| Role of chromosome 7D in the expression of seed colour
in bread wheat, Triticum aestivum L. D. C. SHARMA1) and J. G. BHOWAL Department of Genetics, Indian Agricultural Research Institute, New Delhi, India Although mono-, Di- and trigenic inheritance of seed colour in bread wheat has been reported by numerous investigators, precise location of all the genes influencing seed colour is still incomplete. One dominant gene, R1 was located by SEARS (1944, 1954) on right arm of chromosome 3D. In the present study seed colour was analysed in disomic F2 and monosomic F2 populations derived respectively after crossing the variety Cadet and its seventeen monosomic lines with the mexican dwarf wheat variety Sonora 64. Monosomic lines for chromosomes 1D, 6B, 6D and 7B were not ready for investigation. Both varieties Cadet and Sonora 64 and all the seventeen monosomics of Cadet have red grains. F2's from disomic and different monosomics of Cadet x Sonora 64 crosses were red grained. No segregation was observed in the disomic F2 and monosomic F2 populations except F2 of mono-7D (Table 1). chi2 test for 15 red grained vs. 1 white grained plants gave a close fit. F3 progenies of white grained plants were all white grained. Out of thirty randomly chosen F2 red grained plants, twenty were homozygous red, and remaining ten again segregated as 15 red vs. 1 white in F3 generation (Table 2). It should be mentioned that the white grained plants both in F2 and F3 populations of the critical cross did not appear to be nullisomics rejecting the notion that the chromosome 7D carries the gene for red kernel colour. However, it is quite apparent that there is a gene(s) on chromosome 7D of the variety Cadet absence of which allows the expression of the other seed colour genes (probably two) in recessive condition. Literature cited SEARS, E.R. 1944. Cytogenetic studies with polyploid species of wheat. II. Additional chromosome aberrations in Triticum vulgare. Genetics 29: 232-246. SEARS, E.R. 1954. The aneuploids of common wheat. Missouri Agr. Exp. Station Res. Bullettin 572: 59. (Received June 12, 1973) |
| 1) Present address: Dept. of Agronomy, Univ. of Wis., Madison, Wis., USA |