TAM 94L-25 Research Articles

Cotton (Gossypium hirsutum L.) mutants with reduced levels of palmitic acid (C16:0) in seed lipids

The objective of this study was to identify mutants of upland cottonseed (Gossypium hirsutum L.) with reduced levels of palmitic acid (C16:0) in the seed. The five parental populations that had been exposed to Ethyl MethaneSulfonate in 1997 or 2002 were initially screened for either herbicide tolerance or divergent fiber quality. Fatty acid composition were determined for five seed bulks from 140 M5 mutant lines in 2009 and 100 M6 partial seeds in 2010. Mutants with reduced levels of palmitic acid levels were isolated from TAM 94L-25 (PI 631440), Acala 1517-99 (Reg. No. CV-115, PI 612326) and TTU SCM3-7-3 (Reg. No.GS-4, PI 657942). Thirteen M6 single seeds with reduced levels of palmitic acid (17.9–19.6%) were intercrossed in the greenhouse. Ten of the single seed selections were designated as potential male parents and randomly crossed to three potential female parents to generate F1 plants and 21 F2 populations for allele testing. Based on these tests, five F2 populations with reduced levels of low palmitic acid, were selected for further evaluation. The development of mutant lines with reduced levels of palmitic acid in upland cotton was submitted for proprietary protection under U.S. Patent No. 20160222399.

EMS-mutated cotton populations suggest overlapping genetic control of trichome and lint fiber variation

The complex genetic and environmental control of lint fiber yield and quality of cotton has long motivated interest in whether information from genetically-simpler trichome variations might contribute knowledge salient to cotton improvement. To investigate this question, from 3164 M5 lines resulting from EMS mutagenesis of two Gossypium hirsutum breeding lines, TAM 94L25 and Acala 1517-99, 106 lines with leaf and stem trichome variations and 55 control lines were further studied to investigate associations between trichome variation and lint fiber development. Although only weak correlation was found between stem/leaf trichome and fiber traits, we still found that among nine fiber traits measured in replicated trials, lines with mutations affecting stem trichome development had significant alterations for seven traits in the TAM 94L25 mutants, and six in the Acala 1517-99 mutants. While the small number of leaf trichome mutants found offered only minimal statistical power to resolve differences, mutant lines had significant alterations for three of the nine traits in the TAM 94L25 mutants, and two in the Acala 1517-99 mutants. In summary, mutants in leaf and/or stem trichome development often have altered lint fiber characteristics, supporting the hypothesis that there is considerable overlap in the sets of genetic factors acting in the development of these analogous organs. Moreover, visual selection of trichome mutants may be an effective screen to identify potential new alleles affecting lint fiber development.

Identifying QTL for fiber quality traits with three upland cotton (Gossypium hirsutum L.) populations

Cotton fiber quality was quantitative trait, controlled by multiple genes. Identification of stable quantitative trait loci (QTL) effectively contributing to favorable fiber quality traits would provide the key basis for marker-assisted selection used in molecular breeding projects. Three upland cotton F2 populations were established with a common parent Chinese cultivar Yumian 1 and three American commercial cultivars/lines (Acala Maxxa, CA3084 and TAM94L-25), each of which had unique fiber quality characteristic that was favorable economically. Three whole genome genetic maps were constructed with 323, 302 and 262 SSR loci for population (Yumian 1 × Acala Maxxa), (Yumian 1 × CA3084), and (Yumian 1 × TAM 94L-25) respectively, spanning 1,617.2, 1,639.9 and 1,441.4 cM. Based on these genetic maps and three generation phenotypic data of fiber quality traits (F2, F2:3 and F2:4), 77 QTL were detected, including 19 for fiber length, 14 for fiber uniformity, 17 for micronaire, 10 for fiber elongation, and 17 for fiber strength. Among these QTL, 46 QTL were significant QTL and 31 were putative QTL, including that one QTL (qFL05.1) and four QTL (qFL23.1, qFM06.1, qFM06.2 and qFE25.1) were detected across three and two populations respectively; two QTL qFL10.1 (Yumian 1 × TAM 94L-25) and qFL15.1 (Yumian 1 × Acala Maxxa) were detected in three generations; qFM23.1, qFE18.1 and qFS21.2 detected in population (Yumian 1 × CA3084), qFE10.1, and qFS10.2 detected in population (Yumian 1 × TAM 94L-25), and qFS15.1 detected in population (Yumian 1 × Acala Maxxa), were all detected in two generations. Alleles underlying these stable QTL were valuable candidate gene for fine mapping, cloning, and favorable gene pyramiding projects. Our study also verified that QTL mapping of fiber quality traits using multiple populations with a common parent had higher efficiency compared to single population crossed with two parents and favorable alleles contributed to QTL effect could be conferred by parents with inferior fiber quality traits.

Alleles conferring improved fiber quality from EMS mutagenesis of elite cotton genotypes

Genetic improvements for many fiber traits are obtained by mutagenesis of elite cottons, mitigating genetic uniformity in this inbred polyploid by contributing novel alleles important to ongoing crop improvement. The elite gene pool of cotton (Gossypium spp.) has less diversity than those of most other major crops, making identification of novel alleles important to ongoing crop improvement. A total of 3,164 M5 lines resulting from ethyl methanesulfonate (EMS) mutagenesis of two G. hirsutum breeding lines, TAM 94L-25 and Acala 1517-99, were characterized for basic components of fiber quality and selected yield components. Across all measured traits, the ranges of phenotypic values among the mutant lines were consistently larger than could be explained by chance (5.27-10.1 for TAM 94 L-25 and 5.29-7.94 standard deviations for Acala 1517-99-derived lines). Multi-year replicated studies confirmed a genetic basis for these differences, showing significant correlations between lines across years and environments. A subset of 157 lines selected for superior fiber qualities, including fiber elongation (22 lines), length (22), lint percent (17), fineness (23), Rd value (21), strength (19), uniformity (21) and multiple attributes in a selection index (26) were compared to 55 control lines in replicated trials in both Texas and Georgia. For all traits, mutant lines showing substantial and statistically significant improvements over control lines were found, in most cases from each of the two genetic backgrounds. This indicates that genetic improvements for a wide range of fiber traits may be obtained from mutagenesis of elite cottons. Indeed, lines selected for one fiber trait sometimes conferred additional attributes, suggesting pleiotropic effects of some mutations and offering multiple benefits for the incorporation of some alleles into mainstream breeding programs.

Registration of TAM 94L-25-M24, TAM 94L-25-M25, and TAM 94L-25-M30 Mutant Upland Cotton Germplasm with Improved Fiber Length and Strength

Three putative mutant upland cotton (Gossypium hirsutum L.) germplasm lines, TAM 94L-25-M24, (Reg. No. GP-952, PI 664553), TAM 94L-25-M25 (Reg. No. GP-953, PI 664554), and TAM 94L-25-M30 (Reg. No. GP-954, PI 664555), were developed by the Cotton Improvement Laboratory, Department of Soil and Crop Sciences, Texas AgriLife Research and released in 2010. These lines were developed by treating the parent germplasm line, TAM 94L-25 (PI 631440), an upland cotton line with improved high-volume instrument (HVI) upper-half mean length (UHML), with the chemical mutagen ethyl methanesulfonate. TAM 94L-25-M24, TAM 94L-25-M25, and TAM 94L-25-M30 exhibited UHML and fiber bundle tenacity that exceeded that of the parent, TAM 94L-25. These three lines yielded as much or more than the M0 parent and exhibited other HVI fiber-quality parameters that were within acceptable ranges. TAM 94L-25-M24, TAM 94L-25-M25, and TAM 94L-25-M30 should be useful in creating cultivars with improved fiber length and strength.

Combining ability for fiber quality parameters and within-boll yield components in intraspecific and interspecific cotton populations

The major problem with the simultaneous improvement of yield with higher fiber quality is the negative association due to the linkage and pleiotropic effects between lint yield components and fiber quality parameters. The objectives of this research were to estimate the general combining ability (GCA) of parents and specific combining abilities (SCA) of hybrids for fiber quality parameters and within-boll yield components, and to determine the association of fiber quality parameters with basic within-boll lint yield components. In this study, eight cotton cultivars and 15 F1 hybrids obtained by crossing five lines and three testers in the line x tester mating system during 2006 were planted in a randomized block design with four replications in 2007. The predominance of non-additive gene action was estimated for all traits except for the upper half mean fiber length (UHM), fiber strength, and seeds per boll, which were controlled by an additive type gene action due to the high GCA variance. Among the parents, 'Askabat-100' and 'Carmen' were the best general combiners for fiber length, strength, and uniformity index (UI). Additionally, 'GW Teks' and 'Sahin-2000' were determined to be good combiners for lint weight per seed (L/S) and spinnable fibers per seed (F/S). The SCA effects showed that the best specific combination was 'Sealand-542' x 'Sahin-2000' and 'TAM 94L-25' x 'SG-125' for lint percentage, L/S, and lint weight unit per seed surface area. The most important fiber quality parameters, UHM, fiber strength, and UI, were negatively associated with the most basic within-boll lint yield components, L/S, and F/S.

Phenology Measurements and Fiber Associations of Near‐Long Staple Upland Cotton

Breeding for long staple, early maturing upland cotton (Gossypium hirsutum L.) genotypes is a criterion for many breeding programs. Vertical flowering interval, horizontal flowering interval, and boll maturation period of long staple cotton was studied in four field-grown experimental strains and three cultivars in 1998 and 1999 at College Station, TX. Phenological traits of earliness, fiber length development period (FLDP), and fiber quality characteristics, especially fiber length measurements, were evaluated. TAM 94L-25 and TAM 94M-14, near long staple breeding lines, exhibited agronomically acceptable vertical (VFI) and horizontal (HFI) fruiting intervals and a slightly longer boll maturation period (BMP) when compared with current and obsolete cultivars. Fruiting interval measurements, BMP, and FLDP were all positively associated. No associations among fiber length measurements and earliness components were noted. Positive correlations were detected between FLDP and advanced fiber information system (AFIS) upper quartile length of fibers by weight (UQLw) and high volume instrument (HVI) upper half mean fiber length (UHM) across these seven genotypes. Negative relationships were noted between BMP and fiber quality parameters, while FLDP was negatively associated with fiber maturity parameters. Breeding for long staple genotypes has been successful, resulting in lines that possess improved yield and fiber quality but without unduly delaying crop maturity.

Registration of TAM 94L-25 and TAM 94J-3 Germplasm Lines of Upland Cotton with Improved Fiber Length

Registration of TAM 94L-25 and TAM 94J-3 Germplasm Lines of Upland Cotton with Improved Fiber Length