Genes In Cotton Research Articles

Evolution and Characterization of Acetyl Coenzyme A: Diacylglycerol Acyltransferase Genes in Cotton Identify the Roles of GhDGAT3D in Oil Biosynthesis and Fatty Acid Composition

Cottonseed oil is rich in unsaturated fatty acids (UFAs) and serves as an edible oil in human nutrition. Reports suggest that acyl-coenzyme A: diacylglycerol acyltransferases (DGAT) and wax ester synthase/DGAT (WSD1) genes encode a key group of enzymes that catalyze the final step for triacylglycerol biosynthesis and enable an important rate-limiting process. However, their roles in oil biosynthesis and the fatty acid profile of cotton seed are poorly understood. Therefore, the aim of this study was to identify and characterize DGAT and WSD1 genes in cotton plants and examine their roles in oil biosynthesis, the fatty acid profile of cotton seeds, and abiotic stress responses. In this study, 36 GhDGAT and GhWSD1 genes were identified in upland cotton (G. hirsutum) and found to be clustered into four groups: GhDGAT1, GhDGAT2, GhDGAT3, and GhWSD1. Gene structure and domain analyses showed that the GhDGAT and GhWSD1 genes in each group are highly conserved. Gene synteny analysis indicated that segmental and tandem duplication events occurred frequently during cotton evolution. Expression analysis revealed that GhDGAT and GhWSD1 genes function widely in cotton development and stress responses; moreover, several environmental stress and hormone response-related cis-elements were detected in the GhDGAT and GhWSD1 promoter regions. The predicted target transcription factors and miRNAs imply an extensive role of GhDGAT and GhWSD1 genes in stress responses. Increases in GhDGAT3 gene expression with increases in cottonseed oil accumulation were observed. Transformation study results showed that there was an increase in C18:1 content and a decrease in C18:2 and C18:3 contents in seeds of Arabidopsis transgenic plants overexpressing GhDGAT3D compared with that of control plants. Overall, these findings contributed to the understanding of the functions of GhDGAT and GhWSD1 genes in upland cotton, providing basic information for further research.

Genome-Wide Identification of the Early Flowering 4 (ELF4) Gene Family in Cotton and Silent GhELF4-1 and GhEFL3-6 Decreased Cotton Stress Resistance.

The early flowering 4 (ELF4) family members play multiple roles in the physiological development of plants. ELF4s participated in the plant biological clock’s regulation process, photoperiod, hypocotyl elongation, and flowering time. However, the function in the ELF4s gene is barely known. In this study, 11, 12, 21, and 22 ELF4 genes were identified from the genomes of Gossypium arboreum, Gossypium raimondii, Gossypium hirsutum, and Gossypium barbadense, respectively. There ELF4s genes were classified into four subfamilies, and members from the same subfamily show relatively conservative gene structures. The results of gene chromosome location and gene duplication revealed that segmental duplication promotes gene expansion, and the Ka/Ks indicated that the ELF4 gene family has undergone purification selection during long-term evolution. Spatio-temporal expression patterns and qRT-PCR showed that GhELF4 genes were mainly related to flower, leaf, and fiber development. Cis-acting elements analysis and qRT-PCR showed that GhELF4 genes might be involved in the regulation of abscisic acid (ABA) or light pathways. Silencing of GhELF4-1 and GhEFL3-6 significantly affected the height of cotton seedlings and reduced the resistance of cotton. The identification and functional analysis of ELF4 genes in upland cotton provide more candidate genes for genetic modification.

Melatonin Improves Cotton Salt Tolerance by Regulating ROS Scavenging System and Ca2 + Signal Transduction.

As one of the cash crops, cotton is facing the threat of abiotic stress during its growth and development. It has been reported that melatonin is involved in plant defense against salt stress, but whether melatonin can improve cotton salt tolerance and its molecular mechanism remain unclear. We investigated the role of melatonin in cotton salt tolerance by silencing melatonin synthesis gene and exogenous melatonin application in upland cotton. In this study, applicating of melatonin can improve salt tolerance of cotton seedlings. The content of endogenous melatonin was different in cotton varieties with different salt tolerance. The inhibition of melatonin biosynthesis related genes and endogenous melatonin content in cotton resulted in the decrease of antioxidant enzyme activity, Ca2+ content and salt tolerance of cotton. To explore the protective mechanism of exogenous melatonin against salt stress by RNA-seq analysis. Melatonin played an important role in the resistance of cotton to salt stress, improved the salt tolerance of cotton by regulating antioxidant enzymes, transcription factors, plant hormones, signal molecules and Ca2+ signal transduction. This study proposed a regulatory network for melatonin to regulate cotton’s response to salt stress, which provided a theoretical basis for improving cotton’s salt tolerance.

Genetic analysis for seed cotton yield and its contributing traits in interspecific crosses of diploid cotton (G. herbaceum × G. arboreum)

Generation mean study was carried out in two interspecific crosses of diploid cotton i.e., GBhv-302 × PA-812 and GBhv-302 × ARBa-1502 using six parameter model. Simple scaling tests along with joint scaling test were carried out to check the sufficiency of additive-dominance model. The estimates of dominant (h) gene action were higher than the additive (d) gene action in one or more characters studied. Among epistasis, additive × additive (i) type of gene action was found to be significant in cross GBhv-302 × PA-812 for sympodia per plant and ginning outturn and in cross GBhv-302 × ARBa-1502 for sympodia per plant, bolls per plant and seed cotton yield per plant. While dominance × dominance (l) type of gene effect contributed significantly in cross GBhv-302 × PA-812 for sympodia per plant and in cross GBhv-302 × ARBa-1502 for sympodia per plant, average boll weight, bolls per plant, average boll weight and seed cotton yield per plant. Duplicate type of epistasis was observed for sympodia per plant in both the crosses, for bolls per plant and seed cotton yield per plant in cross GBhv-302 × ARBa-1502 and for ginning outturn in cross GBhv-302 × PA-812. While complementary type of gene interaction was detected for bolls per plant and seed cotton yield per plant in cross GBhv-302 × PA-812 and for average boll weight and ginning outturn in cross GBhv-302 × ARBa-1502. Key words Diploid cotton, additive, dominance and epistasis gene actions

Comprehensive identification and expression analysis of B-Box genes in cotton

BackgroundB-BOX (BBX) proteins are zinc-finger transcription factors with one or two BBX domains and sometimes a CCT domain. These proteins play an essential role in regulating plant growth and development, as well as in resisting abiotic stress. So far, the BBX gene family has been widely studied in other crops. However, no one has systematically studied the BBX gene in cotton.ResultsIn the present study, 17, 18, 37 and 33 BBX genes were detected in Gossypium arboreum, G. raimondii, G. hirsutum and G. barbadense, respectively, via genome-wide identification. Phylogenetic analysis showed that all BBX genes were divided into 5 main categories. The protein motifs and exon/intron structures showed that each group of BBX genes was highly conserved. Collinearity analysis revealed that the amplification of BBX gene family in Gossypium spp. was mainly through segmental replication. Nonsynonymous (Ka)/ synonymous (Ks) substitution ratios indicated that the BBX gene family had undergone purification selection throughout the long-term natural selection process. Moreover, transcriptomic data showed that some GhBBX genes were highly expressed in floral organs. The qRT-PCR results showed that there were significant differences in GhBBX genes in leaves and shoot apexes between early-maturing materials and late-maturing materials at most periods. Yeast two-hybrid results showed that GhBBX5/GhBBX23 and GhBBX8/GhBBX26 might interact with GhFT. Transcriptome data analysis and qRT-PCR verification showed that different GhBBX genes had different biological functions in abiotic stress and phytohormone response.ConclusionsOur comprehensive analysis of BBX in G. hirsutum provided a basis for further study on the molecular role of GhBBXs in regulating flowering and cotton resistance to abiotic stress.

Molecular Traits and Functional Analysis of the CLAVATA3/Endosperm Surrounding Region-Related Small Signaling Peptides in Three Species of Gossypium Genus.

The CLAVATA3/endosperm surrounding region-related (CLE) small peptides are a group of C-terminally encoded and post-translationally modified signal molecules involved in regulating the growth and development of various plants. However, the function and evolution of these peptides have so far remained elusive in cotton. In this study, 55, 56, and 86 CLE genes were identified in the Gossypium raimondii, Gossypium arboreum, and Gossypium hirsutum genomes, respectively, and all members were divided into seven groups. These groups were distinctly different in their protein characteristics, gene structures, conserved motifs, and multiple sequence alignment. Whole genome or segmental duplications played a significant role in the expansion of the CLE family in cotton, and experienced purifying selection during the long evolutionary process in cotton. Cis-acting regulatory elements and transcript profiling revealed that the CLE genes of cotton exist in different tissues, developmental stages, and respond to abiotic stresses. Protein properties, structure prediction, protein interaction network prediction of GhCLE2, GhCLE33.2, and GhCLE28.1 peptides were, respectively, analyzed. In addition, the overexpression of GhCLE2, GhCLE33.2, or GhCLE28.1 in Arabidopsis, respectively, resulted in a distinctive shrub-like dwarf plant, slightly purple leaves, large rosettes with large malformed leaves, and lack of reproductive growth. This study provides important insights into the evolution of cotton CLEs and delineates the functional conservatism and divergence of CLE genes in the growth and development of cotton.

Cotton D genome assemblies built with long-read data unveil mechanisms of centromere evolution and stress tolerance divergence

BackgroundMany of genome features which could help unravel the often complex post-speciation evolution of closely related species are obscured because of their location in chromosomal regions difficult to accurately characterize using standard genome analysis methods, including centromeres and repeat regions.ResultsHere, we analyze the genome evolution and diversification of two recently diverged sister cotton species based on nanopore long-read sequence assemblies and Hi-C 3D genome data. Although D genomes are conserved in gene content, they have diversified in gene order, gene structure, gene family diversification, 3D chromatin structure, long-range regulation, and stress-related traits. Inversions predominate among D genome rearrangements. Our results support roles for 5mC and 6mA in gene activation, and 3D chromatin analysis showed that diversification in proximal-vs-distal regulatory-region interactions shape the regulation of defense-related-gene expression. Using a newly developed method, we accurately positioned cotton centromeres and found that these regions have undergone obviously more rapid evolution relative to chromosome arms. We also discovered a cotton-specific LTR class that clarifies evolutionary trajectories among diverse cotton species and identified genetic networks underlying the Verticillium tolerance of Gossypium thurberi (e.g., SA signaling) and salt-stress tolerance of Gossypium davidsonii (e.g., ethylene biosynthesis). Finally, overexpression of G. thurberi genes in upland cotton demonstrated how wild cottons can be exploited for crop improvement.ConclusionsOur study substantially deepens understanding about how centromeres have developed and evolutionarily impacted the divergence among closely related cotton species and reveals genes and 3D genome structures which can guide basic investigations and applied efforts to improve crops.

Genomic insight into the divergence and adaptive potential of a forgotten landrace G. hirsutum L. purpurascens

Wild progenitors are an excellent source for strengthening the genetic basis and accumulation of desirable variation lost because of directional selection and adaptation in modern cultivars. Here, we re-evaluate a landrace of Gossypium hirsutum, formerly known as Gossypium purpurascens. Our study seeks to understand the genomic structure, variation, and breeding potential of this landrace, providing potential insights into the biogeographic history and genomic changes likely associated with domestication. A core set of accessions, including current varieties, obsolete accessions, G. purpurascens, and other geographical landraces, are subjected to genotyping along with multilocation phenotyping. Population fixation statistics suggests a marked differentiation between G. purpurascens and three other groups, emphasizing the divergent genomic behavior of G. purpurascens. Phylogenetic analysis establishes the primitive nature of G. purpurascens, identifying it as a vital source of functional variation, the inclusion of which in the upland cotton (cultivated G. hirsutum) gene pool may broaden the genetic basis of modern cultivars. Genome-wide association results indicate multiple loci associated with domestication regions corresponding to flowering and fiber quality. Moreover, the conserved nature of G. purpurascens can also provide insights into the evolutionary process of G. hirsutum.

Genome-Wide Analysis of DA1-Like Genes in Gossypium and Functional Characterization of GhDA1-1A Controlling Seed Size.

Cotton (Gossypium spp.) is an economically important crop grown for natural fiber and seed oil production. DA1 is a ubiquitin receptor that determines final seed and organ size by restricting the period of cell proliferation. In the present study, we identified 7 DA1-like genes each in cultivated tetraploid (AADD) G. hirsutum and G. barbadense, and 4 and 3 DA1-like genes in their ancestral diploid G. arboreum (A2A2) and G. raimondii (D5D5), respectively. The 7 GhDA1 genes were confirmed to be distributed on four At and three Dt subgenome chromosomes in G. hirsutum. GhDA1-1A showed a high sequence similarity to AtDA1 in Arabidopsis, and they possessed the same functional domains, suggesting conserved functions. The overexpression of GhDA1-1AR301K in Arabidopsis significantly increased seed size and seed weight, indicating that GhDA1-1A is a promising target for cotton improvement. This study provides information on the molecular evolutionary properties of DA1-like genes in cotton, which will be useful for the genetic improvement of cotton.

Cotton DMP gene family: characterization, evolution, and expression profiles during development and stress

Members of DOMAIN OF UNKNOWN FUNCTION 679 membrane protein (DMP) gene family, a type of plant-specific membrane proteins, have been proposed to function in various physiological processes such as reproductive development and senescence in plants. Here, a total of 174 DMP genes were identified and analyzed in 16 plant species (including 58 DMPs in four cotton species). Phylogenetic analysis showed that these DMPs could be clustered into five subfamilies (I-V). 137 duplicated cotton gene pairs were identified and most duplicate events were formed by whole-genome duplication (WGD)/segmental duplications. Expression analysis revealed that most of cotton DMPs were mainly expressed in the reproductive organs (the sepal, petal, pistil and anther) and the fiber of secondary cell wall stage. GhDMPs promoter regions containing the different cis-elements also showed different responses to abiotic stress. In addition, gene interaction networks showed that DMPs, as an endomembrane system, were involved in plant senescence process and flower reproductive development. We speculated GhDMP8-A/-D, GbDMP8-A/-D could be used as some candidate gene for inducing cotton haploid. This genome-wide study provides a systematic analysis of the cotton DMP gene family, and further insights towards understanding the potential functions of candidate genes.

Electric field generated by high-voltage transmission system is beneficial to cotton growth

With the increasing popularity of high-voltage transmission systems, the potential effects of environmental electric fields (EFs) generated by these systems to surrounding organisms is gradually becoming a source of public concern. Cotton is planted on a large scale all over the world and is exposed inevitably to environmental EF. In this study, cotton was exposed continuously to power frequency electric field (PF EF) of different intensities (0 kV/m, 2 kV/m, and 10 kV/m) and evaluated on agronomic traits, yield, organic matter contents, protective enzyme activities, and genes expression over time and at different stages of plant growth. We found that cotton was impressionable by EF at the seedling stage, while it was relatively insensitive at the maturity stage. Exposure to PF EF is safe and beneficial to growth and yield for cotton in our experiment. Data collected from growing cotton of plant height, functional leaf number, dry weight of plant and boll, contents of soluble sugar and total protein, and activities of superoxide dismutase and catalase exhibited a tendency to increase under the EF treatment. Transcriptional analyses showed that EF caused significant changes in the expression levels of 86 genes of cotton, and most of which were up-regulated. These differentially expressed genes are involved in carbohydrate metabolic process and various transfer proteins synthesis, and are associated with the activity of some transferases and hydrolases, providing a novel perspective for understanding molecular mechanisms underpinning the yield increase of EF to cotton.

Population structure and genetic diversity of the Pee Dee cotton breeding program.

Accelerated marker-assisted selection and genomic selection breeding systems require genotyping data to select the best parents for combining beneficial traits. Since 1935, the Pee Dee (PD) cotton germplasm enhancement program has developed an important genetic resource for upland cotton (Gossypium hirsutum L.), contributing alleles for improved fiber quality, agronomic performance, and genetic diversity. To date, a detailed genetic survey of the program's eight historical breeding cycles has yet to be undertaken. The objectives of this study were to evaluate genetic diversity across and within-breeding groups, examine population structure, and contextualize these findings relative to the global upland cotton gene pool. The CottonSNP63K array was used to identify 17,441 polymorphic markers in a panel of 114 diverse PD genotypes. A subset of 4597 markers was selected to decrease marker density bias. Identity-by-state pairwise distance varied substantially, ranging from 0.55 to 0.97. Pedigree-based estimates of relatedness were not very predictive of observed genetic similarities. Few rare alleles were present, with 99.1% of SNP alleles appearing within the first four breeding cycles. Population structure analysis with principal component analysis, discriminant analysis of principal components, fastSTRUCTURE, and a phylogenetic approach revealed an admixed population with moderate substructure. A small core collection (n < 20) captured 99% of the program's allelic diversity. Allele frequency analysis indicated potential selection signatures associated with stress resistance and fiber cell growth. The results of this study will steer future utilization of the program's germplasm resources and aid in combining program-specific beneficial alleles and maintaining genetic diversity.

Silencing GhFAR3.1 reduces wax accumulation in cotton leaves and leads to increased susceptibility to drought stress.

Fatty acyl‐CoA reductases (FAR) are involved in plant wax synthesis and play important roles in plant growth and development. However, little information is available for cotton FAR genes. In this study, we carried out a genome‐wide identification of FAR genes in Upland cotton (Gossypium hirsutum L.) and found 10 GhFARs that form five pairs of homoeologs (GhFAR2A to GhFAR3.4D) distributed on six chromosomes. The 10 GhFARs were separated into two subfamilies. Most GhFARs showed tissue‐specific expression patterns, and at least one GhFAR of each pair of homoeologs was relatively highly expressed in at least one of the tissues investigated. GhFAR3.1 was highly expressed in leaves. The function of GhFAR3.1 in wax accumulation and drought tolerance was analyzed using virus‐induced gene silencing (VIGS). Silencing GhFAR3.1 reduced the total wax content and relative water content of leaves by over 60% and 13%, respectively, suggesting a role of GhFAR3.1 in wax synthesis and protection against water loss. Compared to the well‐watered conditions, drought stress induced significant accumulation of wax in leaves of wild‐type plants but not in leaves of GhFAR3.1 silenced plants, leading to less water holding capacity in GhFAR3.1 silenced plants and plant wilting. Silencing GhFAR3.1 had no effect on the expression levels of the wax biosynthesis pathway genes KAS, KCS, and LACS (upstream GhFAR3.1), but reduced the transcript level of its downstream gene WSD. Together, these results suggest that leaf wax content is important for water retention and drought tolerance and that GhFAR3.1 is essential for wax synthesis in cotton leaves. These results also provide the basis for further study on the molecular regulation mechanism of GhFARs in cotton development and surface lipid synthesis.

Identification, characterization, and expression profiles of the GASA genes in cotton

BackgroundGASA (Giberellic Acid Stimulated in Arabidopsis) gene family plays a crucial role in the phytohormone signaling pathway, growth and development, and stress responses in plants. Many GASA homologs have been identified in various plants. Nevertheless, little is known about these proteins in cotton.ResultsIn the current study, we identified 19, 17, 25, 33, and 38 GASA genes via genome-wide analyses of Gossypium herbaceum, G. arboreum, G. raimondii, G. barbadense, and G. hirsutum, respectively, and performed comprehensive bioinformatics and expression analyses. According to our results, 132 GASA proteins shared similar protein structures and were classified into four groups based on the phylogenetic tree. A synteny analysis suggested that segmental duplication was a key driver in the expansion of the GASA gene family. Meanwhile, the cis-element and protein interaction analyses indicated that GhGASA proteins play a significant role in the hormone responses. Transcriptomic and qRT-PCR (Quantitative real time-polymerase chain reaction) analyses revealed diverse expression profiles of the GhGASA genes in different organs under abiotic stresses, indicating that some GhGASA genes possibly participate in fiber development and abiotic-stress responses.ConclusionsThe GASA genes in cotton were systematically identified and analyzed for the first time in this paper, and it suggested that the GASA genes are important to the development and growth of cotton. These results will support future exploration of the functions of GASA genes in cotton.

Cotton transcriptome analysis reveals novel biological pathways that eliminate reactive oxygen species (ROS) under sodium bicarbonate (NaHCO3) alkaline stress

Alkaline stress is one of the abiotic stresses limiting cotton production. Though RNA-Seq analyses, have been conducted to investigate genome-wide gene expression in response to alkaline stress in plants, the response of sodium bicarbonate (NaHCO3) stress-related genes in cotton has not been reported. To explore the mechanisms of cotton response to this alkaline stress, we used next-generation sequencing (NGS) technology to study transcriptional changes of cotton under NaHCO3 alkaline stress. A total of 18,230 and 11,177 differentially expressed genes (DEGs) were identified in cotton roots and leaves, respectively. Gene ontology (GO) analysis indicated the enrichment of DEGs involved in various stimuli or stress responses. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis showed that DEGs associated with plant hormone signal transduction, amino acid biosynthesis, and biosynthesis of secondary metabolites were regulated in response to the NaHCO3 stress. We further analyzed genes enriched in secondary metabolic pathways and found that secondary metabolites were regulated to eliminate the reactive oxygen species (ROS) and improve the cotton tolerance to the NaHCO3 stress. In this study, we learned that the toxic effect of NaHCO3 was more profound than that of NaOH at the same pH. Thus, Na+, HCO3− and pH had a great impact on the growth of cotton plant. The novel biological pathways and candidate genes for the cotton tolerance to NaHCO3 stress identified from the study would be useful in the genetic improvement of the alkaline tolerance in cotton.

Seed morphology and cytogenetic characterization of an endangered wild cotton, Gossypium turneri Fryxell, from Mexico

Cotton (genus Gossypium) is an important agricultural crop around the world because of its fiber. Gossypium turneri Fryxell is a wild cotton species endemic to the state of Sonora (northwestern Mexico), whose status has been recently raised to endangered in the IUCN Red List. This species has invaluable characteristics that could be useful in the cultivated cotton gene pool. Despite its importance, G. turneri has been studied very little. To the best of our knowledge, no previous study has characterized its seed morphology and cytogenetics. Therefore, in the present study the seed morphology and karyotype of G. turneri were analyzed. Seeds of G. turneri have nonuniform oval shape and brown-gray color. This species produces short fibers attached to its seed surface that are not long enough for commercial use. Our seed sizes were greater than those previously described for G. turneri and other diploid cottons. The length and width of seeds were 8.80 mm and 4.83 mm, respectively. Traits such as embryo and seed coat were measured and carefully observed, and gossypol glands were observed only in the embryo during the evaluation of internal features of seeds. Cytogenetic analysis revealed 26 chromosomes (2n = 2x = 26) in mitotic cells of G. turneri. The karyotype analysis showed mainly metacentric (m), submetacentric (sm) and subtelocentric (st) chromosomes. Our results reveal important biological traits of G. turneri that could be considered in future studies to improve cultivated cotton.

Systematical characterization of YUCCA gene family in five cotton species, and potential functions of YUCCA22 gene in drought resistance of cotton

Auxin plays an essential role in the normal growth and development of plants. The tryptophan aminotransferase of Arabidopsis (TAA)/YUCCA (YUC) enzymes functions as flavin monooxygenases (FMOs), which are the key enzymes in auxin synthesis. However, comprehensive characterization of the YUC gene family in cotton has not yet been completed. In order to reveal the functions of YUC genes in cotton, we systematically identified and characterized the YUC gene family in five species of cotton including analysis of the member, characterization, intragenomic duplication, and collinear relationships. Transcriptomic analysis indicates that GhYUCs participate in abiotic stress processes in cotton. The GhYUC22 gene that is responsive to polyethylene glycol (PEG) and abscisic acid (ABA) was functionally identified via virus-induced gene silencing (VIGS). Subsequent natural drought simulation experiments and physiological index data demonstrated that partial silencing of GhYUC22 gene endowed cotton with drought resistance by modulating indole-3-acetic acid (IAA) and ABA signaling pathways. In conclusion, our findings support the role of that GhYUC22 gene in modulating both endogenous auxin and ABA homeostasis and regulating the drought resistance in cotton.

Genome-wide analysis of CBL and CIPK family genes in cotton: conserved structures with divergent interactions and expression.

The online version contains supplementary material available at (doi:10.1007/s12298-021-00943-1).

Evolution of AITR family genes in cotton and their functions in abiotic stress tolerance.

Abiotic stresses are major environmental factors inhibiting plant growth and development. AITRs (ABA-induced transcription repressors) are a novel family of transcription factors regulating ABA (abscisic acid) signalling and plant responses to abiotic stresses in Arabidopsis. However, the composition and evolution history of AITRs and their roles in the cotton genus are largely unknown. A total of 12 putative AITRs genes were identified in cultivated tetraploid cotton, Gossypium hirsutum. Phylogenetic analysis of GhAITRs in these tetraploid cottons and their closely related species implicate ancient genome-wide duplication occurring after speciation of Gossypium, and Theobroma could generate duplicates of GhAITRs. Duplicated GhAITRs were stably inherited following diploid speciation and further allotetraploidy in Gossypium. Homologous GhAITRs shared common expression patterns in response to ABA, drought and salinity treatments, and drought tolerance induced in transgenic Arabidopsis plants expressing GhAITR-A1. Together, our findings reveal that duplicates in the GhAITRs gene family were achieved by whole genome duplication rather than three individual duplication events, and that GhAITRs function as transcription repressors and are involved in the regulation of plant responses to ABA and drought stress. These results provide insights towards the improvement of abiotic stress tolerance in cotton using GhAITRs.

Exogenous application of acetic acid improves the survival rate of cotton by increasing abscisic acid and jasmonic acid contents under drought stress

Prolonged drought stress could accelerate plant death. In this study the mechanisms of the acetic acid to increase the survival rate of cotton under drought stress were studied. Twenty-day-old cotton seedlings were grown for 9 days in the presence or absence of acetic acid under natural drought conditions in which the relative water content (RWC) of the soil decreased below 60% at 6 days after treatment (DAT). The water potential, photosynthesis (Pn), chlorophyll (Chl) content, stomatal conductance (Cond), and transpiration (Tr) of the control plants started to decrease at 6 DAT. However, acetic acid treatment caused a decrease in Cond and Tr at 3 DAT. Abscisic acid (ABA) and jasmonic acid (JA) contents and the expression of ABA biosynthesis genes (NCED2, NCED3, and NCED9) and JA biosynthesis genes (GhAOS6, GhLOX3, and GhOPR11) in cotton leaves were increased by acetic acid treatment at 3 DAT, and these variables were increased in control and acetic acid-treated plants at 6 and 9 DAT. These results indicate that acetic acid can increase ABA and JA contents by upregulating the expression of their biosynthesis genes, thus decreasing the Cond and Tr, and therefore, increasing the RWC of the soil and increasing the survival of cotton under drought stress.