15 September 2019, Volume 31 Issue 5
    

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    RESEARCH REPORTS
  • Dong Qi,Magwanga Richard Odongo,Lu Pu,Cai Xiaoyan,Zhou Zhongli,Wang Xingfen,Wang Xingxing,Xu Yanchao,Hou Yuqing,Wang Yanqing,Wang Kunbo,Liu Fang,Ma Zhiying
    Cotton Science. 2019, 31(5): 361-380. https://doi.org/10.11963/1002-7807.dqmzy.20190723
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    [Objective] By analyzing the major birch pollen allergen Bet v 1 gene family in D genomes of cotton and comparing the expression patterns of three diploid D-genome cotton varieties with different Verticillium wilt resistance levels, we aimed to provide a theoretical basis for further studies on the role of Bet v 1 genes in cotton resistant to Verticillium wilt. [Method] The Bet v 1 genes were identified, and a bioinformatics analysis of the physicochemical properties of their encoded sequences in Gossypium raimondii (D5) was performed. The transcriptome sequencing and quantitative real time-PCR of G. raimondii (D5), Gossypium trilobum (D8) and Gossypium thurberi (D1) were used to verify the expression patterns of Bet v 1 genes under Verticillium dahlia infection stress. Bet v 1 genes were silenced by virus-induced gene silencing in G. hirsutum to identify their functions. [Result] The D genome of cotton contains 59 members, 58 of which have introns and are distributed on eight chromosomes, and most encode hydrophilic proteins that localize to the cytoplasm. The expression levels of Bet v 1 genes in three wild cotton species having D genomes after being inoculated with V. dahliae were consistent with their disease resistance levels. The genes were separated into three groups based on their expression levels. Genes of Group 3 responded to V. dahliae infection and were highly expressed in disease-resistant cotton species G. thurberi. This indicated that Group 3 genes may be involved in the immune response of Verticillium wilt. A gene with a high expression level was screened out of Group 3. A corresponding homologous gene was silenced in G. hirsutum by virus-induced gene silencing, and gene-silenced plants were more susceptible to V. dahliae, indicating that the gene plays a positive regulatory role in the progress of Verticillium wilt resistance in cotton. [Conclusion] The Bet v 1 genes act in response to V. dahliae infection and are critical in cotton resistance to Verticillium wilt. The information obtained provides a basis for further studies of the cotton Bet v 1 family genes and their functions.

  • Zhang Huachong,Zhang Wenwei,Jian Guiliang,Li Wei
    Cotton Science. 2019, 31(5): 381-393. https://doi.org/10.11963/1002-7807.zhclw.20190715
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    [Objective] Thaumatin-like proteins (TLPs) are important pathogenesis-related proteins that function during disease defense-related responses, participating in the defense reactions triggered by several kinds of pathogen infections. A genome-wide analysis of TLP genes could help increase our understanding of their molecular mechanism in response to Verticillium dahliae infections in cotton (Gossypium hirsutum L.). [Method] The TLP family members in the genomes of the G. hirsutum L. were identified and expression analyses of TLP genes in response to Verticillium dahliae inoculation were conducted using bioinformatics and real-time fluorescent quantitative PCR methods, respectively. [Result] In total, 88 TLP genes were identified in G. hirsutum. These TLPs were classified into 10 groups based on their amino acid sequences and a phylogenetic analysis. A gene structure analysis revealed that the number of exons ranges from 1 to 5, and the number of introns ranges from 0 to 4. TLP genes in the same group shared similar structures. Additionally, most TLP proteins contain five motifs that are arranged in the following order: 5, 4, 2, 3 and 1. In total, 87 TLP genes are distributed on 20 of the 26 chromosomes, and 42 and 45 TLP genes are distributed in the A and D subgroups, respectively. The real-time fluorescent quantitative PCR analysis showed that the expression levels of six candidate TLP genes were induced in both tolerant cotton cultivar GZ-1 and susceptible cotton cultivar 86-1, and showed a higher expression in the former. [Conclusion] These results provide a foundation for future studies of the functions and regulatory mechanisms of TLP family genes.

  • Xu Xiaolan,Xu Zhongping,Guo Xiaoping
    Cotton Science. 2019, 31(5): 394-402. https://doi.org/10.11963/1002-7807.xxlgxp.20190912
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    [Objective] Here, the aim was to create a new cotton (Gossypium hirsutum L.) germplasm with high oleic acid and low linoleic acid contents without affecting the fiber yield and quality. [Method] The fatty acid desaturation 2-1 (FAD2-1) gene catalyzes the formation of polyunsaturated linoleic acid from monounsaturated fatty acid in cotton. The protein's properties, structure and functions were analyzed using the information analysis method. A conserved 381-bp fragment of GhFAD2-1 was cloned to construct an RNA interference vector, which was transformed into cotton by Agrobacterium-mediated hypocotyl infection. The fatty acid compositions and contents of T2-T4 transgenic plants were determined using gas chromatography-mass spectrometry. The T4 transgenic lines were used to investigate the copy number, target gene expression, agronomic traits, and fiber quality. [Results] The RNA interference vector of GhFAD2-1 was successfully constructed and transformed into cotton. The target gene's expression level was significantly lower in transgenic plants than in controls. The transgenic plants had high oleic acid and low linoleic acid contents, which could be stably inherited by the offspring. The oleic acid contents of transgenic cotton seeds increased by 224.1%, and the linoleic acid content decreased by 237.5%, compared with the control seeds. There were no significant differences in the agronomic traits and fiber quality of the transgenic lines compared with the control. [Conclusion] These results verified the function of GhFAD2-1 in cotton and provide a basis for breeding cotton varieties with high oleic acid contents.

  • Ju Feiyan,Zhang Siping,Liu Shaodong,Ma Huijuan,Chen Jing,Ge Changwei,Shen Qian,Zhang Xiaomeng,Liu Ruihua,Zhao Xinhua,Zhang Yongjiang,Pang Chaoyou
    Cotton Science. 2019, 31(5): 403-413. https://doi.org/10.11963/1002-7807.jfypcy.20190904
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    [Objective] The aims of this study were to identify the co-expression modules of genes related to the internode elongation of fruiting branches in cotton and to identify the associated hub and candidate genes. [Method] The transcriptome data of 18 fruiting branch internodes from two cotton cultivars (XLZ77 and L28) having significant differences in plant architecture were analyzed. The modules were divided using a weighted gene co-expression network analysis. The selection of specific modules and identification of hub genes were based on a functional enrichment analysis and the gene expression pattern of each module. The weighted co-expression gene network was constructed using Cytoscape_3.3.0. [Result] In total, 34 559 effective genes were screened to construct a co-expression network, and 13 co-expression modules were obtained. Using gene ontology and a Kyoto Encyclopedia of Genes and Genomes enrichment analysis of each module, along with the gene expression patterns in the module, the Cyan module was selected as being related to internode elongation of cotton fruiting branches. Jasmonate-zim-domain protein (JAZ) genes in the plant hormone signal transduction pathway were identified as hub genes in this module. In total, 80 potential candidate genes were identified using the JAZ hub genes, and a gene interaction regulatory network was constructed. [Conclusion] JAZ genes play important roles in inhibiting the internode elongation of fruiting branches in cotton. This study provides supporting data for studies on regulatory mechanisms of cotton fruiting branch elongation and lays a theoretical foundation for the future regulation of cotton plant architecture.

  • Zhang Sujun,Tang Liyuan,Li Xinghe,Wang Haitao,Liu Cunjing,Zhang Xiangyun,Zhang Jianhong
    Cotton Science. 2019, 31(5): 414-426. https://doi.org/10.11963/1002-7807.zsjzjh.20190911
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    [Objective] Molecular markers associated with agronomic and yield-related traits could provide useful references for improving the efficiency of Gossypium hirsutum breeding. [Method] In 147 upland cotton materials, 237 Simple Sequence Repeat(SSR) markers were assayed for polymorphisms. The population structure was analyzed using Structure 2.2. An association analysis between SSR markers and the agronomic and yield-related traits was performed using the Tassel 2.1 General Linear Model program. [Result] The average coefficients of variation for the five indicators varied from 7.28% to 21.06%, with an average of 13.47%, which indicated that the test population had a rich phenotypic diversity. The 237 SSR markers included 690 alleles belonging to 281 loci, with an average of 2.455 0 alleles per SSR marker (ranging from 2 to 6), and the average polymorphism information content value was 0.216 5. The test group could be divided into seven subgroups using Structure software. A genome-wide association analysis was conducted on five agronomic and yield-related traits from 2013 to 2015. There were 45 SSR loci and 1 locus significantly (P<0.01) associated with boll weight and lint percentage, which were detected in 3 or more environments, and they explained 19.30% and 11.58%, respectively, of the phenotypic variation in the different environments (P<0.01). Nine loci were significantly (P<0.01) associated with agronomic traits at two or more bowing times, and one, four and four markers were associated with fruit branch number, boll number and plant height, explaining 9.96%, 7.00% and 5.57%, respectively, of the phenotypic variation in different environments. Sites significantly associated with boll weight, fruit branch number and plant height were simultaneously detected near BNL2448. [Conclusion] Many loci associated with the yield and other important agronomic traits of upland cotton were repeatedly detected in different environments using an association analysis. The results provide useful reference information for cotton molecular marker-assisted selection-based breeding.

  • Li Teng,Han Yingchun,Xiong Shiwu,Wang Zhanbiao,Li Xiaofei,Wang Guoping,Wang Kangli,Li Yabing
    Cotton Science. 2019, 31(5): 427-437. https://doi.org/10.11963/1002-7807.ltlyb.20190909
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    [Objective] Here, the spatial and temporal distributions of soil available phosphorus (AP) were investigated during cotton growth stages in wheat-cotton double-cropping systems in northern Henan, China. [Method] Using the spatial grid sampling and geo-statistical analysis methods, we analyzed the spatial and temporal distributions of soil AP in a cotton monoculture, wheat-cotton 3-1 intercropping system (3-1) and wheat-cotton 6-2 intercropping system (6-2) during the wheat and cotton co-growth stage and the key growth stages of cotton only. [Result] The AP contents were significantly influenced by the cropping systems on different dates. In the co-growth stage, the AP content in the cotton monoculture was higher than that in 3-1, at 20.98% on May 12 and 24.26% on June 7. After wheat was harvested (July 3 and August 4), there were no significant differences among the three cropping systems, and in the boll-opening stage of cotton, the order of the AP contents were as follows: cotton monoculture>6-2>3-1. In the vertical direction, the AP contents decreased as the soil depth increased, while in the horizontal direction, the AP distribution was influenced significantly by the cropping system. Based on the semivariance, there were strong spatial dependencies in the vertical direction in all three cropping systems. [Conclusion] Wheat-cotton double-cropping systems changed the distribution of soil AP, but had no influence on the spatial heterogeneity of the soil AP in the vertical direction. Geo-statistics provide a more intuitive method and guide to study the soil nutrients of the wheat-cotton and other double-cropping systems.

  • Chen Li,Liu Liantao,Ma Tongtong,Jiang Dan,Sun Hongchun,Zhang Yongjiang,Zhang Ke,Bai Zhiying,Li Cundong
    Cotton Science. 2019, 31(5): 438-447. https://doi.org/10.11963/1002-7807.cllcd.20190905
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    [Objective] Cotton (Gossypium hirsutum L.) seed germination, in which melatonin plays an important regulatory role, is seriously affected by soil salinization. Cotton seed germination, antioxidant enzyme activity levels and other physiological indicators were analyzed to clarify the regulatory effects of exogenous melatonin on cotton seed germination under salt-stress conditions. [Method] The experiment was conducted in a greenhouse of Hebei Agricultural University in Baoding City, Hebei Province from 2018 to 2019 using Guoxin Cotton 9 as the material. The germination rate, germination potential, seed biomass after germination, superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) activities, as well as the malondialdehyde (MDA) content, of cotton seeds were measured after exposure to different melatonin concentrations (0, 10, 20, 50 and 100 μmol·L-1) and 150 mmol·L-1 NaCl treatments. [Result] After germination, the germination rate, germination potential, radical length and seed biomass significantly decreased, as did the SOD, POD and CAT activities. However, the MDA content significantly increased under salt-stress conditions. Low exogenous melatonin concentrations (10 and 20 μmol·L-1) increased the germination potential, germination rate and biomass of cotton seeds, and promoted the elongation of radicals; however high melatonin concentrations (50 and 100 μmol·L-1) inhibited cotton seed germination and decreased seed biomass after germination. Low melatonin concentrations (10 and 20 μmol·L-1) increased the SOD, POD and CAT activities and decreased the MDA content in cotton seeds. [Conclusion] Low melatonin concentrations could promote germination and improve the salt tolerance of cotton seeds, while high melatonin concentrations could inhibit their germination. A 20 μmol·L-1 melatonin concentration is appropriate for regulating cotton seed germination under salt-stress conditions.

  • Deng Fangning,Zumilaiti Tuergan,Lin Tao,Kong Song,Dilibaier Dilimaimaiti,Wu Fengquan,Tang Qiuxiang
    Cotton Science. 2019, 31(5): 448-458. https://doi.org/10.11963/1002-7807.dfntqx.20190702
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    [Objective] Plastic film-based mulching is widely used to improve water harvesting and crop productivity in semiarid areas. It is also extensively used for cotton (Gossypium hirsutum L.) production in inland northwestern China, especially in temperature-and rainfall-limited areas. However, it is unclear whether the technology can sustainably maintain the soil water level and salt balance. The primary objectives of this study were as follows: (i) to determine whether different durations of plastic film-based mulching influenced temporal and spatial variations in soil salinity in drip-irrigated cotton fields; and (ii) to determine the optimum duration for plastic film-based mulching. [Method] We imposed six treatments, plastic film-based mulching continuously for 40, 55, 70, 85, and 100 d, as well as a control (CK) for the whole growth period, in drip-irrigated cotton fields in the oasis of southern Xinjiang. [Result] The mean soil water content in the 0-80-cm layers increased as the plastic film-based mulching duration increased. Compared with CK, the soil water content decreased from 14.5% to 7.5% from 40 d to 85 d, and the soil water content of the 100-d film mulching treatment was 4.4% greater than that of the CK. The average soil salt content increased as the plastic film-based mulching duration decreased, and there was a greater influence on the 0-40-cm soil layer than on the 60-80-cm soil layer. The longer the film mulching duration, the greater the salt suppression effect. However, after a plastic film-based mulching duration of more than 100 d, the moisture preservation and salt suppression began to decline. [Conclusion] The 85-d to 100-d period in which salt suppression was associated with plastic film-based mulching approximately covers the whole cotton growth period. These results provide a theoretical basis for the control of soil salinization and for maintaining high yields in the cotton fields of Xinjiang.