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Cottonseed is an important source of protein, oil, and minerals for human health and livestock feed. Therefore, understanding the physiological and genetic traits influencing the nutrient content is critical. To our knowledge, there is no information available on the effects of leaf shape—curly leaf (CRL)—on cottonseed protein, oil, and minerals. Therefore, the objective of the current research was to investigate the effect of the curly leaf trait on cottonseed protein, oil, and minerals in cotton lines differing in leaf shape. Our hypothesis was that since leaf shape is known to be associated with nutrient uptake, assimilation, and photosynthesis process, leaf shape can influence seed protein, oil, and minerals. A two-year field experiment using two curly leaf lines (Uzbek CRL and DP 5690 CRL) and one normal leaf (DP 5690 wild type) line was conducted in 2014 and 2015 in Stoneville, MS, USA. The experiment was a randomized complete block design with three replicates. The results showed that both Uzbek CRL and DP 5690 wild type lines had higher seed oil, and nutrients N, P, K, and Mg than DP 5690 CRL. Calcium was higher in DP 5690 CRL for two years and protein was only higher than the parents in 2015. Consistent significant positive and negative correlations between some nutrients were observed, which may be due to environmental conditions, especially heat. This indicates that curly leaf trait may partially regulate the accumulation of these nutrients in seeds. The results demonstrated that leaf shape trait—curly leaf—can affect cottonseed nutritional qualities. This research is important to breeders for cotton selection for high seed oil or protein, and to other researchers to further understand the genetic impact of leaf shapes on seed nutritional quality. It is also important for scientists to use leaf shape as a tool for physiological, biochemical, and morphological research related to leaf development.

Our previous research, conducted under well-watered conditions without fertilizer application, showed that fuzziness cottonseed trait resulted in cottonseed nutrition differences between fuzzy (F) and fuzzless (N) cottonseed. Under water stress conditions, B mobility is further limited, inhibiting B movement within the plant, affecting seed nutrition (quality). Therefore, we hypothesized that both foliar B and water stress can affect B mobility, altering cottonseed protein, oil, and mineral nutrition. The objective of the current research was to evaluate the effects of the fuzziness seed trait on boron (B) and seed nutrition under water stress and foliar B application using near-isogenic cotton lines (NILs) grown in a repeated greenhouse experiment. Plants were grown under-well watered conditions (The soil water potential was kept between -15 to -20 kPa, considered field capacity) and water stress conditions (soil water potential between -100 and -150 kPa, stressed conditions). Foliar B was applied at a rate of 1.8 kg B ha(-1) as H3BO3. Under well-watered conditions without B the concentrations of seed oil in N lines were higher than in F lines, and seed K and N levels were lower in N lines than in F lines. Concentrations of K, N, and B in leaves were higher in N lines than in F lines, opposing the trend in seeds. Water-stress resulted in higher seed protein concentrations, and the contribution of cell wall (structural) B to the total B exceeded 90%, supporting the structural role of B in plants. Foliar B application under well-watered conditions resulted in higher seed protein, oil, C, N, and B in only some lines. This research showed that cottonseed nutrition differences can occur due to seed fuzziness trait, and water stress and foliar B application can alter cottonseed nutrition.

There is no information available on the effect of fuzzless seed trait on cottonseed nutrient composition (minerals, N, S, protein, and oil) under drought stress. The objective of this research was to investigate the effect of the fuzzless seed trait on cottonseed nutrients using four sets of near-isogenic lines (NILs). Each set consists of two lines that share the same genetic background, but differ in seed fuzziness (fuzzy, F; fuzzless, N). The near isogenic lines will enable us to compare the effect of the trait without confounding the genotypic background effects. We hypothesized that since the fuzzless trait involved in fiber initiation development, and was reported to be involved in biochemical, molecular, and genetic processes, this trait may also alter cottonseed nutrient composition. Results showed that NIL sets accumulated different levels of minerals in seeds and leaves, and the fuzzless trait (NF) in most of the lines altered seed and leaf mineral accumulations when compared with fuzzy lines (FN) or the control line. For example, K, P, Mg, Cu, and Na concentrations in seeds were higher in MD N and STV N than in their equivalent MD F and STV F lines. Leaf concentrations of Ca, K, Mg, S, B, Cu, and Fe in MD N lines were higher than MD F line. Lower levels of nutrients in seeds and leaves were observed under water stress conditions, especially Ca, Mg, N, and B in seeds. Generally and with few exceptions, seed protein was higher in fuzzy lines that in fuzzless lines; however, seed oil was higher in fuzzless lines than in fuzzy lines. Our research demonstrated that fuzzless trait altered the composition and level of nutrients in seed and leaves in well watered and water stressed plants. Differences in protein and oil between fuzzy and fuzzless seeds may indicate alteration in nitrogen and carbon fixation and metabolism. The differential accumulation of seed nutrients in this germplasm could be used by cotton breeders to select for higher cottonseed quality.

Background Cotton fiber length is an important quality attribute to the textile industry and longer fibers can be more efficiently spun into yarns to produce superior fabrics. There is typically a negative correlation between yield and fiber quality traits such as length. An understanding of the regulatory mechanisms controlling fiber length can potentially provide a valuable tool for cotton breeders to improve fiber length while maintaining high yields. The cotton (Gossypium hirsutum L.) fiber mutation Ligon lintless-2 is controlled by a single dominant gene (Li 2 ) that results in significantly shorter fibers than a wild-type. In a near-isogenic state with a wild-type cotton line, Li 2 is a model system with which to study fiber elongation. Results Two near-isogenic lines of Ligon lintless-2 (Li 2 ) cotton, one mutant and one wild-type, were developed through five generations of backcrosses (BC5). An F2 population was developed from a cross between the two Li 2 near-isogenic lines and used to develop a linkage map of the Li 2 locus on chromosome 18. Five simple sequence repeat (SSR) markers were closely mapped around the Li 2 locus region with two of the markers flanking the Li 2 locus at 0.87 and 0.52 centimorgan. No apparent differences in fiber initiation and early fiber elongation were observed between the mutant ovules and the wild-type ones. Gene expression profiling using microarrays suggested roles of reactive oxygen species (ROS) homeostasis and cytokinin regulation in the Li 2 mutant phenotype. Microarray gene expression data led to successful identification of an EST-SSR marker (NAU3991) that displayed complete linkage to the Li 2 locus. Conclusions In the field of cotton genomics, we report the first successful conversion of gene expression data into an SSR marker that is associated with a genomic region harboring a gene responsible for a fiber trait. The EST-derived SSR marker NAU3991 displayed complete linkage to the Li 2 locus on chromosome 18 and resided in a gene with similarity to a putative plectin-related protein. The complete linkage suggests that this expressed sequence may be the Li 2 gene.

The aim of this study was to identify and isolate genes that are differentially expressed in four selected cotton (Gossypium hirsutum L.) genotypes contrasting according to their tolerance to water deficit. The genotypes studied were Siokra L-23, Stoneville 506, CS 50 and T-1521. Physiological, morphological and developmental changes that confer drought tolerance in plants must have a molecular genetic basis. To identify and isolate the genes, the mRNA Differential Display (DD) technique was used. Messenger RNAs differentially expressed during water deficit were identified, isolated, cloned and sequenced. The cloned transcript A12B15-5, a NADP(H) oxidase homologue, was up regulated only during the water deficit stress and only in Siokra L-23, a drought tolerant genotype. Ribonuclease protection assay confirmed that transcription. O objetivo deste estudo foi identificar e isolar genes diferencialmente expressos em quatro genótipos de algodão (Gossypium hirsutum L.) que apresentam respostas distintas ao déficit hídrico. Os genótipos estudados foram Siokra L-23, Stoneville 506, CS 50 e T-1521. As mudanças fisiológicas, morfológicas e de desenvolvimento que as plantas apresentam para suportar a diminuição na disponibilidade de água tem, obrigatoriamente, uma base molecular genética. Utilizou-se a técnica de "Differential Display" para identificar e isolar os genes diferencialmente expressos. RNAs mensageiros diferencialmente expressos durante o déficit hídrico foram identificados, isolados, clonados e seqüenciados. O clone A12B15-5 apresentou homologia com uma NADP(H) oxidase e foi expresso somente durante o período de déficit hídrico em Siokra L-23, um genótipo de algodão tolerante à seca. O uso da técnica "Ribonuclease Protection Assay" confirmou essa expressão.

The length of cotton fiber is an important agronomic trait characteristic that directly affects the quality of yarn and fabric. The cotton (Gossypium hirsutum L.) fiber mutation, Ligon lintless-2, is controlled by a single dominant gene (Li 2 ) and results in extremely shortened lint fibers on mature seeds with no visible pleiotropic effects on vegetative growth and development. The Li 2 mutant phenotype provides an ideal model system to study fiber elongation. To understand metabolic processes involved in cotton fiber elongation, changes in metabolites and transcripts in the Li 2 mutant fibers were compared to wild-type fibers during development. Principal component analysis of metabolites from GC-MS data separated Li 2 mutant fiber samples from WT fiber samples at the WT elongation stage, indicating that the Li 2 mutation altered the metabolome of the mutant fibers. The observed alterations in the Li 2 metabolome included significant reductions in the levels of detected free sugars, sugar alcohols, sugar acids, and sugar phosphates. Biological processes associated with carbohydrate biosynthesis, cell wall loosening, and cytoskeleton were also down-regulated in Li 2 fibers. Gamma-aminobutyric acid, known as a signaling factor in many organisms, was significantly elevated in mutant fibers. Higher accumulation of 2-ketoglutarate, succinate, and malate suggested higher nitrate assimilation in the Li 2 line. Transcriptional activation of genes involved in nitrogen compound metabolism along with changes in the levels of nitrogen transport amino acids suggested re-direction of carbon flow into nitrogen metabolism in Li 2 mutant fibers. This report provides the first comprehensive analysis of metabolite and transcript changes in response to the Li 2 mutation in elongating fibers. A number of factors associated with cell elongation found in this study will facilitate further research in understanding metabolic processes of cotton fiber elongation.

Background Cotton fiber length is very important to the quality of textiles. Understanding the genetics and physiology of cotton fiber elongation can provide valuable tools to the cotton industry by targeting genes or other molecules responsible for fiber elongation. Ligon Lintless-1 (Li 1 ) is a monogenic mutant in Upland cotton (Gossypium hirsutum) which exhibits an early cessation of fiber elongation resulting in very short fibers (< 6 mm) at maturity. This presents an excellent model system for studying the underlying molecular and cellular processes involved with cotton fiber elongation. Previous reports have characterized Li 1 at early cell wall elongation and during later secondary cell wall synthesis, however there has been very limited analysis of the transition period between these developmental time points. Results Physical and morphological measurements of the Li 1 mutant fibers were conducted, including measurement of the cellulose content during development. Affymetrix microarrays were used to analyze transcript profiles at the critical developmental time points of 3 days post anthesis (DPA), the late elongation stage of 12 DPA and the early secondary cell wall synthesis stage of 16 DPA. The results indicated severe disruption to key hormonal and other pathways related to fiber development, especially pertaining to the transition stage from elongation to secondary cell wall synthesis. Gene Ontology enrichment analysis identified several key pathways at the transition stage that exhibited altered regulation. Genes involved in ethylene biosynthesis and primary cell wall rearrangement were affected, and a primary cell wall-related cellulose synthase was transcriptionally repressed. Linkage mapping using a population of 2,553 F2 individuals identified SSR markers associated with the Li 1 genetic locus on chromosome 22. Linkage mapping in combination with utilizing the diploid G. raimondii genome sequences permitted additional analysis of the region containing the Li 1 gene. Conclusions The early termination of fiber elongation in the Li 1 mutant is likely controlled by an early upstream regulatory factor resulting in the altered regulation of hundreds of downstream genes. Several elongation-related genes that exhibited altered expression profiles in the Li 1 mutant were identified. Molecular markers closely associated with the Li 1 locus were developed. Results presented here will lay the foundation for further investigation of the genetic and molecular mechanisms of fiber elongation.