Meiotic Analysis in Pentaploid-Derived Aneuploids in Wheat

Meiotic analysis at metaphase I was carried out in pentaploid derived F₂ and BC₁ (pentaploid × hexapioid) generations of wheat. Chromosome number among the BC₁ aneuploids ranged from 2n = 35 to 2n = 42 as expected with 2n = 38 or 39 as the modal class. High frequency of euploid gametes indicates chromosome elimination from pentaploid egg cells or their selective advantage. Increase in intermediate numbers (2n = 38 or 39) may be due to preferential fertilization. The average number of D genome chromosomes transmitted from the female side was 3.12/gamete. Skewed distribution of aneuploids was observed in the E₂ generation and the modal D chromosome number transmitted through the female gamete was 1. It is inferred that all classes of gametes are formed but they do not function with the same frequency. One backcross followed by selfing is useful in selecting a cytologically stable plant in hexapioid × tetraploid crosses.