|Hughs, Sidney - Hughs Ed|
Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/1/2005
Publication Date: 6/24/2005
Citation: Zhang, J., Lu, Y., Cantrell, R.G., Hughs, S.E. 2005. Molecular marker diversity and field performance in commercial cotton cultivars evaluated in the southwestern USA. Crop Science. 45:1483-1490. Interpretive Summary: Recent reports have indicated that modern cotton cultivars have small genetic diversity. This would limit future efforts to improve cotton cultivars by selection for improved traits. This is a report on a project to evaluate the genetic differences between a selection of 24 current commerical cotton cultivars, and to determine if there is sufficient genetic diversity to use these cultivars in breeding for future cotton improvement. Genetic differences between the cultivars as determined by established genetic tests and evaluation methods indicated that significant genetic differences do exist between the selected cultivars. These genetic differences are sufficient to be able to select for improved yield and fiber quality in future breeding programs.
Technical Abstract: Genetic diversity in modern upland cotton cultivars (Gossypium hirsutum L.) is thought to be narrow, thus limiting genetic advance. Robust information on the genetic relatedness among currently grown cotton cultivars is lacking. The objectives of the present study were to field test a sample of elite commercial cotton cultivars, including many transgenic cultivars representing the major cottonseed companies, and to evaluate their genetic divergence using simple sequence repeat (SSR) markers. Eighty-eight SSR primer pairs were chosen for genotyping that provided 177 SSRs. Jaccard’s genetic similarity coefficients among 24 genotypes ranged from 0.694 to 0.936, with an average of 0.772, indicating that sufficient genetic diversity does exist within our sample of commercial upland cotton. Genetic similarities among cultivars from the same seed companies were generally higher than the mean of all cultivars and grouped into six major groups: two Deltapine (DP), one Stoneville (ST), one FiberMax (FM), and two New Mexico (NM) Acalas. One California Acala cultivar of New Mexico origin, developed by Phytogen (PHY), did not group with New Mexico Acala germplasm. Texas High Plains stripper type cultivars were distant from picker types and formed independent groups. Under New Mexico growing conditions, DP and ST cultivars yielded higher but produced lower fiber quality, while NM Acala cotton had lower yield but higher fiber quality. The PHY and FM cultivars were intermediate in cotton yield and fiber quality. Six SSR markers were identified to be significantly correlated with fiber yield or quality among the cultivars tested, providing impetus to validate the marker–trait associations.