Cytological stability of common wheats with leaf rust resistance derived from Triticum timopheevi Zhuk

Abstract

Nine common wheat strains derived from crosses involving Triticum timopheevi were studied for cytological stability and resistance to individual physiologic races of leaf rust of wheat. One strain 53R-201-4 was resistant to all the eleven races used. Another five stable strains had resistance to some of the races and were susceptible to others. Three highly unstable strains had resistance to a few of the leaf rust races used. The six stable strains had normal meiosis, varying between the most stable ‘Cheyenne’ and the less stable ‘Minturki’-the two checks. In general, the inheritance of resistance to leaf rust race 9 in crosses of three unstable and one stable strain was monogenic and regular. Metaphase I chromosome pairing and meiotic irregularities at anaphase-I, dyad and quartet stages in stable strain 55–2687 and in F1 and F2 plants from the cross strain 55–2687 × Cheyenne indicated only slight reduction in chromosome pairing or chiasma formation in the F1 plants. The F2 was meiotically less stable than the F1. The possible reasons for the increased meiotic instability of the F2 are discussed.