ARS | Publication request: A new fuzzless seed locus in an upland cotton (Gossypium hirsutum L.) mutant

Submitted to: American Journal of Plant Sciences
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 10, 2012
Publication Date: June 1, 2012
Citation: Bechere, E., Turley, R.B., Auld, D.L., Zeng, L. 2012. A new fuzzless seed locus in an upland cotton (Gossypium hirsutum L.) mutant. American Journal of Plant Sciences. 3(6):799-804.

Interpretive Summary: Normal cottonseed is covered with lint and fuzz. Lint is a textile fiber whereas fuzz is a short fiber that is difficult to gin from the seeds. Fiber mutants with fuzzless seeds have been reported since early 1900s and these mutants have been used to detect and locate areas of the chromosome that control lint yield, fiber quality, seed traits and response to biotic and abiotic stresses. They gin faster and with less energy and have low short fiber contents and neps. (entangled fibers). Two of the most widely studied mutants are N1N1 and n2n2 which condition fuzzless seeds and are characterized by very low lint percent (7 and 21 %, respectively). Lint percent refers to the ratio of cotton lint to cottonseed that together make up the seed cotton that is picked. In 1997, commercial variety SC 9023 was treated with ethyl methanesulfonate, a chemical mutagenic agent and a mutant plant with fuzzless seed with tufts attached to one end of the seed was identified. Agronomic tests over the years and crosses with N1N1 and n2n2 showed that this is a new locus, not previously identified and is controlled by one recessive gene which we designated as n4tn4t. This mutant has lint percent as high as most commercial cultivars (38 to 40 %) and therefore can be used in cotton breeding programs to reduce short fiber contents and neps and also improve ginning efficiency.

Technical Abstract: Various fiber mutants of cotton have been reported since 1920. Two of the best characterized mutants are the naked seed loci, N1N1 and n2n2. Recently, a naked-tufted mutant called 9023n4t was developed from the cultivar SC 9023 through chemical mutagenesis. The objective of this research was to determine if the new mutant was allelic to either N1, or n2 or was a unique mutant in a new uncharacterized locus. In 1999, one M3 plant from SC 9023 with tufted partially naked seed coat (fuzzless) was identified. In 2004, 2006, and 2007 (at Lubbock, TX), 2007 (at College Station, TX), and 2011 (at Stoneville, MS), the homozygous naked seed mutant was evaluated with the non-mutated wild type parent (SC 9023) in replicated trials for agronomic and fiber traits. Crosses between the mutant and the wild type was made at Stoneville, MS in 2009.The F2 of this cross segregated into a 3 fuzzy : 1 fuzzless ratio indicating that the fuzzless trait in the mutant is controlled by a recessive locus. Allelism tests with N1N1, n2n2 and n3n3, lint percent, and fiber trait data indicated that the new locus in the mutant was uncharacterized and differs from the previously characterized fuzzless seed alleles in that it does not appear to decrease lint percent. We have tentatively designated this gene n4tn4t.