In this association mapping study, a tri-species hybrid, [Gossypium arboreum × (G. hirsutum × G. aridum)2], was crossed with MD51ne (G. hirsutum) and progeny from the cross were used to identify and map SSR markers associated with reniform nematode (Rotylenchulus reniformis) resistance. Seventy-six progeny (the 50 most resistant and 26 most susceptible) plants were genotyped with 104 markers. Twenty-five markers were associated with a resistance locus that we designated Renari and two markers, BNL3279_132 and BNL2662_090, mapped within 1 cM of Renari. Because the SSR fragments associated with resistance were found in G. aridum and the bridging line G 371, G. aridum is the likely source of this resistance. The resistance is simply inherited, possibly controlled by a single dominant gene. The markers identified in this project are a valuable resource to breeders and geneticists in the quest to produce cotton cultivars with a high level of resistance to reniform nematode.

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Cottonseed is a rich source of high quality protein, but its value as an animal feed is limited by gossypol, a toxic polyphenolic compound contained in glands located throughout the plant. This compound helps protect the plant from pests. Totally glandless varieties have been developed, but not adopted as these plants are left vulnerable to pests. This study describes a breeding strategy to decrease the levels of gossypol in the seed while maintaining a high enough concentration of toxin in vegetative plant parts to offer protection from pests. Preliminary studies indicated that crosses between varieties with different gland densities and distributions produced a range of glanding patterns. By selecting within the resulting progeny, we have identified F 7 generation progeny that have <0.30% total gossypol in the seed, while still possessing glands at critical locations on the vegetative plant parts. These new lines will be a valuable source of germplasm for developing low seed gossypol varieties. Seed from these varieties would provide a new source of inexpensive protein for animal feeding rations.

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A set of five upland (Gossypium hirsutum L.) cotton germplasm lines, GVS1 (Reg. No. GP‐947, PI 663886), GVS2 (Reg. No. GP‐948, PI 663887), GVS3 (Reg. No. GP‐949, PI 663888), GVS4 (Reg. No. GP‐950, PI 663889), and GVS5 (Reg. No. GP‐951, PI 663890) were developed and released by the USDA–ARS, Stoneville, MS in August 2009. These five lines include three semi‐glanded lines (GVS1, GVS2, GVS3) with varying gland densities and seed gossypol content, one glanded line (GVS4), and one glandless line (GVS5); all five are in the same genetic background Stoneville 7A (PI 529228). In the F11, the seed gossypol content of GVS1, GVS2, and GVS3 was 0.81, 0.49, and 0.50% of the total seed weight, respectively. The parental line Stoneville 7A had 1.54% and Stoneville 7A glandless had 0.00% seed gossypol. The near‐isogenic lines GVS4 and GVS5 had 1.51% and 0.00% seed gossypol. GVS1, GVS2, and GVS3 have stem glanding similar to the glanded parent. Calyx glanding is normal in GVS1 and GVS3, whereas GVS2 had a 17% reduction. Boll glanding scores were 67% (GVS1), 60% (GVS2), and 59% (GVS3) of the glanded parent. In the semi‐glanded lines, leaf glanding was reduced at the end of the season, but the leaves were always glanded on veins and margins. Yield and fiber properties were measured. These lines will be valuable tools for mapping, for host‐plant resistance studies, and as a resource to develop low‐seed‐gossypol lines.

Background: Cotton (Gossypium hirsutum L) is an important crop worldwide that provides fiber for the textile industry. Cotton is a perennial plant that stores starch in stems and roots to provide carbohydrates for growth in subsequent seasons. Domesticated cotton makes these reserves available to developing seeds which impacts seed yield. The goals of these analyses were to identify genes and physiological pathways that establish cotton stems and roots as physiological sinks and investigate the role these pathways play in cotton development during seed set.

Cotton (<i>Gossypium hirsutum</i> L.) produces a number of toxic terpenoid aldehyde (TA) compounds contained in epidermal glands that help protect the plant from pests and diseases. In the seed, one of these toxic compounds, gossypol, limits the use of the seed to ruminants such as dairy cows. There are breeding techniques and germplasm available to decrease gossypol in the seed, but the breeding process also needs to include methods to evaluate the plant’s ability to resist insect pests. Three approaches were used to assess resistance of cotton to herbivory from bollworm (<i>Helicoverpa zea</i> Boddie) and tobacco budworm (<i>Heliothis virescens</i> F.) including field counts, controlled field antibiosis assays and laboratory feeding tests of young field grown leaves. Results indicated that both field and laboratory evaluation could provide an assessment of the cotton host’s resistance. Measurements of terpenoid aldehydes (TAs) in the seed and the leaves, confirmed that the levels and types of TAs in the seed were not always good estimators of leaf TAs and that other TAs such as hemigossypolone and heliocides contribute to host plant resistance

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