| Results From the cross involving monosomic 3D of var. Pb. C 591 and T. sphaerococcum, two types of F1 plants were observed with chromosome configurations of 20" + 1' (monosomic) and 21" (disomic) at first meiotic metaphase. F1 plants of the cross involving ditelocentric 3DL of var. Chinese Spring and var. T. sphaerococcum were found to have a meiotic chromosome configuration of 20" + 1' het. at first meiotic metaphase. Morphologically all the F1 plants resembled T. aestivum, except erectoid type of leaves, typical of spaerococcum leaf character. The F1 plants produced only red seeds. Although the monosomic F1 hybrids possessed one full 3D chromosome of T. sphaerococcum (but in hemizygous state) still they did not show T. sphaerococcum characters, confirming the contention of Sears (1947) that sphaerococcum gene (s) in single dose (hemizygous) is ineffective. Appearance of erectoid leaves in the F1 plants do not support the suggestion that this character might be the pleiotropic effect of sphaerococcum gene (S). From the observations on F1 plants, it could not be determined whether s locus is simple or complex. To analyse this, F2 population was raised. F2 Population obtained from both the types of F1 plants of cross involving monosomic 3D of Var. Pb. C591 and T. sphaerococcum was screened for seed colour to ascertain the location of gene governing red seed colour in T. sphaerococcum. It was found that monosomic F1 hybrids (2n = 41, 20" + 1') where chromosome 3D of sphaerococcum is present as a univalent produced plants with red seeds only in F2 while the F2 of disomic (2n = 42, 21") plants segregated for 3 red: 1 white seeded plants (Table 1). This observation confirmed that there is one dominant gene responsible for red colour grains in sphaerococcum and it is located on chromosome 3D. Data were recorded on the F2 population raised from the F1 plants of cross involving telocentric 3DL of var. Chinese Spring and T. sphaerococcum. Characters on which the data were taken included grain shape (Long vs spherical), spike length (Long vs short), peduncle length (Long vs short) and grain colour (Red vs white) and the results are summarised in Table 2. F2 segregating plants obtained were classified into two distinct classes, parental type (812 plants, morphologically sphaerococcum and aestivum types) and recombinant type (218 plants having hybrid characters of sphaerococcum and aestivum). The recombinant class (21.7%) consisted of plants with different sphaerococcum sub characters. These recombinants were classified into 4 main sub-classes - 1. Long peduncle-short spike-spherical grain and short peduncle-long spike-long grain. 10.58% 2. Long peduncle-long spike-spherical grain and short peduncle-short spike-long grain. 5.44% 3. Long peduncle-short spike-long grain and short peduncle-long spike-spherical grain. 1.84% 4. Long peduncle-long spike-long grain-white grain and short peduncle-short spike-spherical grain-white grain. 3.3% |
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