Lei Ye^2* , Zhiguang Shi^1* , Pengtao  Gong³ , Yongqi Li³ , Xuanjun  Fang³

1. College of Life Sciences, Guizhou University, Guiyang, 550025;
2. College of Life Science and Technology, Guangxi University, Naning, 530005;
3. Haide Institute of Tropical Agricultural Resources (HITAR), Sanya, 572025
* These authors contributed equally to this work
Author    Correspondence author
Cotton Genomics and Genetics, 2010, Vol. 1, No. 1   
Received: 20 Jun., 2010    Accepted: 10 Sep., 2010    Published: 01 Jan., 1970

This article was first published in Fenzi Zhiwu Yuzhong (Molecular Plant Breeding) in Chinese, and here was authorized to translate and publish the paper in English under the terms of Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

 In present study, the four cotton germplasms with significant differences in fiber traits, Bollgard DP 99B (full haired seed, upland cotton, Gossypium hirsutum L.), ZYS20 (fuzzless seed, upland seed, G. hirsutum L.), FLS2123 (fuzzless-lintless seeds or bare seeds, upland cotton, G. hirsutum L.), and VH8 (fuzzless seed, sea island cotton, G. barbardense L.) were employed as the experimental materials of cotton to develop the genetic populations by making four crosses, their hybrid combinations were: DP99B×FLS123, DP99B×ZYS20, ZYS20×FLS123, and DP99B×VH8. In February of 2007, we harvested their F₁ hybrid seeds of four combinations planted in the October of 2006, and F₂ segregating generation seeds harvested in the May of 2007. The fiber traits of F₁ seeds and F₂, seeds were phenotyped in order to figure out the genotypes conferring  differentiation and development of of cotton fibrils on lint and fuzz.

Based on the results of F₁ fiber phenotypes and F₂ fiber segregating phenotypes, we presumed that the lint genotypes of the tested four parents as follows: the genotype of DP99B could be Li^ALi^A  or Li^A li^A and Li^DLi^D or Li^D li^D; as well as the genotype of ZYS20: Li^ALi^A or Li^A li^A and Li^DLi^D or Li^D li^D; the genotype of FLS2132: li^A li^A li^D li^D; the genotype of VH8: Li^ALi^A or Li^A li^A and Li^DLi^D or Li^D li^D. The results showed that cotton lint length showed a good normal distributions in all tested F₂ populations, which implied that the development of cotton lint should be controlled by complex quantitative trait loci. For the genotypes of fuzz in the F₂ populations of the four crosses, there were no any segregating photypes in the crosses of ZYS20×FLS2132 and DP99B×VH8, the F₂ population derived from ZYS20×FLS2132 were only the phenotype of fuzzless seed, while the F₂ population derived from DP99B×VH8 were only the phenotype of full haired seed. Whereas the F₂ generations derived from the crosses of DP99B×FLS2132 and DP99B×ZYS20 were segregated in differences. Therefore the fuzz genotypes of the four parental germplasms were presumed as follows, the possible fuzz genotypes of DP99B could be ii, susu, Ft1Ft1, Ft2Ft2, Ft3Ft3, FcFc and ii, susu, Ft1Ft1, Ft2ft2, Ft3ft3, Fcfc, as well as the possible fuzz genotypes of VH8: Ii, Susu, Ft1Ft1, Ft2Ft2, Ft3Ft3, FcFc and Ii, susu, Ft1Ft1, Ft2Ft2, Ft3Ft3, FcFc, the possible fuzz genotypes of ZYS20: Ii, Susu, Ft1ft1, Ft2ft2, Ft3ft3, Fcfc, Ii, susu, Ft1ft1, Ft2ft2, Ft3ft3, Fcfc and ii, Susu, ft1ft1, ft2ft2, Ft3Ft3, fcfc, the possible fuzz genotypes of FLS2132: II, SuSu, Ft1ft1, Ft2ft2, Ft3ft3, Fcfc and Ii, Susu, Ft1ft1, Ft2ft2, Ft3ft3, Fcfc. These results implied that the loci controlling the fibril differentiation of fuzz and lint might be located on different genomes of cotton.

Meanwhile, we further inferred that the genotypes of the F₁ fibrils of fuzz as follows, the genotype of the F₁ derived from DP99B×VH8 combination could be as ii, susu, Ft1Ft1, Ft2Ft2, Ft3Ft3, FcFc, which generate full haired seed of F₁ seeds and no phenotype of fuzz segregating in the F₂ generation.  The genotype of the F₁ derived from DP99B×ZYS20 combination could be as ii, susu, Ft1ft1, Ft2ft2, Ft3ft3, Fcfc or ii, Susu, Ft1ft1, Ft2ft2, Ft3ft3, Fcfc, which generate full haired seed of F₁ seeds and phenotype of fuzz segregating in the F₂ generation The genotype of the F₁ derived from DP99B×FLS2132 combination could be as Ii, Susu, Ft1ft1, Ft2ft2, Ft3ft3, Fcfc or Ii, susu, Ft1ft1, Ft2ft2, Ft3ft3, Fcfc, which generate fuzzless seed of F₁ seeds and phenotype of fuzz segregating in the F₂ generation. The genotype of the F₁ derived from ZSY20×FLS2132 combination could be as II, SuSu, Ft1ft1, Ft2ft2, Ft3ft3, Fcfc, which generate fuzzless seed of F₁ and no phenotype of fuzz segregating in the F₂ generation.

According to statistical analysis of the data for the lint length and fuzz density of cotton seeds a for statistical analysis, there was a correlationship between the density of fuzz and lint length of cotton, that is in case of both of lint and fuzz existing in the cotton seed, the longer of the lint length and the greater the lint density they are, the greater of the fuzz density and distribution are. It can be confirmed that once the differentiation of fuzz cell came out from the ovule, the development of fuzz and lint might be synchronous and be controlled by a series of common genes.

The study concluded that there are significant interactions exsiting between the genes controlling development of lint and fuzz. The genes controlling the lint development might have some epistatic genetic effects on the genes controlling fuzz development. When the ovule epidermal cells differentiate into whatever types of cotton fibers, then the development of cotton fiber elongation will be controlled by the same serial genes. Once the fuzz fiber cells are differentiated, while the genes cotrolling the lint will simultaneous regulate the distribution and density of fuzz. 

Cotton (Gossypium spp); Full haired seed; Fuzzless seed; Fuzzless-lintless seed; Lint; Fuzz; Differentiation and development of fibers genotype analysis