INHERITANCE IN HEXAPLOID WHEAT OF LEAF RUST RESISTANCE AND OTHER CHARACTERS DERIVED FROM AEGILOPS SQUARROSA

Abstract

T h e inheritance of seedling leaf rust resistance and several morphological characters derived from Aegilops sqzlnrrosn (211 = 14 = D D ) was investigated in a synthetic hexaploid wheat. T h c hexaploid was obtained by combining the tetraploid component (211 = 28 = A A B R ) extracted from thc colnmon whcat cultivar Canthatch with Ae. sqzlnrrosn 1 ar. nreyeri R.L. 5289.A major, partially dominant gene was identified that gives good resistance (typc 0;l rcaction) t o leaf rust races 1, 5, 9, 11, 15, 30, 58 and 126a. This gene was shown to bc diffcrent from the resistance genes L r l , Lr2, Lr5, LrlO, Lr16, Lr17 and LrlR. A minor second gene was also detected which gives resistance (typc 2 rcaction) to race 9 and slight resistance t o some of the other races. Each of the characters purple coleoptile, non-waxy foliage, brown glumes, and non-frce threshi~lg (tenacious glumes) of the synthetic wheat was monogenitally inhcritcd. T h c gcnc for threshability may be different from other genetic systcxns known t o affect this character. T h e gene for brown glumes was linked with thc n~a j o r gene for leaf rust resistance with a recombination value of 1.1 * 1.1%. Tllc genes for non-waxy foliage and non-free threshing were associated with an estimated linkage value of 15.1 * 2.6%.T h e results effcctivcly demonstrated thc relative ease with which genetic variation may bc incorporated into common hexaploid wheat from its ancestral diploid, Ae. sqmrrrosn, by means of a synthetic hexaploid intermediary. T h e n~cthod avoids thc difficultics and complications often encountered with the transfer of genes from morc distantly related species which d o not 11a\~e a genome in common with T. crestivrlt~~.

Suppression of powdery mildew resistance gene Pm8 in Triticum aestivum L. (common wheat) cultivars carrying wheat-rye tranlocation T1BL·1RS

“…However, numerous studies in Triticum have revealed that the expression of resistance is reduced when genes are transferred from lower to higher ploidy levels. This phenomenon of a 'dilution' of the resistance was reported by Kerber & Dyck (1969, 1979 for leaf rust, Trottet et at. (1982) for leaf and stripe rust, mildew and glume blotch, Gill et al (1986) for leaf rust, mildew, greenbug and Hessian fly, Chevre et a!.…”

Characterization of Synthetic Hexaploids Derived from Same <i>Aegilops tauschii</i> Accessions and Different Durum Cultivars

“…The dilution of leaf rust resistance was noted in amphiploids with T. durum when compared with the diploid resistant parent (Ae. tauschii) (Kerber and Dyck, 1969). The same also has been noted by Trottet et al (1982) with powdery mildew, leaf rust, yellow rust and glume blotch.…”

Genetic studies on .ALPHA.-amylase isozymes in wheat. III. Intraspecific variation in Aegilops squarrosa and birthplace of hexaploid wheat.

“…In their successful attempts, Kerber and Dyck (1969) and Dyck and Kerber (1970) could transfer the genes for leaf rust resistance to common wheat from two strains of Ae, squarrosa of KUSE collection. These are the practical examples demonstrating rather easy transfer of the desirable gene to common wheat from its wild relatives through genetic recombination.…”