The Effect on Wheat of an Agropyron Chromosome Carrying Rust Resistance

Introduction T h e transfer of specific characters from Agropyr07t species to wheat (Triticz~w) has frequently been attempted. In North America the emphasis has been on resistance to diseases such as bunt (Tilletia sp.), Larter and Elliott (1956); stem and leaf nlst (Pz~ccinia grmzinis tl-itici Erilts. and Henn. and Pzrccivzia recondita Erilts. and Henn.), Caldwell et al. (1956), Knott ( 1961), Schlehuber and Sebesta (1959), Schmidt et al. (1953), Smith et nl. (1960); and streak n~osaic, Schmidt et nl. (1956) and Swal-~lp et a1. (1956); to mention just a few studies. A wheat-Apopyro7z derivative (P.W. 327) having a modal chromoson~e number of 56 was produced by Shebeslti (Shebeslti and Wu , 1952) from the cross, Chinese x (Chinese X Agropyron elo7zgatunz (Host.) Beauv.). A n A g o p y r m chron~osome carrying a gene(s) for stem rust resistance was transferred fro111 P.W. 327 to the Thatcher variety of common wheat (T r i t i c z~~~z nestivz~w? L.) by Knott (1961). In the course of the transfer suitable material was obtained for a study of the effect of the Agl .opy~o~t chromoso~ne on both plants and gametes. T h e usefulness of the Agopyron rust resistance could depend to a considerable degree on the effect of the chromosome when transferred to wheat. Materials and Methods In the progranl to transfer stem rust resistance from P.W. 327 to Thatcher, plants having the following metaphase chromosome configurations were obtained 20 + 1'A ( A Ag~opyro7z chromoson~e), + 1'A and 20 + 1' + I'A. Addition lines (21 + 1A) and substit~ltioll ines (20 + 1A) werc also available. All plants carrying the Ag-l-opyron chromosome were resistant to race 15B of stem rust and in segregating material the distinction betwcen resistant and susceptible plants was clearcut. Ten substitution lines and three addition lines were given agronomic and quality tests for two years. Thatcher was used as a check and was entered hvice in cach test. In order to malce up a 16-variety balanced lattice, Sellcirk was added to the test in 195s and an extra substitution line in 1959. Neither is included in the results. In 1958 the plots were hvo rows, 12 feet long and in 1959 four rows, 12 feet long with only the centre two being harvested. A protein test (Kjeldahl nitrogen determination) was run on the 1958 seed and a full milling (Buhler mill) and balcing test on the 1959 seed. T h e quality results were obtained through the courtesy of Dr. C. C. Lee, Department of Chemistry, University of Saslcatchewan. . T w o substitution lines were crossed with the 21 niollosomic lines of Chinese Spring wheat, developed by Sears (1954). A~leiosis in the F, plants was examined to determine w~hich pair of wheat cl~romosomes had been replaced by an Agropyrost pair. The transinission of the Agl-opyron chromosome through both the male and female gametes was studied in plants of the three types in a univalent