantly differed (TRH = 0.65 ? 0.03, TRL = 0.40 ? 0.01), indicating that the H and L lines are different groups. The large variation in male TR suggests that preferential fertilization of gametes carrying B chromosomes does not always occur. We also selected plants showing high and low TR in the progenies of f.lB X m.OB crosses (GOfD, and made 24 f.lB X m.OB crosses, studying 23-30 plants per cross. The TRs of the H and L lines in Glf (GlfH and G1fL) were significantly different (TRH = 0.48 ? 0.025, TRL = 0.40 ? 0.02). The TRs in GOf and GlfL were significantly different (TR = 0.47 ? 0.02 and 0.40 ? 0.02, respectively), while this was not the case between GOf and GlfH. Our results demonstrate the existence of genotypes controlling B TR in this native population of maize. |
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