Gossypium Barbadense Research Articles

Deciphering the fiber quality of Gossypium barbadense L. var. brasiliensis in La Convención, Cusco, Perú

BackgroundThe quality of cotton fiber determines its value in the textile market, influencing agricultural profitability and the efficiency of textile processing. The selection of genotypes with superior fibers is a key factor for genetic improvement programs seeking adaptability and sustainability in the face of climate change. This demonstrates the strategic importance of this plant for sustainable agriculture and the global textile industry. The objective of this research was to decipher the fiber quality of Gossypium barbadense var. brasiliensis in the native Amazonian communities of La Convención, Cusco-Perú, and to evaluate other critical aspects of native cotton that have not yet been identified. The methodology included non-probability sampling for accessibility, qualitative and quantitative analyses, and multivariate analyses. The fiber length (mm), micronaire index (maturity/fineness), fiber strength (gf/tex), length uniformity index (%), fiber elongation (%), maturation index (%), and short fiber index (%) were the fiber characteristics evaluated using the HVI method in cotton genotypes.ResultsCotton accessions collected from Koribeni (Gossypium spp.) and Shivankoreni (Gossypium barbadense var. brasiliensis) stood out for their fiber quality properties, especially length, strength, and uniformity, which highlights their relevance for advanced textile applications and potential for use in plant genetic improvement programs.ConclusionThese findings reinforce the need to conserve and study these native cotton accessions from the Peruvian Amazon region, which can offer promising perspectives for the textile industry and agricultural biodiversity.

Genome-Wide Identification of the WRKY Gene Family in Four Cotton Varieties and the Positive Role of GhWRKY31 in Response to Salt and Drought Stress.

The WRKY gene family is ubiquitously distributed in plants, serving crucial functions in stress responses. Nevertheless, the structural organization and evolutionary dynamics of WRKY genes in cotton have not been fully elucidated. In this study, a total of 112, 119, 217, and 222 WRKY genes were identified in Gossypium arboreum, Gossypium raimondii, Gossypium hirsutum, and Gossypium barbadense, respectively. These 670 WRKY genes were categorized into seven distinct subgroups and unequally distributed across chromosomes. Examination of conserved motifs, domains, cis-acting elements, and gene architecture collectively highlighted the evolutionary conservation and divergence within the WRKY gene family in cotton. Analysis of synteny and collinearity further confirmed instances of expansion, duplication, and loss events among WRKY genes during cotton evolution. Furthermore, GhWRKY31 transgenic Arabidopsis exhibited heightened germination rates and longer root lengths under drought and salt stress. Silencing GhWRKY31 in cotton led to reduced levels of ABA, proline, POD, and SOD, along with downregulated expression of stress-responsive genes. Yeast one-hybrid and molecular docking assays confirmed the binding capacity of GhWRKY31 to the W box of GhABF1, GhDREB2, and GhRD29. The findings collectively offer a systematic and comprehensive insight into the evolutionary patterns of cotton WRKYs, proposing a suitable regulatory framework for developing cotton cultivars with enhanced resilience to drought and salinity stress.

Biochemical and toxicological effects of certain bioinsecticides on The Egyptian cotton leafworm Spodoptera littoralis

Biochemical and toxicological effects of certain bioinsecticides on The Egyptian cotton leafworm Spodoptera littoralis

Insecticidal Activity of Allium sativum Essential Oil-Based Nanoemulsion against Spodoptera littoralis.

Spodoptera littoralis, commonly known as the Egyptian or African cotton leafworm, is a significant agricultural threat. It is widely distributed in Africa, Mediterranean Europe, and Middle Eastern countries. This polyphagous pest infests numerous crop plants across 44 families, including cotton, soybeans, alfalfa, sweet potato, pepper, eggplant, tomato, maize, lettuce, strawberry, wheat, and hibiscus. The damage caused by S. littoralis on different plant organs, such as young leaves, shoots, stalks, bolls, buds, and fruits, often determines substantial product losses. Current control strategies predominantly rely on synthetic insecticides, which, despite their efficacy, have notable drawbacks, including insecticide resistance, environmental contamination, consumer concerns, and adverse effects on non-target organisms and beneficial insects. In response to these challenges, in this study, we developed and evaluated a garlic EO-based nanoemulsion with a high EO concentration (15%) and low surfactant content to mitigate the possible negative impact on plants and to enhance efficacy against S. littoralis larvae. Laboratory bioassays demonstrated promising larvicidal activity and reduced larval feeding, although some phytotoxicity symptoms were observed. This study underscores the potential of botanical insecticides as sustainable alternatives to synthetic chemicals, emphasizing the importance of balancing efficacy with environmental and ecological considerations in pest management strategies.

GbPP2C80 Interacts with GbWAKL14 to Negatively Co-Regulate Resistance to Fusarium and Verticillium wilt via MPK3 and ROS Signaling in Sea Island Cotton.

Fusarium wilt (FW) is widespread in global cotton production, but the mechanism underlying FW resistance in superior-fiber-quality Sea Island cotton is unclear. This study reveals that FW resistance has been the target of genetic improvement of Sea Island cotton in China since the 2010s. The key nonsynonymous single nucleotide polymorphism (SNP, T/C) of gene Gbar_D03G001670 encoding protein phosphatase 2C 80 (PP2C80) results in an amino acid shift (L/S), which is significantly associated with FW resistance of Sea Island cotton. Silencing GbPP2C80 increases FW resistance in Sea Island cotton, whereas overexpressing GbPP2C80 reduces FW resistance in Arabidopsis. GbPP2C80 and GbWAKL14 exist synergistically in Sea Island cotton accessions with haplotype forms "susceptible-susceptible" (TA) and "resistant-resistant" (CC), and interact with each other. CRISPR/Cas9-mediated knockout of GbWAKL14 enhances FW and Verticillium wilt (VW) resistance in upland cotton and overexpression of GbWAKL14 and GbPP2C80 weakens FW and VW resistance in Arabidopsis. GbPP2C80 and GbWAKL14 respond to FW and VW by modulating reactive oxygen species (ROS) content via affecting MPK3 expression. In summary, two tandem genes on chromosome D03, GbPP2C80, and GbWAKL14, functions as cooperative negative regulators in cotton wilt disease defense, providing novel genetic resources and molecular markers for the development of resistant cotton cultivars.

Genome-wide identification of TBL gene family and functional analysis of GhTBL84 under cold stress in cotton.

Cotton fiber, the mainstay of the world's textile industry, is formed by the differentiation of epidermal cells on the outer peridium of the ovule. The TBL gene family is involved in the regulation of epidermal hair development as well as response to abiotic stress. However, the function of TBL genes in cotton has not been systematically studied yet. Here, we identified 131 and 130 TBL genes in TM-1 (Gossypium hirsutum) and Hai7124 (Gossypium barbadense), respectively. Phylogenetic, gene structure, expression pattern and cis-element of promoter analysis were performed and compared. Single gene association analysis indicated that more TBL genes related to fiber quality traits were found in G. barbadense, whereas more genes associated with yield traits were found in G. hirsutum. One gene, GhTBL84 (GH_D04G0930), was induced by treatment at 4°C for 12 and 24 h in G. hirsutum and silencing of the GhTBL84 gene by VIGS technology in TM-1 can significantly improve the resistance of cotton seedlings to low temperature stress. In sum, our study conducted a genome-wide identification and comparative analysis of TBL family genes in G. hirsutum and G. barbadense and demonstrated a group of TBL genes significantly associated with fiber quality and excavated cold stress responsive gene, such as GhTBL84, providing a theoretical basis for further improving cotton agronomic traits.

Comprehensive Genome-Wide Investigation and Transcriptional Regulation of the DHHC Gene Family in Cotton Seed and Fiber Development

Protein palmitoylation, the most common and the only reversible post-translational lipid modification following protein translation, plays a pivotal role in the biochemical and physiological processes of both animals and plants. DHHC proteins, enriched with DHHC (Asp-His-His-Cys) domains, serve as catalyst for protein palmitoylation. However, research on DHHC in cotton remains scarce. This study conducted a systematic characterization and bioinformatics analysis on G. arboreum, G. raimondii, G. hirsutum, and G. barbadense, detecting 38, 37, 74, and 74 DHHC genes, respectively. Phylogenetic analysis categorized the DHHC gene family into six subgroups, consistent with previous evolutionary studies in Arabidopsis and rice. A further examination of protein structure revealed a correlation between genetic relatedness, structural similarity, and functional identity. Cis-element analysis identified elements predominantly associated with light response, stress, growth and development, and plant hormones. The integration of cotton seed development transcriptome, tissue expression pattern analysis, and population transcriptome data collectively suggests that Ghir_A05G027650 and Ghir_D05G027670 are promising candidate genes influencing seed development in upland cotton. Conversely, Gbar_A04G010750 and Gbar_A12G020520 emerge as potential candidates affecting both seed and fiber development in sea island cotton. These findings lay down a theoretical foundation for delving into the functional diversity of DHHC genes in cotton, thereby paving the way for the development of new breeding strategies and the optimization of cotton seed and fiber production, ultimately contributing to improved crop yield and quality.

Grafting based DNA methylation alteration of snoRNAs in upland cotton (Gossypium L.)

The effects of grafting in response to various biotic and abiotic stressors have been studied, however, the methylation status of small nucleolar RNA (snoRNA) genes in heterograft and homograft cotton needs investigation. This study was undertaken to determine grafting effects on DNA methylation of snoRNA genes in Upland cotton. Rootstocks used were Pima 3–79 (Gossypium barbadense acc. Pima 3–79) and Texas Marker-1 (G. hirsutum acc. TM-1), representing two different species with different fiber properties, adaptations, and morphologies. The methylation ratio and differently methylated cytosines (DMCs) of 10935 snoRNA genes in mature seeds of heterograft and homograft cotton samples were studied using the whole genome bisulfite sequencing method. Seedling vigor and seed weight were studied to investigate phenotype alterations that might be associated with altered methylation levels among grafts. Statistically significant DMC differences among gene elements of snoRNA genes and between homograft and heterograft cotton samples were identified in the absence of DNA sequence alterations. DNA methylation alterations of snoRNA genes associated with seedling vigor and 100 seed weight. The majority of snoRNA genes showed higher numbers of mCG + mCHG-DMCs with increased methylation levels in heterograft, while there were higher numbers of mCG + mCHG-DMCs with decreased methylation levels in homograft. Since snoRNAs regulate essential genes for plant growth and development and plant adaptation to different habitats or extreme environments, their altered methylation levels should be related with plant physiology.

Evaluation of Cotton Cultivars and Breeding Lines for Tolerance to Monosodium Methanearsonate (MSMA) Under Field Conditions

Monosodium methanearsonate (MSMA) is an organic arsenical herbicide used to control weeds such as grasses and nutsedges in Upland cotton (Gossypium hirsutum) production. Transient crop injury, yield reduction, and maturity delays have been observed in commercial Upland cotton. It is unknown if genetic variation in MSMA tolerance in cotton exists. In this field study, seven replicated tests were conducted in the same field to compare MSMA tolerance among 212 commercial cotton cultivars and advanced breeding lines. The tests were sprayed over the top at the 4-true-leaf stage, and seedlings were assessed for crop injury severity on a scale of 0 (no injury) to 5 (death). Significant genotypic variation in MSMA tolerance was detected in three tests, and broad-sense heritability estimates for MSMA tolerance ranged from 0.476 to 0.846 with a mean of 0.712, indicating that most phenotypic variation in MSMA tolerance is heritable. Nine tested G. barbadense genotypes, including seven commercial Pima cultivars and two Sea-Island cotton lines, exhibited minimal crop injury with severity ratings of 0.40 to 0.83 (except for one cultivar with 1.33). Among the remaining 203 Upland cotton genotypes with crop injury ratings ranging from 0.90 to 3.67, five commercial transgenic cultivars and 38 public breeding lines exhibited various levels of MSMA tolerance. The results represent the first study in germplasm evaluation for MSMA tolerance and identify a set of tolerant cotton genotypes that can be selected in cotton production or used to develop new cultivars for commercial cotton production.

Genetic diversity in Pima (Gossypium barbadense L.) and advanced interspecific hybrids (Gossypium hirsutum x Gossypium barbadense) of cotton germplasm in Ethiopia

This study was conducted to assess the genetic diversity in Pima (Gossypium barbadense L.) and advanced interspecific hybrids (G. hirsutum L. x G. barbadense L.) of cotton germplasm in Ethiopia. A total of 26 germplasm were genotyped using 26 polymorphic simple sequence repeat (SSR) markers. A total of 165 polymorphic loci, with a range of 3 to 13 alleles and a mean of 6.35 per marker were detected. About 11% of total alleles were unique alleles in 11 germplasm. The gene diversity varied from 0.39 to 0. 89, while the heterozygosity was in the range of 0 to 1.00. Furthermore, the polymorphic information content of the markers varied from 0.37 (BNL1417) to 0.88 (BNL1672) with an average of 0.68. Among the complete panel of cotton germplasm used in this study, the pairwise genetic distance ranged from 0.08 to 0.94, with an overall mean of 0.61. The UPGMA cluster analysis grouped the Pima cotton germplasm into two cluster groups and the advanced interspecific hybrid cotton germplasm makes one cluster. Principal coordinate analysis indicates that the first three most informative principal coordinates explained 68.4% of the genetic variation. The result evidenced very low to high genetic dissimilarity and overall, a considerable genetic diversity among and within germplasm which could be used to further broaden the genetic base and to enlarge the number of available cotton germplasm.

Technological Characteristics of Some Egyptian Cotton Varieties as affected by Cultivation Regions

Technological Characteristics of Some Egyptian Cotton Varieties as affected by Cultivation Regions

GhVIM28, a negative regulator identified from VIM family genes, positively responds to salt stress in cotton

The VIM (belonged to E3 ubiquitin ligase) gene family is crucial for plant growth, development, and stress responses, yet their role in salt stress remains unclear. We analyzed phylogenetic relationships, chromosomal localization, conserved motifs, gene structure, cis-acting elements, and gene expression patterns of the VIM gene family in four cotton varieties. Our findings reveal 29, 29, 17, and 14 members in Gossypium hirsutum (G.hirsutum), Gossypium barbadense (G.barbadense), Gossypium arboreum (G.arboreum), and Gossypium raimondii (G. raimondii), respectively, indicating the maturity and evolution of this gene family. motifs among GhVIMs genes were observed, along with the presence of stress-responsive, hormone-responsive, and growth-related elements in their promoter regions. Gene expression analysis showed varying patterns and tissue specificity of GhVIMs genes under abiotic stress. Silencing GhVIM28 via virus-induced gene silencing revealed its role as a salt-tolerant negative regulator. This work reveals a mechanism by which the VIM gene family in response to salt stress in cotton, identifying a potential negative regulator, GhVIM28, which could be targeted for enhancing salt tolerance in cotton. The objective of this study was to explore the evolutionary relationship of the VIM gene family and its potential function in salt stress tolerance, and provide important genetic resources for salt tolerance breeding of cotton.

Comparative analysis of key fiber characteristics in white Pima cotton (Gossypium barbadense L.): Native accessions from the Peruvian Amazon

AbstractThe fiber quality of cotton (Gossypium barbadense L.) native to the Peruvian Amazon region is one of the most versatile and essential natural fibers in the Peruvian textile industry. There is little information about the fiber quality traits of cotton genotypes native to the Peruvian Amazon region. This study investigated the fiber quality traits of Peruvian Pima cotton accessions native to the Amazon region of the La Convención Province, Cusco, Peru, to determine the lines with the greatest potential for improving fiber quality in cotton genetic breeding programs. A total of 14 cotton accessions with white fiber color, being 12 accessions of G. barbadense L. (Pima cotton) and two accessions of Gossypium sp. (unknown cotton), were analyzed. The fiber properties determined using the high volume instrument method included seven characteristics. All fiber properties were classified into five quality classes. The data on fiber quality properties were subjected to distribution, correlation, and canonical variable analysis. The results of fiber quality properties showed that the two accessions of Gossypium sp. (unknown cotton) can be promising options to be used as high‐quality fiber progenies in crop genetic breeding programs or can be cultivated by regional farmers for the purpose of producing cotton with high fiber quality. Future investigations could utilize other methods of fiber quality analysis and compare the fiber quality of these cotton accessions native to the Peruvian Amazon region with other cotton species grown worldwide to improve the understanding of Pima cotton fiber quality and its applicability in different contexts of the textile industries.

Integrative transcriptomic and metabolomic analysis revealed the molecular mechanisms of fiber length difference between the micropylar end and chalazal end of ovule in interspecific hybrid cotton (Gossypium hirsutum × Gossypium barbadense)

Cotton fiber is an indispensable raw material in the textile industry. Fiber length is an important fiber quality index, and the research on fiber length is also quite abundant. However, on the same ovule, there are only a few studies on the difference in fiber length development between the micropylar end and the chalazal end of the ovule. We elucidate the mechanism of fiber length differences at both ends of the ovule through the phenomics, transcriptome, and metabolome. The results show that 20, 25, and 30 days post anthesis (DPA) are the pivotal stages to causing the difference in fiber length at two ends of the ovules. Through the KEGG annotation of differentially expressed genes (DEGs), it was found that flavonoid biosynthesis, plant hormone signal transduction, and phenylpropanoid biosynthesis are enriched in DEGs, and similar conclusions were drawn in the analysis of differential abundant metabolites (DAMs). The results of in vitro culture of ovules showed that chlorogenic acid in the flavonoid pathway and scopolin downstream of the phenylpropanoid pathway have significant effects on fiber growth. Our research provide insights into the mechanism of cotton fiber elongation.

Exploring agro-morphological and fiber traits diversity in cotton (G. barbadense L.)

Cotton (Gossypium barbadense L.) is a leading fiber and oilseed crop globally, but genetic diversity among breeding materials is often limited. This study analyzed genetic variability in 14 cotton genotypes from Egypt and other countries, including both cultivated varieties and wild types, using agro-morphological traits and genomic SSR markers. Field experiments were conducted over two seasons to evaluate 12 key traits related to plant growth, yield components, and fiber quality. Molecular diversity analysis utilized 10 SSR primers to generate DNA profiles. The Molecular diversity analysis utilized 10 SSR primers to generate DNA profiles. Data showed wide variation for the morphological traits, with Egyptian genotypes generally exhibiting higher means for vegetative growth and yield parameters. The top-performing genotypes for yield were Giza 96, Giza 94, and Big Black Boll genotypes, while Giza 96, Giza 92, and Giza 70 ranked highest for fiber length, strength, and fineness. In contrast, molecular profiles were highly polymorphic across all genotypes, including 82.5% polymorphic bands out of 212. Polymorphism information content was high for the SSR markers, ranging from 0.76 to 0.86. Genetic similarity coefficients based on the SSR data varied extensively from 0.58 to 0.91, and cluster analysis separated genotypes into two major groups according to geographical origin. The cotton genotypes displayed high diversity in morphology and genetics, indicating sufficient variability in the germplasm. The combined use of physical traits and molecular markers gave a thorough understanding of the genetic diversity and relationships between Egyptian and global cotton varieties. The SSR markers effectively profiled the genotypes and can help select ideal parents for enhancing cotton through hybridization and marker-assisted breeding.

Genome-wide expression analysis of LACS gene family implies GhLACS25 functional responding to salt stress in cotton

BackgroundLong-chain acyl-coenzyme A synthetase (LACS) is a type of acylating enzyme with AMP-binding, playing an important role in the growth, development, and stress response processes of plants.ResultsThe research team identified different numbers of LACS in four cotton species (Gossypium hirsutum, Gossypium barbadense, Gossypium raimondii, and Gossypium arboreum). By analyzing the structure and evolutionary characteristics of the LACS, the GhLACS were divided into six subgroups, and a chromosome distribution map of the family members was drawn, providing a basis for further research classification and positioning. Promoter cis-acting element analysis showed that most GhLACS contain plant hormones (GA, MeJA) or non-biological stress-related cis-elements. The expression patterns of GhLACS under salt stress treatment were analyzed, and the results showed that GhLACS may significantly participate in salt stress response through different mechanisms. The research team selected 12 GhLACSs responsive to salt stress for tissue expression analysis and found that these genes are expressed in different tissues.ConclusionsThere is a certain diversity of LACS among different cotton species. Analysis of promoter cis-acting elements suggests that GhLACS may be involved in regulating plant growth, development and stress response processes. GhLACS25 was selected for in-depth study, which confirmed its significant role in salt stress response through virus-induced gene silencing (VIGS) and induced expression in yeast cells.

Unraveling the genetic basis of superior traits in Gossypium barbadense: From phenotype to genotype

G. barbadense is renowned for its high-quality fiber and is highly regarded as a natural material in the textile industry. However, research on cotton has mainly focused on G. hirsutum, and progress in sea island cotton has been relatively slow. There was limited understanding of the genetic loci and transcriptional regulatory mechanisms of important traits, and the genetic basis for the development of superior traits remains unclear. In this study, a recombinant inbred line (RIL) population was constructed using two sea island cotton parents from different cotton regions. The phenotypic characteristics of the two parents and the RIL population, as well as the phenotypic correlations, heritability, and genetic models of the RIL population, were comprehensively analyzed. The RIL population was genotyped using whole-genome resequencing technology, and a high-density intraspecific linkage map was constructed, consisting of 5295 bin markers and a total genetic map distance of 2721.79 centimorgans (cM). Phenotypic data collected from five different environments were used to detect 169 quantitative trait loci (QTLs) using the composite interval mapping method. Among these QTLs, 30 were related to agronomic traits, 61 were related to yield traits, and 78 were related to fiber quality traits. Additionally, 17 QTL clusters were detected, and the additive effects of these clusters explained the correlation between different phenotypic traits. Candidate genes for stable QTLs related to agronomic and yield traits were identified through variant annotation and functional prediction. Two bin markers associated with lint percentage (LP) were validated as potential breeding markers. Furthermore, using RNA-seq data of cotton fiber from the RIL population parents, the dynamic changes in gene expression during different developmental stages of cotton fiber were revealed, and important differentially expressed genes in the secondary cell wall development and metabolism network of fibers were identified. Importantly, through the combined analysis of fiber trait QTLs and transcriptomes, eight candidate genes involved in regulating fiber quality traits were predicted, and the genetic basis of the excellent allele site qFL_D04_1 in the breeding history of Chinese sea island cotton was elucidated. In summary, this study provides new genetic resources and potential breeding markers for cotton variety improvement, valuable theoretical information for understanding the genetic basis of important traits in sea island cotton, and effectively promotes the development of cotton biotechnology breeding.

Fabrication and characterization of microemulsion of some insecticides and evaluating their efficacy against cotton leaf worm on cotton crop under laboratory and field conditions

AbstractTraditional pesticide formulations have some shortcomings, including limited efficacy and the usage of huge amounts of insecticide, which has a negative impact on the environment. Using nano‐pesticide formulations reduces the amount of pesticide applied, minimizing pest control expenses and environmental contamination. As a result, this study was conducted to develop a microemulsion formulation containing emamectin benzoate or beta‐cyfluthrin with improved morphology, droplet size, emulsion stability, and persistence of foam. Moreover to assess the efficacy of the developed microemulsion in comparison to the convention alone against the Egyptian cotton leaf worm, Spodoptera littoralis (Boisd.) under both laboratory and field conditions. The results showed that the optimum conditions for emamectin benzoate microemulsion was 2% active ingredient, 5% (w/w) ethyl acetate, and DMF (3:2), 3.5% (w/w) Geronol ff4 and Etocas 35 (6:1), 5% (w/w) ethanol, and 86.5% (w/w) water, while for beta‐cyfluthrin, a 5.0% active ingredient, 15% (w/w) Solvesso 100 and ethyl acetate (2:1), 7.0% (w/w) Geronol ff4 and Etocas 35 (6:1), 10% (w/w) ethanol, and 68% (w/w) water. Under laboratory conditions, emamectin benzoate was more toxic than beta‐cyfluthrin to Spodoptera littoralis second and fourth instar larvae. Emamectin benzoate was more effective that beta‐cyfluthrin against Spodoptera littoralis in the field, whether as a microemulsion or a commercial product. Thus, microemulsions of tested insecticides with better formulation qualities may be more effective than traditional ones in controlling cotton leaf worm.

Fate of synthetic chemicals in the agronomic insect pest Spodoptera littoralis: experimental feeding-contact assay and toxicokinetic model.

Insecticides prevent or reduce insect crop damage, maintaining crop quality and quantity. Physiological traits, such as an insect's feeding behavior, influence the way insecticides are absorbed and processed in the body (toxicokinetics), which can be exploited to improve species selectivity. To fully understand the uptake of insecticides, it is essential to study their total uptake and toxicokinetics independent of their toxic effects on insects. We studied the toxicokinetics (TK) of insecticidally inactive test compounds incorporating agro-like structural motifs in larvae of the Egyptian cotton leafworm (Spodoptera littoralis,Lepidoptera),and their distribution across all biological matrices, using laboratory experiments and modeling. We measured Spodoptera larval behavior and temporal changes of whole-body concentrations of test compounds during feeding on treated soybean leaf disks and throughout a subsequent depuration period. Differences in the distribution of the total quantities of compounds were found between the biological matrices leaf, larva, and feces. Rate constants for uptake and elimination of test compounds were derived by calibrating a toxicokinetic model to the whole-body concentrations. Uptake and elimination rate constants depended on the physicochemical properties of the test compounds. Increasing hydrophobicity increased the bioaccumulation potential of test compounds. Incomplete quantities in larval matrices indicated that some compounds may undergo biotransformation. As fecal excretion was a major elimination pathway, the variable time of release and number of feces pellets led to a high variability in the body burden. We provide quantitative models to predict the toxicokinetics and bioaccumulation potential of inactive insecticide analogs (parent compounds) in Spodoptera.

Fine mapping and targeted genomic analyses of photoperiod‐sensitive gene (GB_PPD1) in Pima cotton (Gossypium barbadense L.)

AbstractCotton grown in the United States are day‐length insensitive annuals and are grown under long‐day summers. Photoperiod sensitivity, present in tropical wild and landraces endemic to the center of origin and diversity, is a major barrier for the introgression of tropical gene pool into the US cotton. Previously, we mapped the major photoperiod response locus Gb_Ppd1 on chromosome D06 of Pima cotton (Gossypium barbadense L.). In the current study, an F2 population of 2112 gametes was used to fine map the Gb_Ppd1 locus. Two sequence‐tagged‐site and nine kompetitive allele‐specific polymerase chain reaction (KASP) markers were developed and the Gb_Ppd1 locus was fine mapped to 1.1 cM region flanked by novel markers 17‐KASP‐8, 17‐KASP‐10, and 15‐PR‐10A. The closely linked markers identified 2.10 Mb region in the G. barbadense genome that contained 18 putative gene sequences. A candidate gene Gbar_D06G014560 showed high homology to VASCULAR PLANT ONE ZINC FINGER PROTEIN 1 involved in photoperiodism in Arabidopsis. We evaluated the diagnostic polymorphisms for the flanking markers on a diversity panel of 91 Pima accessions. These markers would be useful in marker‐assisted selection of photoperiod response in cotton breeding. Further, quantitative gene expression analysis indicated that the CONSTANS (CO)/FLOWERING LOCUS T (FT) system is conserved in the photoperiod response pathway in Pima cotton, while CO and FT are likely not the causal genes underlying flowering time at the Gb_Ppd1 locus. The Gb_Ppd1 gene may be an upstream regulatory sequence in the FT gene pathway that controls photoperiodism in photoperiod‐sensitive cotton by affecting the CO/FT interaction under long‐day‐length conditions.