Abstract
1. A new type of progressive chlorosis was found to occur in reciprocal F1 hybrids between Triticum dicoccum cultivar Hokudai (2n=28, genome formula AABB) and T. timopheevi var. typicum strain NIG (2n=28, AAGG); it was named “chlorosis type 2”.
2. Two complementary genes cause chlorosis type 2; they were designated by Chl1 and Chl2. T. dicoccum cultivar Hokudai carries Chl1 on a chromosome in A or B genome, while T. timopheevi strain NIG possesses Chl2 on a chromosome in G genome.
3. Other 19 emmer strains belonging to three different species carried only chl1 gene, while all 13 strains of T. timopheevi possessed Chl2gene; the species, T. timopheevi, is distinctly different from emmer wheat as to its population structure for the chlorosis genes.
