Suppressors For Rust Resistance On Wheat And Specificity Of Suppression

Seedling rust resistances of nineteen Aegilops tauschii (DD) and thirty-six tetraploid wheats (AABB) were tested by using five races of Puccinia stri formis West. and four races of? recondita f. sp. tritici, respectively. As results indicated that most Aegilops tauschii. were resistance to all races for test and most tetraploid wheats were susceptible to them or some of them. Four susceptible diploids e.g. T96243. T96245.. Gatersleben 194.. Cambridge L.and ten resistance tetraploids e.g. G484-6M.. G503-2-l-6G. Norba.. Volcani447.. Tdicoccoides.. G-668.. G363-5M.. G3042.. G3051 and G3054 were screened which would be used for studying the suppressors for rust resistance on D genome by synthesizing hexaploid.The genes for resistance to stripe rust Yr5.. Yr6.. Yr7.. YrlO.. Yr15.. Yr24.. Yr26~. YrA and some unknown genes were postulated to be probably present in tetraploid wheats selected, either alone or in combination. By means of optimal RAPD reaction system, DNA of diploid Aegilops tauschii. (Ae39), tetraploid wheat (PS5) and synthetic haxaploid wheat (Axn5) derived from Ae39 and P55 were amplified. A total of fourty lO-mer random primers were screened,ofwhichtwelveprimerse.g.M02.. 5182.. 5186.. S187.. 5188.. 5190.. S193.. 5197.. 5199.. S202.. 5204.. S211 could amplify specific DNA fragments of D and AB genomes. Specific bands of D genomes and AB genome in four diploids, four tetraploids and four hexaploids, respectively, could be also amplified by means of M70/E5 1 and M711E5 1 primer combinations screened from twenty pairs of AFLP primer combination for test. Most primers amplified same bands in diploids, tetraploids and hexaploids. It suggest that D and AB genomes have high homology and D genomes be successfully transferred from diploid to hexaploid. Seedling infection types were detected in eight synthetic hexaploids and theirparents against five stripe rust races and four leaf rust races. The results indicatedtha D and A B genomes of Wheat possessed suPpressors for rust resiStance but morecomrnon on D genomes. Interactions betWeen suPpressors, resiStance genes and rustraces revealed that suPpressor had specificity toward resistance and differellt rustrace. Obviously, suPpressors are not expected in aghcultUre. Further works willstUdy the specific mechhasm of suPpressors of resiStance and their inheritance bycrossing between synthetic hexaPloids with a suPpressor and that without asuPpressor.