[Objective] The glycosylphosphatidylinositol-anchored lipid transfer protein (LTPG) genes were identified from the whole genome of Gossypium hirsutum to provide support for subsequent research. [Method] Bioinformatics methods were used to screen and identify the LTPG gene family from the TM-1 genome, and the physicochemical properties of proteins, phylogenetic relationship, gene duplication, gene structure, and cis-acting elements in the promoter region were predicted and analyzed. Transcriptome data and real-time quantitative polymerase chain reaction (qRT-PCR) were used to analyze their expression pattern in different tissues and organs and under different abiotic stresses. The subcellular localization of the target proteins was identified by transient transformation in tobacco leaves. [Result] Ninety-five GhLTPG genes were identified in the G. hirsutum genome, which were clustered into 5 categories by phylogenetic tree analysis. Segment duplication is the main reason for the expansion of the GhLTPG gene family. Ka/Ks analysis indicated that GhLTPG underwent strong purification selection. Transcriptome data analysis showed that some GhLTPG responded to low temperature, high temperature, salt, or drought stress. The results of qRT-PCR analysis showed that GhLTPG11/14/52/62 responded to low temperature, high temperature, salt and drought stress, and GhLTPG24/56 responded to low temperature, salt, or drought stress. Subcellular localization experiments showed that both GhLTPG24 and GhLTPG62 were localized in the cell membrane. [Conclusion] Ninety-five GhLTPG genes were identified in the whole genome of G. hirsutum. Some GhLTPG genes responded to abiotic stresses such as low temperature, high temperature, salt and drought, which laid a foundation for in-depth analysis of the function of specific GhLTPG gene.
[Objective] This study aimed to analyze the mechanism of GhCDPK28-A10 in Verticillium wilt response in cotton, and to provide genetic resources for disease resistance breeding in cotton. [Methods] The homologous sequence of the GhCDPK28-A10 gene was obtained from the cotton genome database and bioinformatic analysis was performed. Real-time quantitative polymerase chain reaction(qRT-PCR) was used to detect the effect of GhCDPK28-A10 gene on the resistance to Verticillium dahliae, methyl jasminate (MeJA), salicylic acid(SA), or H2O2-treated cotton plants. The role of GhCDPK28-A10 in cotton resistance to Verticillium wilt was verified by virus-induced gene silencing (VIGS) technique. [Results] Phylogenetic tree and gene structure analysis showed that the six GhCDPK28-A10 homologs in upland cotton shared similar number of motifs and contained the typical serine/threonine protein kinase structural domain of the CDPK family. Analysis of the promoter sequence revealed that GhCDPK28-A10 contains a cis-acting element in response to jasmonic acid (JA). Tissue-specific expression analysis showed that GhCDPK28-A10 was expressed in root, stem and true leaves. And the highest expression level was found in true leaves. The expression of GhCDPK28-A10 was significantly increased under stress induction by V. dahliae, MeJA, and H2O2. The expression of disease resistance-related genes PR1, NPR1, and PR4 was enhanced and the negative regulator of JA synthesis gene JAZ1 was decreased in GhCDPK28-A10 silenced cotton plants. This indicated that the JAZ1 regulated JA synthesis was inhibited and reactive oxygen species was enriched when the CDPK28-A10 expression level was decreased, which in turn enhanced the resistance to Verticillium wilt of cotton plants. [Conclusion] GhCDPK28-A10 negatively regulates the resistance response of cotton to Verticillium wilt by regulating the expression of defense-related genes, and is a candidate gene for improving the resistance of cotton to Verticillium wilt.
[Objective] Verticillium wilt(VW) is one of the most significant diseases affecting cotton production, and the pathogenesis of VW in cotton is still unclear. By constructing a Gossypium mustelinum introgression population, this study aims to locate quantitative trait loci (QTL) related to VW resistance and provides a reference for the development of molecular markers for VW resistance and assisted breeding. [Method] A BC5S5 population containing 71 introgression lines was constructed using upland cotton (G. hirsutum) B0011 as the recurrent parent and G. mustelinum as the donor parent. The study employed 2 839 single nucleotide polymorphism (SNP) markers to mapping QTL associated with the resistance to VW based on phenotypic values. [Result] A total of 15 QTL related to the resistance to VW were detected, with 4.21% to 26.77% phenotypic variance explained (PVE). Additive effect analysis showed that 6 QTL had favorable alleles originating from G. mustelinum, while 9 QTL had favorable alleles originating from upland cotton B0011. Among these QTL, qVW-A01-1, qVW-A02-2 and qVW-A07-2 were detected in 2 or more environments, and the PVE ranged from 15.56% to 16.56%, 11.95% to 24.62% and 13.22% to 16.73%, respectively. Based on the best linear unbiased prediction (BLUP) value of resistance to VW in the BC5S5 population to re-linkage analysis, 5 QTL were detected. qVW-A01-1B and qVW-A02-1B were consistent with the physical positions of qVW-A01-1 and qVW-A02-2 detected by additive effect analysis, with PVE of 23.67% and 17.90%, respectively. [Conclusion] In this study, 2 stable QTL qVW-A01-1 and qVW-A02-2 were identified, which provide a basis for molecular marker-assisted selection breeding and functional identification of candidate gene in cotton breeding programs aimed at developing cotton resistance to VW.
[Objective] This study aims to clarify the regulatory effects of Glycyrrhiza uralensis strips on population abundances and biocontrol function of Hippodamia variegata, so as to provide references for the rational use of G. uralensis strips to biologically control aphids (Aphis spp.) in cotton fields. [Method] Population abundances of aphids and H. variegata in cotton fields with G. uralensis strips and cotton fields without G. uralensis strips and cotton fields away from G. uralensis strips at different distances(1m, 5m, 10m, 20m) were systematically investigated in Korla of Xinjiang, and the effects of G. uralensis strips on relative growth fold of aphids and biocontrol function of H. variegata were evaluated by using the caged-natural enemy exclusion method. [Result] The high density of Aphis atrata in the G. uralensis strips could conserve a large number of H. variegata in early to mid-June, which is an important source of H. variegata in adjacent cotton fields. A large number of H. variegata occurred in cotton fields from late-June to mid-July. And the ratios of H. variegata to aphids in cotton fields away from G. uralensis strips at 1 m, 5 m, 10 m and 20 m were to varying degrees higher than those of cotton fields without G. uralensis strips from mid-June to late-July. Among them, the ratio of H. variegata to aphids reached the highest (2.502 9) in cotton fields away from G. uralensis strips at 1 m on June 17. The relative population growth folds of aphids in the cages at 7 and 14 days post caging were significantly higher than those in the non-caged correspondingly. Biocontrol index of H. variegata to aphids in cotton fields with G. uralensis strips was significantly higher than that of cotton fields without G. uralensis strips at 14 days post caging. [Conclusion] The G. uralensis strips can effectively increase the population abundances of H. variegata and improve the ratio of H. variegata to aphids, which shows an important regulatory effect on biocontrol function of H. variegata to aphids in cotton fields.
[Objective] The experiment was conducted to study the effect of irrigation frequency on root distribution of cotton plant in Southern Xinjiang under fixed irrigation quota (3 900 m3·hm-2). [Methods] CCRI 96A was planted as the test material, with 76 cm row spacing. Four irrigation frequency treatments were set up as follows: 6 irrigation times (T6, 650.0 m3·hm-2 per time), 8 irrigation times (T8, 487.5 m3·hm-2 per time), 10 irrigation times (T10, 390.0 m3·hm-2 per time), and 12 irrigation times (T12, 325.0 m3·hm-2 per time). The roots in the 0-60 cm soil layer of cotton in the middle row was collected and stratified by the soil root excavation method and scanned by root scanner. Then the root surface area, volume and other indexes were statistically analyzed. [Results] The roots with a diameter of less than 1 mm made up 94.5% of the total root length and 71.9% of the total root surface area. The total root volume was closely related to larger roots. With the increase of diameter, root length, root surface area, and root volume of each treatment decreased first and then increased. In the 0-60 cm soil layer, the root length density (11 662.71 m·m-3), root surface area density (15.61 m2·m-3) and dry matter mass (21.55 g) of T6 treatment were the largest, but the root volume density of T12 treatment (2.2×10-3 m3·m-3) was the largest. Under plough layer (30-60 cm soil layer), the root length density and the dry matter mass of T10 treatment were the largest, at 1 090.46 m·m-3 and 1.09 g, and the root surface area density and the volume density of T8 treatment were the largest, at 2.52 m2·m-3 and 2.68×10-4 m3·m-3, respectively. [Conclusion] Under the same irrigation quota of 3 900 m2·hm-2, rational allocation of irrigation frequency can optimize the morphology and distribution of cotton roots in the soil. It could promote root surface area by increasing the irrigation amount per time to extend the irrigation interval. In this study, T6 treatment was beneficial to the elongation and distribution of cotton roots in the 0-60 cm soil layer, and T12 treatment is beneficial to cotton root thickening.
[Objective] This study aimed to explore the effects of water and nitrogen management on cotton growth and development, water and nitrogen use efficiency, and soil greenhouse gas emissions under non-film drip irrigation cotton fields in Xinjiang. [Method] Two irrigation quotas (W1: 450 m3·hm-2, W2: 540 m3·hm-2) and three nitrogen application rates (150 kg·hm-2, 225 kg·hm-2, 300 kg·hm-2 nitrogen) were set. The differences of total nitrogen content of soil and plant, cotton plant height, cotton stem diameter, seed cotton yield, water and nitrogen use efficiency and soil greenhouse gas emissions were analyzed under different water and nitrogen treatments. [Result] At 225 kg·hm-2 and 300 kg·hm-2 nitrogen application rates, the average total nitrogen content in the 0-80 cm soil layer of W1 was higher than that in the W2 treatment at different growth stages. At the same nitrogen application level, the cumulative emissions of soil CO2, CH4, N2O, global warming potential (GWP), greenhouse gas emission intensity (GHGI) and water use efficiency under W1 treatment were all increased compared with W2. Under W1 treatment, the average total nitrogen content of 0-80 cm soil layer at seedling and squaring periods, cotton plant height and stem diameter at different growth stages, seed cotton yield and water use efficiency all increased with the increase of nitrogen application rate. The cumulative emissions of soil CO2 and CH4, GWP, GHGI and partial productivity of nitrogen fertilizer decreased with the increase of nitrogen application rate, while the total nitrogen content of plant increased first and then decreased with the increase of nitrogen application rate. Under W2 breatment, total nitrogen content of cotton plant, seed cotton yield and water use efficiency all increased first and then decreased with the increase of nitrogen application rate. The cumulative emissions of soil CO2 and CH4, GWP and partial productivity of nitrogen fertilizer all decreased with the increase of nitrogen application rate, while cotton plant height and stem diameter increased with the increase of nitrogen application rate. Through fitting analysis, it was found that the fitting curves of seed cotton yield under W1 treatment and that under W2 treatment intersected when the nitrogen application rate was 278.07 kg·hm-2. [Conclusion] For the Southern Xinjiang region with water shortage, 450 m3·hm-2 irrigation quota and 300 kg·hm-2 nitrogen application rate are efficient water and nitrogen application modes for increasing water use efficiency and cotton yield and reducing emission of soil greenhouse gas under non-film drip irrigation condition.