Division of Genetics, I.A.R.I., Delhi-12
The location of genes for seedling reactions to race 21 and bio type 21A-1 was undertaken in the two wheat varieties Lerma Rojo and Sonora 64 through monosomic studies taking Chinese Spring monosomies as pistillate parents. In Lerma Rojo, the genes for seedling resistance to race 21 and biotype 21A-1 were located on 2D, 4A and 6A of which the resistance of the genes on 2D and 6A breaks down at slightly increased temperatures (65° F to 77° F). In Sonora 64 five chromosomes —1A, 4B, 5A, 6A and 6B were found to be involved in conditioning resistance.
