[Objective] The REM (Reproductive meristem) gene family encodes a class of transcription factors, which plays an important role in the growth and development of plants. However, it has not been reported in Gossypium hirsutum. [Methods] In this study, REM gene family were systematically identified via bioinformatics based on the third generation genomic data of G. hirsutum and the transcriptome data from public databases. The physical and chemical properties of REM protein, gene structure, gene expression patterns in different tissues and under different stresses for REM family were analyzed. [Results] REM gene family in G. hirsutum contained 79 members which distributed on 25 chromosomes and could be divided into five subfamilies. Each of REM proteins contained at least one B3 domain, and most of the members were located in the nucleus. Cis-acting elements responding to hormone and stress were located in the upstream 2 kb of genes. Gene expression analysis showed that most of the REM genes displayed higher expression in the ovules or fibers than in other tissues, and 29 REM genes responded to cold, hot, salt or drought. Expression patterns of six genes in different developmental stages detected by qRT-PCR(Quantitative real-time ploymerase chain reaction) were basically consistent with transcriptome data. [Conclusion] The distribution in the genome, gene structure, and phylogenetic characteristics of these genes were determined, and the roles of REM genes in growth, development and stress were preliminarily clarified according to transcription profile.
[Objective] Nudix hydrolases, which catalyze the hydrolysis of nucleoside diphosphate derivatives, play an important role in maintaining the stability of genetic material and responding to biotic and abiotic stresses. The purpose of this study is to conduct a genome-wide analysis of the Nudix genes in Gossypium hirsutum and to provide a reference for further functional study of the Nudix genes associated with cotton fiber development. [Methods] Through bioinformatics methods, the whole-genome identification of the Nudix genes was carried out in G. hirsutum genome (ZJU_v2.1), and the physicochemical properties, sequence characteristics, gene duplication, phylogenetic evolution and expression profiles of the GhNudix gene families were systematically analyzed. [Results] A total of 76 GhNudix genes were identified from the G. hirsutum genome and were further divided into seven subgroups by phylogenetic analysis (Clade Ⅰ, Ⅱ, Ⅲ, Ⅳ, Ⅴ, Ⅵ and Ⅶ). Gene duplication analysis showed that segmental duplication was the main force for the amplification of GhNudix genes in G. hirsutum. According to transcriptome data, GhNudix genes expressed with not only tissue-specificity, but also time-specificity. GhNudix genes, which highly expressed during the initial and elongation stages of fiber development, mainly distributed in Clade Ⅰ and Ⅱ; most of the GhNudix promoters of the Clade Ⅰ and Ⅱ subgroups contain cis-elements that respond to auxin and gibberellin. Therefore, we speculated that the GhNudix genes of Clade Ⅰ and Ⅱ subgroups play roles in the initiation and elongation of upland cotton fibers. [Conclusions] Genome-wide identification and analysis of the GhNudix gene family in G. hirsutum will provide a reference for the follow-up study of its biological mechanism in cotton fiber development.
[Objective] The aim of this study is to deeply analyze the molecular genetic mechanism of cotton plant architecture and growth period traits, and to accelerate the process of molecular marker-assisted breeding of machine-picked cotton varieties. [Method] QTL (Quantitative trait loci) mapping was conducted for plant height (PH), node of the first fruiting branch (NFFB), height of NFFB (HNFFB), first node length of the forth fruiting branch(FNLFFB), first node length of the seventh fruiting branch (FNLSFB), flowering time (FT), flowering to boll-opening period (FBP), and whole growth period (WGP), based on a high density genetic map and an F2 population containing 413 plants. [Result] The 8 observed traits showed continuous and bidirectional super affinity distribution. Significant positive correlations were found among the traits. A total of 36 additive effect QTL (aQTL) were mapped, including 14 PH-related aQTL, 6 NFFB-related aQTL, 3 HNFFB-related aQTL, 5 FNLFFB-related aQTL, 3 FNLSFB-related aQTL, 2 FT-related aQTL, 2 FBP-related aQTL, and 1 WGP-related aQTL. Each aQTL could explain 1.70%-10.38% of the phenotypic variation (PV). Three aQTL overlapping regions were found on 3 chromosomes (Chr.), including qNFFB-A11-1 and qWGP-A11-1 on Chr. A11, qHNFFB-D3-1 and qPH-D3-1 on Chr. D3, qNFFB-D8-1 and qFNLSFB-D8-1 on Chr. D8. In addition, 263 epistatic effect QTL (eQTL) were detected, and each eQTL contributed 1.17%-6.19% for PV. And 21 eQTL overlapped with 19 aQTL. A total of 17 aQTL and 202 eQTL distributed on the At genome, and 19 aQTL and 61 eQTL distributed on the Dt genome. [Conclusion] This study laid a foundation for exploring the molecular genetic mechanism of cotton plant architecture and provided theoretical guidance for molecular marker assisted breeding of machine-picked cotton.
[Objective] The distribution characteristics of canopy temperature in different types of cotton varieties were clarified; the relationship between canopy temperature and photosynthetic characteristics was explored, and the possible index for evaluating cotton maturity was identified. [Method] Six cotton varieties were selected, and the digital images of canopy temperature were obtained by using UAV (Unmanned aerial vehicle) carried thermal infrared thermometer from the flowering to the first boll opening period. Meanwhile, the transpiration rate, stomatal conductance and other photosynthetic indexes in the same period of time were measured. [Result] The results showed that the temperature depression of different levels of CCRI 50 were in the following order: the upper layer > the lower layer > the middle layer, and CCRI 60 is just the opposite. In the same day, of all cotton varieties, canopy temperature at 13:30 was greater than 10:30. In addition, transpiration rate of different types of cultivars was positively correlated with stomatal conductance and negatively correlated with canopy temperature. At the Euclidean distance of 12.5, six cultivars could be clustered into two categories. At the Euclidean distance of 5, each category could be divided into two subcategories by the clustering analysis. The two subclasses within the first category were as follow, the first subclass: CCRI 60 and Ji 228; the second subclass: CCRI 3799. The two subclasses within the second category were as follow, the first subclass: CCRI 50 and TQ No.1; the second subclass: 0 Shi. [Conclusion] The change of canopy temperature of different cotton varieties was different. The cluster grouping of cotton varieties based on canopy temperature and photosynthetic index roughly correspond to the maturity types according to the growth period.
[Objective] Leaf mass per area (LMA) is the core index of functional trait relationship network in leaf economic spectrum, which is affected by various environmental factors. However, the effects of systemic regulation on the variation of LMA at different positions of leaves in plant are not clear. [Method] In this study, LMA and tissue structure character of leaves at different positions in cotton were measured by field density experiment and indoor shading experiment. The relationship between LMA and different parts of tissue structure character, and respective influencing factors were analyzed. [Result] Leaf thickness, palisade tissue thickness, cell tense ratio and spongy ratio were affected after the change of light environment at the lower leaves of cotton, which resulted in the variation of LMA. Meanwhile, the structural characteristics of top leaves showed similar trend to lower leaves due to the systematic regulation. The palisade tissue thickness had the most significant effect on LMA in leaves at different positions. [Conclusion] The variation of LMA of top leaves in cotton is controlled by the light environment of lower leaves, and the variation of LMA of cotton leaves is mainly affected by palisade tissue thickness under the systematic regulation.
[Objective] Late planting, increasing density and reducing nitrogen input are effective ways for cotton production in the Yangtze River Basin to reducing input costs through shortening the production cycle. However, the appropriate sowing date is an important factor of cotton production in the mode of sowing after wheat or rape. [Method] A series of sowing date experiments with five sowing date treatments, named 05-20, 05-25, 05-30, 06-04, 06-09, were carried out at four sites of the main cotton-producing areas of Hubei province to study the effects of different sowing times on the growth process, field appearance, yield and quality of cotton in 2018 and 2019. [Result] The results showed that the growth process of cotton was accelerated through shortening the sowing-emergence period and the seedling period; the whole growth period was shortened, and fiber quality of cotton was stable with postponing sowing. However, with the delay of sowing, bolls before Aug 15, bolls per plant, bolls per square meter, seed cotton yield and rate of opened bolls at maturity declined. Especially, when the sowing date is too late, the number of bolls, rate of opened bolls and yield would be significantly reduced. [Conclusion] The suitable sowing date for cotton production in the mode of wheat or rape continuous cotton in the Yangtze River Basin is recommended to around May 25, but no later than June 4.
The application of film mulching technology has made a great contribution to the improvement of cotton yield in China. However, with the long-term use of the PE(Polyethylene) film, the soil residual film pollution was more and more serious, which is becoming a great threat to the soil environment and sustainable production of cotton. In this paper, the present situation, distribution characteristics, and harm of plastic film residue to cotton growth in cotton field were summarized. The damage mechanisms of residual film pollution were systematically summed up from the aspects of soil structure change, water migration, release of harmful substances, soil material metabolism and microbial population structure. And the research progress, advantages and disadvantages of residual film prevention technology were also reviewed. Furthermore, the strategy and development trend of residual film prevention and control technology were proposed, which provided a scientific reference for the researchers on the control technology of cotton residual film pollution in China.
[Objective] This study aims to screen high-efficiency biogenic pesticides and explore their effects on three main detoxification enzymes cytochrome P450 monooxygenase (P450), glutathione S-transferase (GST) and carboxylesterase (CarE) of Thrips tabaci. [Method] The T. tabaci collected from the cotton field and kept in the laboratory was used as the tested insects, and the toxicities of the seven biogenic pesticides to the thrips were measured in laboratory by leaf dipping method. Meanwhile, three insecticides which showed excellent pesticidal activity were selected to conduct the filed efficacy trials. In addition, the activities of the three main detoxification enzymes in T. tabaci were assayed after treatment at the sublethal concentration (LC25) dose of the three insecticides. [Result] (1) The order of toxicity of the seven biogenic pesticides from high to low was: spinetoram, spinosad, matrine, azadirachtin, pyrethrins, rotenone and veratrine. Spinetoram, spinosad and matrine had good insecticidal activity to T. tabaci, and the median lethal concentration (LC50) were 0.011 mg·L-1, 0.274 mg·L-1 and 1.479 mg·L-1, respectively. (2) Field efficacy test showed that the control effects reached more than 90% on the 7th day after treatment of 60 g·L-1 spinetoram suspension concentrate at 2 g, 4 g and 6 g per 666.7 m2 and 5% (Mass fraction) spinosad suspension concentrate at 10 g per 666.7 m2, which were better than the 30% thiamethoxam suspension concentrate and the 1.3% matrine aqueous solution. (3) With the LC25 dose treatment of spinetoram after 48 hours, the activities of P450, GST and CarE increased. But only the activities of CarE increased after treatment with matrine and spinosad, and the activities of P450 and CarE increased after treatment with thiamethoxam. [Conclusion] Spinetoram, spinosad and matrine had high toxicity to T. tabaci, and can be used to control cotton T. tabaci. CarE may participate in the detoxification metabolism of T. tabaci to spinosad and matrine, and the three main detoxification enzymes may participate in the detoxification metabolism of T. tabaci to spinetoram.
