SUPPRESSION OF HOMOEOLOGOUS PAIRING IN HYBRIDS OF POLYPLOID WHEATS X TRITICUM SPELTOIDES

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Abstract
Homoeologous pairing in hybrids of Triticum aestivum x T. speltoides (Aegilops speltoides) was increased by deficiency for chromosome arm 5BL, which carries an inhibitor of somatic association, and decreased by deficiency of 5BS, which promotes somatic association. It is suggested that speltoides carries a promoter of somatic accociation which is similar to the gene on wheat chromosome 5D rather than a suppressor of the 5BL gene. It adds to the effect of the 5D gene and the genes of 5AL and 5BS in counteracting the inhibitor of somatic association of 5BL. High temperature, which did not affect homologous pairing in T. durum x T. monococcum, reduced homoeologous pairing in hybrids of polyploid wheats (T. durum and T. aestivum) x T. spelotides. The greatest effect was observed after 4 days. It is suggested that suppression of meiotic pairing by high temperature is caused by a temperature shock on a critical stage prior to meiosis. The shock presumably relaxes somatic association.