15 November 2018, Volume 30 Issue 6

    

• Select all
  |

• Select
  Functional Analysis of a Salt Stress Response Gene, GhEXO70B1, in Upland Cotton (Gossypium hirsutum L.)

  Ding Yanpeng, Ge Xiaoyang, Wang Peng, Wu Jie, Wang Xingfen, Li Fuguang

  Cotton Science. 2018, 30(6): 423-434. https://doi.org/10.11963/1002-7807.dyplfg.20181109

  Abstract ( ) Download PDF ( )   Knowledge map   Save

   [Objective] The exploitation of salt-tolerant genes is urgently needed to improve the salt tolerance of cotton and increase its adaptability to saline-alkali soil. [Method] The function and structure of the GhEXO70B1 gene were bioinformatically analyzed. Quantitative reverse transcription-polymerase chain reaction (qRT-PCR) was used to analyze the expression of this gene in different cotton plant parts and in salt-stressed roots, stems, and leaves. Virus-induced gene silencing (VIGS) was applied to verify the function of GhEXO70B1. The degree of stress and the possible physiological mechanism of stress response were comprehensively analyzed through trypan blue staining and biochemical measurements. [Result] In this study, the novel gene GhEXO70B1 involved in autophagy was isolated from upland cotton. Bioinformatic analysis showed that GhEXO70B1, which is a non-secretory protein with a conserved EXO70 domain and no transmembrane structure, is evolutionarily highly conserved. In the qRT-PCR analysis, the gene had higher expression levels in roots and stems than in other tissues and was upregulated by salt stress. After VIGS technology-induced silencing of the expression of GhEXO70B1, cotton plants exhibited yellowing, wilting, and drying of leaves and higher salt sensitivity than the control. Proline content decreased significantly, whereas malondialdehyde content increased slightly and the range of colors of trypan blue-stained leaves was larger; these results indicate GhEXO70B1 silencing significantly decreased the salt stress response ability of upland cotton and significantly increased the level of cell death. [Conclusion] The GhEXO70B1 gene is associated with autophagy, which suggests that this gene responds to adversity stress in upland cotton by mediating autophagy.
  
• Select
  QTL Mapping of Important Agronomic Traits on Chromosomes Showing Marker Segregation Distortion in Interspecific Backcross Cotton Populations

  Dai Baosheng, Guo Huanle, You Chunyuan, Zhang Xianlong, Lin Zhongxu

  Cotton Science. 2018, 30(6): 435-447. https://doi.org/10.11963/1002-7807.dbslzx.20181119

  Abstract ( ) Download PDF ( )   Knowledge map   Save

  [Objective] The purpose of this study was to map QTLs for yield, maturity, and fiber quality traits of cotton interspecific hybrid populations and to mine favorable alleles from the cotton genome for QTL fine mapping, gene cloning, and molecular marker-assisted selection. [Method] Four BC₁F₁ populations, E(E3), E(3E), (E3)E, and (3E)E, were developed by crossing sea island cotton 3-79 ("3") and upland cotton 'Emian 22' ("E"), and with "Emian 22" as the recurrent parent. BC1F2 populations derived from BC1F1 populations were phenotyped to allow mapping of QTLs for yield-, maturity-, and fiber quality-related traits on chromosomes showing segregation distortion. [Result] A normal distribution test indicated that six fiber quality-related traits, except for the micronaire value in E (E3) and the short fiber ratio in all populations, followed a normal distribution pattern; in contrast, earliness-related traits were not normally distributed in all populations, which suggests that genotype-environment interactions have strong effects on maturity-related traits. Using composite interval mapping, 47 QTLs were detected on three chromosomes (2, 16, and 18): 15 in (E3)E, 13 in (3E)E, 12 in E(E3), and 7 in E(3E), with the phenotypic variation explained (PVE) ranging from 8.8%–30.9%. A total of 27 fiber-related QTLs were discovered, with the PVE ranging from 9.0%–30.9%. Five yield-related QTLs (PVE = 8.8%–17.4%) and 13 maturity-related QTLs (PVE = 9.4%–19.4%) were also identified. [Conclusion] Comparison analysis showed that most QTLs in our study were consistent with the MetaQTL, including QTLs for boll weight, fiber length, fiber length uniformity, lint percentage, and micronaire value on chromosome 2; QTLs for fiber length, fiber strength, and fiber length uniformity on chromosome 16; and QTLs for boll weight, date of boll opening, fiber length, fiber strength, fiber length uniformity, and micronaire value on chromosome 18. Several detected QTLs in our study were not found in the MetaQTL, such as QTLs for date of boll opening and lint percentage on chromosome 16 and a QTL for the date from seedling to flowering stages on chromosome 18. These newly identified QTLs may provide novel insights for cotton QTL analysis.
• Select
  Localization of a Dwarfing Mutation in Upland Cotton Using InDel Markers Based on Genome Re-Sequencing Data

  Ji Gaoxiang, He Shoupu, Pan Zhao’e, Gong Wenfang, Jia Yinhua, Wang Liru, Wang Pengpeng, Geng Xiaoli, Du Xiongming

  Cotton Science. 2018, 30(6): 448-454. https://doi.org/10.11963/1002-7807.jgxdxm.20181121

  Abstract ( ) Download PDF ( )   Knowledge map   Save

  [Objective] InDel markers that were developed by comparing whole genome re-sequencing data were used to map the AS98 gene of a dwarf mutant of upland cotton (Gossypium hirsutum L.). [Method] An F2 segregation population was constructed from an upland-cotton dwarf mutant (AS98) and its wild type (LHF10), and InDel markers were developed based on genome re-sequencing data from the two parents. The InDel markers and the F2 generation were then used to map the AS98 gene of the dwarf mutant. [Result] A total of 114 InDel markers located in a previous mapping region were screened and used to genotype 223 F2 individuals. Ultimately, phenotypic data and 20 polymorphic primer pairs were used to construct a genetic linkage map. Molecular marker analysis mapped AS98 within a 6.9 cM distance of the marker InDel-50 on chromosome D12. [Conclusion] This study has demonstrated the feasibility of using InDel markers developed from re-sequencing data for gene localization in isolated populations derived from upland cotton dwarf materials. The resulting gene map provides a basis for future fine mapping and molecular-assisted selection breeding.
• Select
  Evaluation of the Low-Temperature Tolerance of Cotton Varieties in the Huang-Huai Region during Seed Germination

  高利英, 邓永胜, 韩宗福, 孔凡金, 申贵芳, 李汝忠, 尹燕枰

  Cotton Science. 2018, 30(6): 455-463. https://doi.org/10.11963/1002-7807.glyyyp.20181114

  Abstract ( ) Download PDF ( )   Knowledge map   Save

  [Objective] To provide a theoretical foundation and germplasm resources for low-temperature-germination cotton breeding, the germination characteristics of 38 cotton varieties novel to or formerly widely planted in the Huang-Huai Region were evaluated under different low temperature stress conditions. [Method] Analysis of variance, the fuzzy membership function method, and cluster analysis were used to comprehensively evaluate the tolerance of these varieties to low temperature stress. [Result] As the temperature was lowered, germination rate, germination index, and vigor index exhibited a decreasing trend in all cotton varieties, but resistance to low temperature was significantly different among varieties. Cluster analysis divided the 38 varieties into three categories: highly resistant, resistant, and non-resistant. [Conclusion] Early-introduced varieties and those bred from early-introduced germplasm resources had weaker resistance to low temperature stress, with Stoneville and Deltapine series showing the lowest tolerance. The new transgenic insect-resistant cotton varieties SCRC 37 and SCRC 36 had the strongest resistance to low temperature stress.
  
• Select
  Effect of Moderate Drought in the Early Stage on Cotton Yield, Fiber Quality and Water Use Efficiency

  Wan Hualong, Liu Pengcheng, Liu Liantao, Zhang Yongjiang, Liu Yuchun, Bai Zhiying, Li Cundong, Sun Hongchun

  Cotton Science. 2018, 30(6): 464-472. https://doi.org/10.11963/1002-7807.whlshc.20181113

  Abstract ( ) Download PDF ( )   Knowledge map   Save

  [Objective] A 2-year field experiment was conducted to determine the effect of a moderate drought regime in the early-stage on cotton yield, fiber quality and water use efficiency. [Method] An experiment was set up in 2015 and 2016 on the Qingyuan Experimental Plot of Hebei Agricultural University based on a split plot design with two main plots: (1) conventional irrigation (W1) and (2) drought (limited irrigation before sowing with no irrigation during the growing period, W2). Three sub-plots with different cotton cultivars were established: CCRI 50 (early maturity), Nongdamian 601 (ND 601, moderate earliness), and Jimian 958 (JM 958, intermediate maturity). [Result] (1) Drought stress affected the ratio of seasonal bolls. Under drought stress, the ratio of summer bolls decreased and that of autumn bolls increased. Because the precipitation peak in 2016 was higher than normal and mainly concentrated in July, which was later than in 2015, the ratio of autumn bolls increased in 2016. (2) Drought stress affected cotton yield but had no significant effect on fiber quality. Under moderate drought, the boll number per plant and boll weight of ND 601 and JM 958 decreased, the ratio of boll setting increased (P < 0.05), the boll weight of CCRI 50 increased, and the yields of all three cultivars decreased. Because CCRI 50 is an early-maturing cultivar and sensitive to water, its yield decreased significantly (41.0%). (3) Reducing irrigation by an appropriate amount was able to improve water use efficiency. The water use efficiencies of ND 601 and JM 958 averagely increased significantly, by 15.75% and 10.05%, respectively, between 2015 and 2016 under drought stress. The water use efficiency of CCRI 50 decreased significantly, by 15.9%, because of its early maturity and sensitivity to water stress. [Conclusion] Moderate irrigation has a significant effect on yield, fiber quality, and water use efficiency. Cotton yield losses caused by water stress can be ameliorated by making the best use of natural precipitation and by increasing planting density.
• Select
  Research Progress on the Mendelian Genetic Analysis and Molecular Mapping of Morphological Qualitative Traits in Cotton

  Zang Xinshan, Geng Yanhui, Pei Wenfeng, Wu Man, Li Xingli, Zhang Jinfa, Yu Jiwen

  Cotton Science. 2018, 30(6): 473-485. https://doi.org/10.11963/1002-7807.zxsyjw.20181107

  Abstract ( ) Download PDF ( )   Knowledge map   Save

  Genetic analysis and molecular mapping of qualitative traits are important tools in cotton breeding. Research on cotton qualitative traits has been reported since the early 1900s. Rapid advances in cotton genomics and molecular mapping over the past several years have facilitated the mapping and cloning of important qualitative trait genes in cotton. Although most of the 101 genes and alleles related to cotton morphological qualitative traits have not been mapped to linkage groups or chromosomes, several genes have been cloned and identified via map-based cloning. This paper describes research progress on the genetic and linkage analysis, molecular mapping, and candidate gene cloning of eight major types of morphological qualitative traits: plant color, leaf color, leaf shape, bract, flower, nectary, gland, and fiber characteristics. The presented information lays a foundation for studying the molecular basis of qualitative traits, favorable gene-based transfer, and gene pyramiding in cotton.
• Select
  Optimization of an Inoculation Method for Cotton Alternaria Leaf Spot

  Wang Jing, Zhai Weibo, Meng Jing, Gao Huan, Shi Jinyan, Zhang Wenwei, Han Rong, Qi Fangjun

  Cotton Science. 2018, 30(6): 486-491. https://doi.org/10.11963/1002-7807.wjqfj.20180917

  Abstract ( ) Download PDF ( )   Knowledge map   Save

  [Objective] Cotton Alternaria leaf spot disease causes serious damage during cotton production. The aim of this study was the optimization of an inoculation method for cotton Alternaria leaf spot. [Method] An Alternaria alternata spore suspension was used as the inoculum. Three inoculation methods were tested and compared: smearing with spores plus retaining moisture using a sealed plastic bag; smearing with spores plus retaining moisture by intermittently spraying with water; and spraying spores plus retaining moisture by intermittently spraying with water. [Result] Inoculated cotton leaves were most readily infected by smearing with spores plus intermittently spraying with water. This inoculation method was effective for distinguishing resistant cotton cultivars from susceptible ones, but often caused nonuniform disease lesions on cotton leaves; thus, the incidence of diseased leaves was random and somewhat nonuniform. Spraying spores plus retaining moisture by intermittently spraying with water led to a relatively longer disease pathogenesis and slower disease progression; however, the incidence of diseased leaves was relatively consistent and uniform, thus providing repeatable inoculation experimental conditions compared with the other two inoculation methods. [Conclusion] Spraying spores plus retaining moisture by intermittently spraying with water is a suitable inoculation method for studying cotton resistance to Alternaria leaf spot.
• Select
  A Regeneration System for Cotton Variety Xinluzao 45 via Somatic Embryogenesis

  Ge Shuya#, Shen Qiuping#, He Jiming, Lü Zunfu, Zheng Haibiao, Li Feifei

  Cotton Science. 2018, 30(6): 492-497. https://doi.org/10.11963/1002-7807.gsylff.20181113

  Abstract ( ) Download PDF ( )   Knowledge map   Save

  [Objective] The purpose of this study was to expand upland cotton genotypes suitable for regeneration via somatic embryogenesis, so as to provide excellent receptor materials for the genetic transformation of cotton. [Method] Six different hormone combinations were studied to establish a somatic embryo regeneration system for hypocotyl explants of Xinluzao 45, a widely planted variety in Xinjiang Province. [Result] Faint yellow callus was induced on a medium consisting of hormone combinations C1 (0.1 mg·L^－1 acetic acid dichlorobenzene oxide [2, 4-D] + 0.1 mg·L^－1 kinetin [KT]) or C5 (0.1 mg·L^－1 2, 4-D + 0.5 mg·L^－1 indo-3-butyric acid + 0.1 mg·L^－1 KT). The generated callus was able to successfully induce embryogenic callus on hormone-free medium containing doubled KNO3. The embryogenic callus then developed into somatic embryos and regenerated plants. Maximum rates of callus induction and regeneration were 92.2% and 40.3%, respectively. Although no significant difference was observed in the rate of callus induction of Xinluzao 45 hypocotyls between hormone combinations C1 and C5, the incidence of induced embryonic callus was higher on C1 than on C5. [Conclusion] The somatic embryo regeneration system developed in this study provides technical support that will facilitate Agrobacterium-mediated transformation of upland cotton Xinluzao 45.
• Select
  Relationship between Bt Protein Expression and Nitrogen Metabolism in Insect-Resistant Transgenic Cotton Lines with Different Genetic Backgrounds

  Zhao Hongxia, Wang Shijie, Zhu Jijie, Li Miao, Wang Guoyin

  Cotton Science. 2018, 30(6): 498-504. https://doi.org/10.11963/1002-7807.zhxwgy.20181121

  Abstract ( ) Download PDF ( )   Knowledge map   Save

  [Objective] This study aimed to determine the relationship between Bt protein expression levels and nitrogen metabolism in insect-resistant transgenic cotton lines with different genetic backgrounds and to provide some recommendations for the selection of highly insect-resistant cotton cultivars. [Method] Bt protein contents and nitrogen metabolism-related indexes were measured in young leaves, buds, and bolls of 41 cotton lines at different developmental stages (4–6 leaf, flourishing bud, and flourishing boll setting stages), and the correlations among these indexes were analyzed. [Result] The expression level of Bt protein in vegetative organs was found to be highly significantly positively correlated with the contents of soluble protein and free amino acids but not that of total nitrogen. Bt protein expression levels in reproductive organs were highly significantly positively correlated with soluble protein and total nitrogen contents and significantly positively correlated with free amino acid content. While soluble protein levels showed a relatively steady decrease from seedling to bud stages and from bud to boll setting stages, the highest Bt protein contents were measured in reproductive organs in mid- to late periods. [Conclusion] The expression level of Bt protein had the highest positive correlation with soluble protein and can thus be used as a reliable index for selection of highly insect-resistant cotton cultivars.