Abstract

Various weedy amaranths have demonstrated the possibility of genetic exchange via interspecific hybridization. Normal meiotic events lead to the formation of normal tetrads and normal pollen while abnormal meiosis results in abnormal segregation of chromosomes in the tetrads resulting in macro and micropollen. Thus, pollen size can be used as an indirect measure of meiotic integrity. The purpose of this study was to examine the frequency of micropollen from putative F₁, BC₁, and BC₂ progeny of waterhemp and smooth pigweed crosses to determine if infertility in the hybrids could be attributed to abnormal meiosis. Significant variation was observed with respect to the occurrence of micropollen. The F₁ hybrids had the highest occurrence of micropollen, and highest percentage of abnormal tetrad formation. Problems in meiosis could be causing decreased fertility, but not complete sterility. However, backcrossing resulted in progeny with smaller percentages of micropollen, consistent with previous reports that fertility is restored in these progeny. This method allows for quick and cost effective method for determination of interspecific hybridization events.

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