Genetic variability for number of elongating fibre cells in cotton (G. hirsutum, L.)

Germplasm and Genetic Stocks

poster

Sangannavar , Prashanth, A; Gamangutti, Savita; Hiremath, Vamadevaiah; Khadi, Basavaraj; Katageri, Ishwarappa

Katageri, Ishwarappa

Cotton fibre is an unique in nature as it is a single cell known so far as longest in length. The fibres are the out growths of few cells (15-20%) from the surface of the epidermal layer of cotton seed (ovule). There are two classes of seeds in cotton viz., fuzzy seeded cotton with fibres and fuzziless with fibres. In one class, called fuzz, epidermal cells just initiate to elongate but do not go beyond 5 mm (Stewart 1975). They represent about 80% in fuzzy type of seed. Remaining cells of about 20% are known to elongate beyond 5mm and go upto 40mm.Varities of G.hirsutum, G.herbaceum and G.arboreum fall in this class. In fuzzy less type of seeds,there are no short fibres,initiated cells (15-20%) elongate beyond 5mm -45mm.Genotypes of G.barbadense fall in this class. Proportion of cells elongating from epidermal cells of a cotton ovule determines the economic value of cotton in terms of lint yield expressed as ginning out turn. Higher the ginning out turn, higher the lint yield (cotton excluding seeds). In the present study, we found the presence of genetic variability for number cells to elongate into fibre from the cross between normally linting cotton genotype (38% GOT) and lintless cotton (0.01% GOT). Based on F2 data during 2010-11 at Agricultural Research Station Dharwad (INDIA), it is concluded that fibre cell elongation is the result of interaction between two independent genes (dominant duplicate gene interaction, 15 fibred :1 fibreless) classifying plants in two phenotypic groups viz., fibred (irrespective of number of cells elongated) and fibreless. As many as 147 F3 progenies were evaluated at the same location during 2011-12. All plants of eight progenies derived from eight F2 plants which were fibreless were also fiberless in F3. All plants of 108 progenies were fibred. In fully fibred plants, counting number of cells was not possible and considered as many fibres per 9.0 sq.mm. Segregation for number of cells elongating was observed in 31 progenies. As many as 91 plant’s seeds were observed for number of cells elongated and were grouped into 5 phenotypic classes. The another group was the fully fibred plants. Number of cells elongating into fibre (more than 10 mm long) per 9 sq. mm on matured seed surface was recorded under steareomicroscope ( Labomade Make) at 50x magnification.The range of number of elongating cells varies from 20-30, 31-40,41-50,51-60, 61-70,71-80 per 9.00 sq.mm. The ginning out turn (proportion of lint in seed cotton which is positively correlated to number of elongating cells per unit area) is also recorded. Ginning out turn was in the range between 0.01 -42 percent across the group. Length of the fibre also determines the ginning out turn. Presence of genetic variability for GOT visa visa number cells per unit area and length of those elongated cells was recorded. These lines will be of immense use to identify diverse genes involved in determining the number cells to be elongated through transcriptome/proteome studies. Diversity due to SNPs can also be detected for the genes.