[Objective] A disease that damages cotton fiber has been found in the Xinjiang cotton fields in recent years. The infected cotton fiber turned into mouse-gray and failed to fluff as the boll opens, losing all commercial value. The purpose of this study was to identify the pathogen causing lint rot in Xinjiang cotton fields, and to explore the relationship between mite and disease transmission. [Methods] A total of 161 diseased boll samples were collected from 25 cotton-growing units across northern and southern Xinjiang in 2021 and 2023. The strains were isolated and purified using the tissue isolation method. The pathogen was identified based on morphological characteristics, molecular biological analysis, and pathogenicity test. Different tissues and organs of cotton plants were artificially inoculated in the field to determine the infection sites of the pathogen. The correlation between cotton boll rot and mite was investigated by examining the occurrence frequency of the mite in diseased bolls in cotton field, and combining with the experiment of artificially inoculating healthy detached cotton bolls with mites carrying conidia. [Results] The cotton Nigrospora lint rot is widespread in Xinjiang cotton fields, and the damage is gradually worsening. A total of 146 Nigrospora strains were isolated from diseased samples collected from cotton fields in Xinjiang. The morphological characteristics of the strains were consistent with N. gorlenkoana. The DNA sequences of the internal transcribed spacer in eukaryotic ribose rDNA-ITS, translation elongation factor TEF1-α, and β-tubulin TUB2 in 27 representative strains exhibited high homology with N. gorlenkoana. Field and laboratory pathogenicity tests of 5 representative strains showed that the lint displayed extensive black-gray rot. Therefore, the pathogen causing cotton Nigrospora lint rot in Xinjiang was identified as N. gorlenkoana. The pathogen exclusively infected cotton fiber and did not affect seed, leaf, stem, bud, and flower of cotton. Siteroptes reniformis was closely associated with cotton Nigrospora lint rot. Adult mites or their physogastric females were found in all the diseased bolls, and they can carry the conidia of N. gorlenkoana into the bolls to spread the disease. [Conclusion] The cotton lint rot caused by N. gorlenkoana in Xinjiang in recent years is a disease specifically targeting cotton fiber, with S. reniformis as the primary transmission vector.

[Objective] This study aimed to investigate the role of sucrose in cotton resistance against Verticillium wilt and verify the function of GhSWEET55, providing a theoretical basis for revealing the molecular mechanism of cotton resistance to Verticillium wilt. [Methods] Cotton were inoculated with Verticillium dahliae using the root-wounding method. Sucrose content in cotton roots was determined by spectrophotometry. Differentially expressed genes were obtained by transcriptome sequencing. The enrichment of differentially expressed genes was studied by KEGG pathway analysis. Differentially expressed genes and SWEET family expression patterns were analyzed by transcriptome sequencing, and validated by quantitative real-time polymerase chain reaction (qRT-PCR). Bioinformatics analysis was performed to characterize the protein sequence features and phylogenetic relationships of GhSWEET55, and its expression pattern was analyzed by qRT-PCR. The function of GhSWEET55 was verified by virus-induced gene silencing (VIGS). [Results] Sucrose content in cotton roots increased significantly at 12 h and 48 h after V. dahliae infection, and decreased significantly at 96 h after V. dahliae infection. Some differentially expressed genes were enriched in sucrose-related energy metabolism pathways and defense response pathways. Most members of the SWEET family were differentially expressed, and GhSWEET55 from Clade III was significantly up-regulated. GhSWEET55 was predominantly expressed in cotton leaves, and the encoded protein was localized to the plasma membrane. Silencing of GhSWEET55 enhanced cotton resistance to Verticillium wilt. [Conclusion] Sucrose is involved in cotton resistance against Verticillium wilt. The SWEET gene family responds to V. dahliae infection. GhSWEET55 negatively regulates cotton resistance to V. dahliae.

[Objective] Forkhead box protein G1 (FOXG1), as a transcription factor, plays a crucial role in cell proliferation and differentiation. At present, the FOXG1 gene family has not been systematically studied in cotton. This research aimed to identify and analyze FOXG1 gene family in cotton. [Methods] FOXG1 gene family members were identified in cotton using bioinformatic approaches. Analyses were performed on the physicochemical properties, conserved motifs, and phylogenetic relationships of the corresponding proteins. The expression patterns of FOXG1 genes in Gossypium hirsutum and G. barbadense were investigated using transcriptome data. Preliminary functional exploration of the FOXG1 genes was conducted through association analysis between haplotypes of G. hirsutum FOXG1 genes and fiber quality traits, as well as via transgenic overexpression of GhFOXG1-4 gene in Arabidopsis thaliana. [Results] A total of 6, 5, 3, 3, 6, 6, 6, and 3 FOXG1 genes were identified in G. hirsutum, G. barbadense, G. raimondii, G. arboreum, G. tomentosum, G. mustelinum, G. darwinii, and G. herbaceum, respectively. These 38 FOXG1 proteins and 3 FOXG1 proteins of A. thaliana could be divided into 4 clades. GhFOXG1-1 was highly expressed in anther and ovule. GhFOXG1-2, GbFOXG1-1 and GbFOXG1-2 were highly expressed in anther, ovule and fiber. GhFOXG1-4 was highly expressed in ovule. GhFOXG1-4 and GhFOXG1-5 had 2 and 3 haplotypes, respectively. Significant differences in upper half mean length, breaking strength, and micronaire were observed among these haplotypes. The stem cell width of A. thaliana overexpressing GhFOXG1-4 gene was significantly larger than that of wild type. [Conclusion] A total of 38 FOXG1 genes were identified in 8 cotton species. The excellent haplotypes of some GhFOXG1 genes have the potential to synergistically improve fiber quality. GhFOXG1-4 positively regulates the stem cell width in A. thaliana, which lays a foundation for further study the function of FOXG1 family genes.

[Objective] To address the issues of idle field in winter and spring, low utilization efficiency of cotton straw, and declining profitability in cotton production in the Yellow River Basin, a cotton-Stropharia rugosoannulata double cropping system was proposed, which utilize crushed cotton straw for S. rugosoannulata cultivation in the winter fallow field, followed by S. rugosoannulata residue returning to field. The objective was to investigate the comprehensive effects of this system on productivity, economic benefit, and soil fertility, aiming to provide technical support for the green and sustainable development in the local cotton-growing region. [Methods] Field experiments were conducted from 2022 to 2024 in Linqing City, Shandong Province. Using monocropped spring cotton (MFC) and monocropped short-season cotton (MSC) as controls, the annual yield, economic returns, and soil nutrient content dynamics of two double cropping patterns, intercropping of spring cotton with S. rugosoannulata (FC+SR), short-season cotton followed by S. rugosoannulata in succession planting (SC+SR), were systematically compared. [Results] Compared with MFC treatment, the seed cotton yields of FC+SR and SC+SR treatments significantly decreased by 7.7% and 14.2%, respectively. However, by harvesting S. rugosoannulata (fresh yield: 20.80-21.53 t·hm^-2), the system's net profit was significantly increased to 216 700-244 100 yuan·hm^-2, which was 43.3-48.8 times that of MFC treatment. The net profit of SC+SR pattern was 12.6% higher than that of the FC+SR pattern. Compared with monocropped cotton, the double cropping patterns combined with straw and S. rugosoannulata residue returning significantly increased the contents of alkali-hydrolyzable nitrogen, available phosphorus, and available potassium in the 0-20 cm, 20-40 cm, and 40-60 cm soil layers. And the improvement effect of the SC+SR pattern was generally superior to that of FC+SR. [Conclusion] The cotton-S. rugosoannulata double cropping system is feasible in the Yellow River Basin, with the short-season cotton followed by S. rugosoannulata in succession planting (SC+SR) being the preferred choice. This pattern achieved the recycling of field straw resources and synergistic enhancement of economic benefits and soil fertility, serving as an effective pathway for promoting high-quality agricultural development in the cotton-growing regions of the Yellow River Basin.

[Objective] This study aims to address the issues of impurity contamination in machine-picked seed cotton in Xinjiang and the low efficiency of manual sorting, we propose a highly efficient and precise method for detecting impurities in seed cotton to enhance cotton quality. [Methods] An improved CID-YOLO model is introduced based on YOLO v11. Firstly, a normalization-based attention mechanism module is introduced to enable the network to balance target channel features and pixel features while reducing parameter count and computational complexity, thereby improving detection accuracy. Secondly, according to the characteristics that the detected target is easy to appear at the edge, the lightweight adaptive convolution module is used to replace some convolution modules in the backbone network and neck network, which can better preserve the edge and structure information of the sampling phase, and effectively reduce the amount of parameters. Finally, an efficient layer aggregation network is used to replace the improved pyramid pooling module in the backbone network to enhance the ability of feature multi-scale extraction and information aggregation, so as to improve the perception performance of targets of different scale targets in complex background. [Results] Experimental results demonstrate that the CID-YOLO model achieves outstanding performance in seed cotton impurity detection, with a detection accuracy of 92.1%, recall of 89.5%, F₁ score of 90.8%, and mean average precision of 92.8%. Its overall recognition effectiveness significantly outperforms existing YOLO series models. [Conclusion] The proposed CID-YOLO method enables rapid and precise identification of drip irrigation tapes, colored impurities, cotton stalks, and plastic mulch in machine-picked seed cotton. It provides effective technical support for real-time seed cotton impurity detection and holds promising application prospects.

[Objective] This research aimed to investigate the effects of reclaimed water irrigation and different mulching methods on cotton growth, yield, and fiber quality. [Methods] A field experiment was conducted in Hutubi County, Changji Hui Autonomous Prefecture, Xinjiang in 2024. Six treatments were established: well water irrigation throughout the whole growth stage + straw mulching (T₁); reclaimed water irrigation throughout the whole growth stage + straw mulching (T₂); reclaimed water irrigation at critical water-demand stages (squaring stage and flowering and boll-setting stage) + straw mulching (T₃); reclaimed water irrigation throughout the whole growth stage + plastic film mulching (T₄); reclaimed water irrigation at critical water-demand stages + plastic film mulching (T₅); and well water irrigation throughout the whole growth stage + plastic film mulching (CK). Cotton plant height, stem diameter, leaf area index (LAI), yield traits, irrigation water use efficiency (IWUE), and fiber quality were compared across different treatments. The entropy-weighted technique for order preference by similarity to ideal solution (TOPSIS) method was used for comprehensive evaluation to select the optimal treatment. Meanwhile, the heavy metal contents in the soil and different cotton organs were determined and analyzed. [Results] During the flowering and boll-setting stage, and boll-opening stage, reclaimed water irrigation significantly increased plant height, stem diameter, and LAI compared with well water irrigation. The plant height, stem diameter, and LAI under straw mulching were greater than those under plastic film mulching; the T₂ treatment exhibited the maximum plant height, stem diameter, and LAI. T₂ also achieved the highest seed cotton yield, lint yield, and IWUE, and upper half mean length, breaking tenacity, breaking elongation, and micronaire of fiber of T₂ were superior to those of other treatments. Comprehensive evaluation using entropy-weighted TOPSIS showed that the T₂ treatment performed best. Compared with well water irrigation, reclaimed water irrigation significantly increased the contents of chromium (Cr) and lead (Pb) in the 0-60 cm soil layer and Cr content in cotton roots, stems, and leaves, while significantly reducing the arsenic (As) content in the 0-60 cm soil layer and cotton roots. However, the contents of mercury (Hg), cadmium (Cd), Cr, Pb, and As in soil and cotton plants under different treatments were all below the risk screening values. [Conclusion] Under the conditions of this experiment, the combination of reclaimed water irrigation throughout the whole growth stage and straw mulching showed the best comprehensive performance.

[Objective] Construct a yeast two-hybrid (Y2H) library of Gossypium barbadense, and screen for interacting proteins of GbbHLH130 using Y2H assays. [Methods] This study constructed a Y2H library of G. barbadense using the Gateway technique, and employed the Y2H system to screen for candidate proteins interacting with GbbHLH130. [Results] This study successfully constructed a G. barbadense Y2H library, with a second library capacity of 1.36 × 10⁷ CFU, and insert fragment length >1 000 bp, and a recombination rate of 100%. Using Y2H technology, 298 initial positive clones were screened, and the interaction between GbRAV1, GbHSFA1b, and GbbHLH130 was verified through Y2H assays. [Conclusion] This study successfully constructed a Y2H library of G. barbadense and preliminarily screened candidate interacting proteins for GbbHLH130. GbRAV1 and GbHSFA1b were verified to interact with GbbHLH130 through Y2H assays, suggesting that they may play a role in the biological process of response to drought stress mediated by GbbHLH130. However, their interaction mechanisms and specific roles in drought response need further research.

[Objective] This study aimed to analyze and clarify the biological function of Gossypium hirsutum GhVAS1, and to elucidate its regulatory mechanism underlying boll abscission. [Methods] Using the Arabidopsis thaliana VAS1 gene as a query sequence, two GhVAS1 homologs (GhVAS1-A05 and GhVAS1-D05) were identified and cloned from the upland cotton cultivar TM-1. Subsequently, phylogenetic analysis, conserved motif prediction and protein structure characterization of the cloned GhVAS1 genes were performed. The spatiotemporal expression patterns of GhVAS1 were analyzed by integrating RNA-sequencing (RNA-seq) data with quantitative real-time polymerase chain reaction (qRT-PCR) analysis. The subcellular localization of GhVAS1 was determined using a transient expression system in Nicotiana benthamiana. To assess the role of GhVAS1 in boll abscission, cotton leaf crumple virus (CLCrV)-mediated virus-induced gene silencing (VIGS) was employed in cotton plants. Endogenous levels of auxin (indole-3-acetic acid, IAA) and 1-aminocyclopropane-1-carboxylic acid (ACC) in abscission layer tissues were quantified, and the transcriptional profiles of abscission-related genes were analyzed. In parallel, heterologous overexpression of GhVAS1 in A. thaliana was conducted to validate its conserved regulatory role in organ abscission across plant species. [Results] Phylogenetic analysis revealed that the two GhVAS1 share a close evolutionary relationship with AtVAS1 and encode highly conserved proteins in G. hirsutum. GhVAS1 transcripts exhibited preferential accumulation in the abscission layer and were significantly and consistently upregulated in response to abscission-inducing signals. Subcellular localization assays demonstrated that both GhVAS1 proteins are localized to the nucleus and plasma membrane. VIGS-mediated silencing of GhVAS1 resulted in a significant reduction in cotton boll abscission, which was accompanied by a marked increase in endogenous IAA content and a concurrent decrease in ACC levels in abscission layer tissues. Consistently, the transcriptional levels of key ethylene biosynthetic genes (GhACS and GhACO) and cell wall hydrolysis-related genes (GhPG and GhCEL) were significantly downregulated in GhVAS1-silenced plants. In parallel, heterologous overexpression of GhVAS1 in A. thaliana accelerated floral organ abscission compared with wild-type plants. [Conclusion] GhVAS1 positively regulates boll abscission in cotton by coordinating the IAA-ethylene metabolic balance in abscission layer tissues and upregulating the expression of cell wall degradation-related genes, thereby promoting abscission layer cell separation and subsequent organ shedding.

[Objective] This study aimed to investigate the function of the GhMLO6 gene in cotton Verticillium wilt resistance and identify a candidate gene for disease resistance breeding in cotton. [Methods] Quantitative real-time polymerase chain reaction (qRT-PCR) was used to analyze the expression pattern of GhMLO6. The virus-induced gene silencing (VIGS) technique was employed to transiently silence GhMLO6 in cotton to study its function in Verticillium wilt resistance. Agrobacterium-mediated transient expression technology was applied to Nicotiana benthamiana to explore the subcellular localization of GhMLO6. [Results] The qRT-PCR results revealed that GhMLO6 presented the highest expression level in cotton roots, followed by stems and leaves. Compared with the control, infection with Verticillium dahliae significantly increased the expression level of GhMLO6 in roots. Compared with the control plants in which empty vectors were used, GhMLO6-silenced plants displayed a significant decrease in disease index and relative fungal DNA content. After stem recovery and cultivation, the accumulation of hyphae was reduced, and the resistance of cotton to Verticillium wilt was significantly increased. Transient expression analysis indicated that GhMLO6 localizes on the cell membrane. [Conclusion] GhMLO6 is localized to the cell membrane and performs a negative regulatory function in cotton Verticillium wilt resistance. Therefore materials with Verticillium wilt resistance could be obtained via gene editing technology.

[Objective] This study aims to analyze the effect of the Haloxylon ammodendron (C. A. Mey.) Bunge HaNAC12 gene on the fatty acid content and drought resistance of cotton, and to provide theoretical and technical guidance for cotton stress-resistant breeding. [Methods] The HaNAC12 gene was introduced into cotton through the cotton shoot apical meristem genetic transformation system. After molecular detection of T₀ and T₁ generation plants, the phenotypic and physiological indexes differences between transgenic and non-transgenic cotton were compared through drought stress experiments. [Results] After 30 days of natural drought stress (T30 treatment), the plant height of transgenic cotton was significantly increased by 11% compared with the non-transgenic control, and the degree of leaf wilting was less than that of the control. Physiological index analysis of cotton leaves under T30 treatment showed that the content of malondialdehyde in transgenic cotton was significantly 34% lower than that in the control, with less damage to the plasma membrane; the contents of soluble sugar, proline and chlorophyll were significantly 66%, 89% and 50% higher than those in the control, respectively, with stronger osmotic adjustment ability; the activities of superoxide, peroxidase and catalase dismutase were significantly 94%, 25% and 58% higher than those in the control, respectively, with stronger ability to scavenge reactive oxygen species. Under the T30 treatament, the expression levels of genes related to fatty acid metabolism, such as fatty acid synthase and desaturase, in transgenic cotton were significantly higher than those in the control after drought stress, and the content of free fatty acids in transgenic cotton was significantly 50% higher than that in non-transgenic cotton. There were no significant differences in leaf phenotypes and physiological and biochemical indexes between transgenic and non-transgenic cotton in the normal watering group. [Conclusion] The HaNAC12 may enhance the drought stress tolerance of cotton seedlings by promoting the synthesis and accumulation of fatty acids, providing new gene resources and material support for the genetic improvement of cotton drought resistance.

[Objective] This study aims to investigate the effects of different tillage practices combined with straw returning on cotton growth, yield, and rhizosphere soil bacterial communities in a potato-cotton rotation system, so as to provide a scientific basis for optimizing farmland management and improving soil microecological health in this system. [Methods] The cotton cultivar Xiang X1107 was used as material. Four treatments were designed: no-tillage (NT), no-tillage with straw returning (NTS), rotary tillage (T), and rotary tillage with straw returning (TS). Growth-related traits and biomass of cotton plant at key growth stages, as well as yield and its components were measured. High-throughput sequencing of the 16S rRNA gene was used to analyze the diversity and composition of rhizosphere soil bacterial communities at the boll-opening stage of cotton, and functional prediction was performed using the Functional Annotation of Prokaryotic Taxa (FAPROTAX). [Results] Straw returning and tillage practice had no significant effect on cotton emergence rate. Compared with no-tillage treatments (NT and NTS), rotary tillage treatments (T and TS) significantly increased plant height, stem diameter, and biomass at the seedling stage, and significantly increased boll weight. Whereas no significant differences in seed cotton yield and boll number were detected among all treatments. Straw returning treatments (NTS and TS) significantly elevated the Shannon Wiener's diversity index, Chao1 index, and evenness index of rhizosphere bacterial communities, with NTS showing the highest values for all indices except the Shannon Wiener's diversity index. Principal coordinates analysis (PCoA) revealed that tillage practice was the primary factor driving the differentiation of bacterial community structure. Proteobacteria was the dominant phylum across all treatments. Straw returning (NTS and TS) significantly decreased the relative abundance of Proteobacteria, while significantly increased the relative abundances of Acidobacteriota and Actinobacteriota. At the genus level, no-tillage treatments (NTS and TS) enriched nitrogen-fixing-related genera including Burkholderia_Caballeronia_Paraburkholderia, Klebsiella, Bradyrhizobium, and Allorhizobium_Neorhizobium_Pararhizobium_Rhizobium complex, and FAPROTAX prediction confirmed a significant enhancement of nitrogen fixation function. Treatment enriched Pantoea and Pseudomonas, and increased the abundances of chemoheterotrophy and human pathogen all related functional groups, whereas TS treatment effectively reduced the risk of pathogenic bacteria. [Conclusion] NTS is conducive to maintaining soil microbial diversity, enhancing nitrogen fixation function, and reducing pathogenic bacteria risk, and is thus the recommended tillage mode in the potato-cotton rotation system. TS can serve as an alternative to promote early-stage growth and regulate microbial functions. Appropriate combination modes can be selected according to local soil conditions, ecological and economic objectives in agricultural production.

[Objective] The severe shortage of freshwater has severely restricted cotton production in the arid and semi-arid areas of Xinjiang, and water deficit during the key growth stages exerts an even more adverse effect on yield. Saline water supplemental irrigation can alleviate freshwater shortages, but its optimal salinity threshold remains unclear. This study investigated the effects of supplemental irrigation with saline water of different salinity levels on the photosynthetic characteristics and yield formation of cotton, aiming to determine the suitable salinity threshold for cotton supplemental irrigation in arid areas. [Methods] A two-year field experiment was conducted during the cotton growing seasons in 2023 and 2024. The conventional fresh water without supplemental irrigation was used as the control (CK, irrigation quota of 3 600 m³·hm^-2), and five saline water supplemental irrigation treatments were established: 3.5 g·L^-1 (S3.5), 5.0 g·L^-1 (S5), 6.5 g·L^-1 (S6.5), 8.0 g·L^-1 (S8), 9.5 g·L^-1 (S9.5). The saline supplemental irrigation regime consisted of one application at the bud stage (375 m³·hm^-2) and two applications at the boll-setting stage (375 m³·hm^-2 + 450 m³·hm^-2). The total irrigation amount was 4 800 m³·hm^-2 (including 1 200 m³·hm^-2 of saline water and 3 600 m³·hm^-2 of freshwater). Gas exchange parameters, chlorophyll fluorescence parameters in functional leaves after saline water irrigations, and yield components of cotton were measured. [Results] During the early boll-setting stage, the two-year average net photosynthetic rate (P_n) of treatments with salinity levels of S3.5, S5, and S6.5 increased by 6.89%-18.00% compared with CK, and the S3.5 treatment was significantly higher than CK. The transpiration rates (T_r) of the S3.5 and S5 treatments were significantly increased by 18.96% and 9.10%, respectively, compared with CK, and the stomatal conductances (G_s) were increased by 12.95% and 3.90%, respectively. After three saline water supplementary irrigations, the initial fluorescence (F₀) of the S9.5 treatment was significantly increased by 5.99% (in 2023) and 6.54% (in 2024) relative to CK, while the maximum photochemical efficiency (F_v/F_m) of the S3.5 treatment was significantly higher than that of the S9.5 treatment. The boll-leaf ratio of cotton was the lowest in the S3.5 treatment, with two-year values of 24.58 and 24.87, followed by the S5 treatment with values of 25.02 and 25.05. The two-year average seed cotton yield of treatments with salinity levels of 3.5-6.5 g·L^-1 significantly increased by 2.73%-12.67% compared with CK (5 721.00 kg·hm^-2). [Conclusion] Supplemental irrigation with saline water with a salinity level of 3.5-6.5 g·L^-1 can optimize the photosynthetic performance of cotton and achieve stable or increased yields. However, excessively high salinity level (>6.5 g·L^-1) is prone to cause photoinhibition, leading to a significant reduction in cotton yield. This study provides an important theoretical basis for determining the salinity threshold for saline water irrigation in arid areas.

[Objective] This study aims to establish a rapid quantitative detection method for Rhizoctonia solani, the causal agent of cotton seedling damping-off in soil, and to investigate the correlation between pathogen abundance and disease occurrence, providing a scientific basis for effective disease control. [Methods] A quantitative detection method for R. solani AG-4 HGⅢ in soil was developed using internal reference strain correction and quantitative real-time polymerase chain reaction (qPCR). Pot experiments and field trials were conducted to study the relationship between R. solani abundance in soil and the incidence of cotton seedling damping-off. [Results] A qPCR-based quantitative detection method incorporating internal reference stain correction was successfully established, with high specificity and a sensitivity of 10 copies·μL^-1. The critical threshold of R. solani in soil for severe disease occurrence and seedling mortality risk was determined to be 10⁶ copies·g^-1. [Conclusion] A rapid quantitative detection method for R. solani in cotton field soil was successfully developed, enabling accurate quantification of the pathogen and the early disease risk warning.

Since its commercial release in China in 1997, transgenic Bacillus thuringiensis (Bt) cotton has fundamentally improved the control of cotton bollworm, markedly reduced chemical insecticide use, and profoundly reshaped cotton production practices in the country. However, during the initial phase of adoption, premature senescence, characterized by mid- to late-season leaf yellowing, reddening, scorching, abscission, and root functional decline, emerged as a conspicuous problem in some Bt cultivars and was initially misattributed to a direct negative effect of Bt gene insertion or constitutive Bt protein expression. More than two decades of research and field practice have made it clear that premature senescence in Bt cotton is neither a direct consequence of Bt gene insertion or Bt protein expression itself nor an inherent attribute of Bt cotton. Rather, it is a maturity imbalance driven by source-sink imbalance, root-shoot uncoupling, insufficient nutrient supply, environmental adversity, and disease pressure under specific genetic backgrounds and heavy boll load. Its physiological basis includes the photosynthetic function decline, chlorophyll degradation, reactive oxygen species accumulation, membrane lipid peroxidation, imbalanced mineral nutrient uptake and remobilization, reduced root activity, decreased cytokinin level, and enhanced abscisic acid, jasmonic acid, and ethylene signaling. At the molecular level, premature senescence involves changes in sugar transport and metabolism, hormonal signaling, reactive oxygen species-associated oxidative regulation, and the structural and functional deterioration of chloroplasts, along with senescence-related transcription factors and genes networks that coordinate chlorophyll degradation and nutrient remobilization. Systematic studies by several research groups in China have contributed to an integrated management framework involving maturity-stable cultivars, rational plant density, optimized sowing date, coordinated nitrogen and potassium supply, precise late-season nitrogen management, chemical regulation, root promotion and leaf protection, moderate sink reduction, disease resistance/tolerance, and harvest-aid coordination. This review summarizes the research trajectory of premature senescence in Bt cotton from initial controversy and conceptual correction to mechanistic integration and technical control, with emphasis on the evolution of understanding, key evidence chain, representative research progress, molecular regulatory network, integrated management strategies, and unresolved issues.

[Objective] Over the past four decades, the area of cotton planting in Shandong Province has fluctuated sharply, and significant changes have occurred in the planting regions and the structure of pests and diseases. It is necessary to clarify the characteristics of their changes and evolution in order to provide a basis for the scientific prevention and control of pests and diseases. [Methods] Based on the relevant data of National Bureau of Statistics and National Plant Protection Statistics released by National Agro-Tech Extension and Service Center, the changing trends of cotton planting area, occurrence and control of diseases and pests, and yield loss in the cotton planting region of Shandong Province were analyzed. [Results] From 1985 to 2024, the cotton planting area in Shandong Province followed a declining trajectory with pronounced fluctuations, with a trend of "rise-fall-rise-sustained-decline". And the cotton-growing areas was concentrated in the saline-alkali and infertile lands and areas lacking fresh water resources in western and northern Shandong. The total pest-disease control was larger than the occurrence area, and the control area, occurrence area, the losses averted, and the actual losses caused by pests were all higher than diseases. Ranked by the annual average occurrence area, the main pests and diseases were: Helicoverpa armigera, Aphis gossypii, seedling disease, cotton spider mites, Bemisia tabaci, cotton mirid bugs, boll disease, cotton thrips, and Fusarium wilt. The proportion of the occurrence area of cotton mirid bugs, cotton thrips, Bemisia tabaci, cotton spider mites, and boll disease showed an increasing trend, while those of A. gossypii, H. armigera, seedling disease, and Fusarium wilt decreased. The actual cotton yield loss caused by cotton mirid bugs, B. tabaci, cotton thrips, and cotton spider mites were increasing. [Conclusion] It has been clarified that the main cotton planting areas in Shandong are migrating to the saline-alkali and infertile regions in the west and north of the province. H. armigera, A. gossypii, and cotton seedling diseases were the main pests and diseases threatening cotton production. The above results provide basic data support for the prediction, early-warning and scientific prevention and control of cotton pests and diseases in this region.

[Objective] This study aims to systematically identify and characterize the composition of the adenosine diphosphate-ribosylation factor (ARF) gene family in upland cotton (Gossypium hirsutum) and to explore its potential roles in growth, development, and abiotic stress responses, thereby providing a theoretical basis for subsequent functional studies. [Methods] Based on the upland cotton reference genome, a genome-wide identification of the ARF gene family was performed, followed by analyses of phylogenetic relationships, gene structures, conserved motifs, chromosomal localization, colinearity, and cis-acting elements. Public databases and quantitative real-time polymerase chain reaction were further employed to systematically analyze the expression patterns of 42 ARF genes in different tissues, at different ovule and fiber developmental stages, and under low-temperature, high-temperature, drought, and salt stress conditions, with a comparative analysis of expression differences of Group Ⅳ members among different cultivars. [Results] A total of 42 ARF genes were identified in upland cotton and classified into four groups, with members within each group showing highly conserved gene structures and motif compositions. The ARF genes were relatively evenly distributed between the A and D subgenomes. Overall expression levels of ARF genes were obviously higher in reproductive organs than those in vegetative tissues, and most genes exhibited stage-specific high level expression during 0-5 d of ovule development and fiber development. The Group Ⅳ ARF genes showed significant expression differences among cultivars and displayed differential induction or suppression under low-temperature, salt, and drought stresses. [Conclusion] The ARF gene family in upland cotton is evolutionarily highly conserved with evidence of functional diversification. ARF genes exhibit pronounced stage-specific and functional differentiation during fiber development and abiotic stress responses, and Group Ⅳ members, together with their unique conserved motif (Motif 9), may play important regulatory roles in stress responses.

[Objective] This study aims to elucidate the potential correlation between body color polymorphism and associated bacterial community structure in Aphis gossypii. [Methods] Full-length 16S rRNA gene sequencing of bacteria from green and yellow morphs of A. gossypii was performed using the PacBio sequencing platform. Operational taxonomic unit (OTU) clustering was conducted at 97% similarity level, followed by taxonomic annotation based on the Silva database (v138.2) using Blast and Bayesian algorithms. [Results] A total of 117 bacterial OTUs were identified in both green morph and yellow morph, belonging to 9 phyla, 13 classes, 35 orders, 57 families, 89 genera, and 114 species, with notable differences in bacterial composition between the two types. The green individuals harbored a greater diversity of bacteria (9 phyla, 13 classes, 34 orders, 54 families, 80 genera, and 100 species) compared to the yellow ones (6 phyla, 9 classes, 30 orders, 47 families, 75 genera, and 97 species). The classes of Acidobacteriia, Kapabacteria, Cyanophyceae, and Desulfuromonadia were unique to the green morph, encompassing 14 exclusive genera such as Verrucomicrobiaceae and Comamonas. No unique bacterial groups at the class level were identified in the yellow morph. Significant differences in bacterial relative abundance were observed between the two morphs. For instance, the relative abundance of Enterobacter was significantly higher in the yellow morph (2.39%) than that in the green morph (1.08%). Conversely, Pantoea was significantly more abundant in the green morph (1.45%) than that in the yellow morph (0.93%). Among the unique genera of the green morph, Comamonas had the highest relative abundance (1.02%), whereas Arsenophonus was the most abundant unique genus in the yellow morph (3.43%). [Conclusion] There are significant differences in the bacterial community composition between green and yellow morphs of A. gossypii. Analyses of key characteristics, including genus-level diversity, relative abundance, and the distribution of unique genera, indicate a certain correlation between color polymorphism and bacterial community composition in the cotton aphid. This study lays a solid foundation for further investigation into the mechanisms of microbial-mediated regulation of color differentiation in A. gossypii.

[Objective] This study aims to investigate the molecular mechanism underlying the resistance of Zhongzhimian 2 to Verticillium wilt. [Methods] Roots and leaves of Zhongzhimian 2 (disease-resistant variety) and Jimian 11 (disease-susceptible variety) were collected at 48 h after inoculation with Verticillium dahliae strain Vd991, followed by freeze-drying. Non-targeted metabolomics technology was employed to analyze the differential metabolites in the roots and leaves of Zhongzhimian 2 and Jimian 11, and the differential metabolic pathways were further analyzed. [Results] Compared with Jimian 11, the abundance of tryptophan and chorismate in the roots of Zhongzhimian 2 decreased, while the abundance of 13 metabolites including salicylic acid, anthranilate, and indole increased. The abundance of 13 metabolites, including tryptophan, chorismate, and anthranilate, was upregulated in the leaves of Zhongzhimian 2, while the abundance of 10 metabolites, including salicylic acid and indole, was downregulated. These differential metabolites were primarily enriched in the biosynthesis of unsaturated fatty acids, tryptophan metabolism, the biosynthesis of phenylalanine, tyrosine, and tryptophan, and linoleic acid metabolism. Comprehensive analysis revealed that the tryptophan metabolism showed the most significant differences. Zhongzhimian 2 inhibited tryptophan synthesis by downregulating the expression levels of the tryptophan synthase genes GhTSA1 and GhTSB1, leading to the accumulation of indole and subsequently promoting salicylic acid synthesis in the roots, thereby activating root immune responses to pathogen infection and conferring resistance to Verticillium wilt. [Conclusion] This study analyzed and compared the differences in secondary metabolites between the roots and leaves of Zhongzhimian 2 and Jimian 11, elucidated the mechanism by which Zhongzhimian 2 exerts its resistance to Verticillium wilt by regulating tryptophan metabolism and provided a theoretical basis for disease-resistant breeding.

[Objective] This study aims to characterize the fiber quality traits of Gossypium hirsutum germplasm resources and to determine their genetic diversity and potential for improvement. [Methods] A panel of 180 G. hirsutum germplasm resources was planted across two experimental locations (Manas and Yuepuhu) for two consecutive cotton growing seasons. Five fiber quality-related traits were measured, and multiple statistical approaches, including genetic diversity analysis, variance analysis, correlation analysis, cluster analysis, and principal component analysis, were adopted to conduct a comprehensive evaluation of the tested germplasms. [Results] The genetic diversity index of the test materials ranged from 0.68 to 1.37. The coefficient of variation for breaking elongation was highest (15.81%) at the Yuepuhu trial site in 2025, and lowest (0.98%) at the Manas trial site in 2024. Highly significant differences (P < 0.01) in fiber quality traits were observed among both genotypes and environments for the cotton germplasm accessions tested. Introduced varieties from other breeders showed higher variation in fiber length, uniformity index, and breaking tenacity, whereas self-bred varieties by our team possessed greater variation in micronaire and breaking elongation. All fiber quality traits were significantly correlated with each other. The tested germplasms were classified into five clusters based on cluster analysis. Two principal components were extracted, with a cumulative contribution rate of 73.56%. Ultimately, ten elite accessions with superior comprehensive performance were screened according to the comprehensive D value: Jinfeng T299, Shouxin H-157, ZJL1224, Jinfeng T390, Shouxin HS-173, AW1448, ZJL1348, Zhongshengmian 21, AW1031, 1059G. [Conclusion] The tested G. hirsutum population exhibits abundant genetic diversity, and distinct phenotypic differences are observed among germplasms from different sources. The screened elite accessions can serve as outstanding parental materials, providing valuable insights for the directional improvement of fiber quality and the optimization of breeding efficiency in upland cotton.