Cytogenetic Activity and Mode of Action of the Pairing Homoeologous ( Ph1 ) Gene of Wheat

The Ph1 (pairing homoeologous) gene of common wheat, the main factor responsible for the cytological diploid-like behavior of this polyploid species, has been a subject of intensive cytogenetic studies in the last three decades. This paper reviews the effects of Ph1 on chromosomal pairing and spindle microtubule dynamics. It presents data supporting the hypothesis that this gene exerts its effect at presynaptic stages, affecting the premeiotic alignment of homologous and homoeologous chromosomes, and thereby controls the regularity and pattern of pairing at meiosis