Monosomic and Conventional Gene Analyses in Common Wheat

Abstract

Genetic control of growth habit and awnedness in common wheat was studied by the aneuploid and the conventional methods of analysis. Using the 21 monosomic lines of the spring variety, Chinese Spring, as female parents, crosses were made with seven varieties. In addition, diallel crosses were made among the seven varieties and Chinese Spring.Growth habit was found to be controlled by genes belonging to three allelic series Sg1, Sg2 and Sg3, located on chromosomes XVIII, IX and XIII, respectively. The Sg1 and Sg2 series appeared to have three alleles and the Sg3 series had two alleles; the alleles being Sg1, Sg1c and sg1, Sg2, Sg2c and sg2 and Sg3 and sg3 in order of dominance for each series.Genotypes of the eight varieties are proposed, namely, sg1 sg2 Sg3 for Elgin, Kharkov and Jones Fife, Sg1c Sg2c Sg3 for Chinese Spring, Sg1c Sg2 Sg3 for Red Egyptian, Sg1 Sg2c Sg3 for S-615 and Sg1 Sg2 sg3 for Prelude and Red Bobs.All winter varieties studied carried the typical winter habit genes, sg1 and sg2. The gene sg1 was much more effective than sg2 in delaying heading. Spring varieties carried some of the less effective spring habit genes, Sg1c, Sg2c or sg3 instead of the typical spring habit genes, Sg1, Sg2 or Sg3.Concerning awnedess, monosomic analysis revealed that awnlessness of Chinese Spring is ascribed to two inhibitors Hd and B2 on chromosomes VIII and X, respectively while that of Red Bobs to the presence of inhibitors B1 on chromosome IX and B2 and the absence of the a1 promotor on chromosome II; awnlettedness of Elgin and Jones Fife is controlled by the B1 gene; and awnedness of Prelude, Kharkov, S-615 and Red Egyptian is due to absence of all inhibitors. Conventional analysis confirmed the results obtained by monosomic analysis and indicated that an inhibitor on chromosome XVI of Chinese Spring affected F2 segregation of awnedness when crosses were made between Chinese Spring and other varieties.