The systemic fungicide carboxin (5,6-dihydro-2-methyl-1,4-oxathiin-3-carboxanilide) at 100 mum inhibited succinate cytochrome c reductase in mitochondria from Ustilago maydis and Saccharomyces cerevisiae. It did not have any effect on reduced nicotinamide adenine dinucleotide (NADH) cytochrome c reductase. Succinate coenzyme Q reductase was also inhibited, but NADH coenzyme Q reductase was not. When dichlorophenolindophenol (DCIP) was used as the terminal acceptor of electrons from the oxidation of succinate, carboxin was very effective in inhibiting succinate-DCIP reductase. Carboxin was inhibitory to succinic dehydrogenase assayed with phenazine methosulfate plus DCIP when intact mitochondria were used as the enzyme source but not when solubilized enzyme was used. The main site of action of carboxin, therefore, appears to lie between succinate and coenzyme Q. The dioxide analogue of carboxin was also effective in inhibiting succinate-cytochrome c reductase, succinate-coenzyme Q reductase, or succinate-DCIP reductase, whereas the monoxide analogue was less effective in inhibiting these enzymes.

【目的】研究冷胁迫条件下萎锈灵杀菌剂对棉花种子发芽率、保苗率及幼苗耐低温冷害胁迫能力的影响,为萎锈灵杀菌剂应用于棉花生产提供依据。【方法】在室内制备5种不同浓度(4.2%、5.7%、7.2%,8.7%和10.2%)的萎锈灵,以裸种子不包衣处理作为空白对照,以基础杀菌剂包衣处理作为参比对照,按药种比1∶100进行种子包衣处理,测定在冷胁迫条件下萎锈灵杀菌剂对棉种的发芽率、出苗率、保苗率、棉苗株高、叶片数、干鲜重和光合参数,并采用主成分分析法,综合评价萎锈灵对棉花耐低温胁迫的影响。【结果】8.7%萎锈灵处理的种子发芽率较空白对照分别增加7.0%(25℃)、12.0%(18℃)、18.0%(15℃)和20.5%(12℃),较参比对照分别增加5.0%(25℃)、9.0%(18℃)、12.0%(15℃)和16.4%(12℃)。7.2%萎锈灵处理的出苗率较空白对照增加10.1%,较参比对照增加13.0%、8.7%萎锈灵处理的保苗率较空白对照增加9.1%,较参比对照增加13.2%。7.2%萎锈灵处理的幼苗株高、茎粗、鲜重和干重分别较空白对照增加8.9%、9.7%、7.4%和25.4%,较参比对照分别增加10.8%、10.7%、8.3%和27.5%。7.2%萎锈灵处理提高了在冷胁迫条件下的棉花幼苗叶片净光合速率、气孔导度、胞间CO₂浓度指标,较空白对照分别增加11.0%、17.0%和9.0%,较参比对照分别增加6.0%、6.0%和5.0%,这些指标差异均达显著水平。7.2%萎锈灵杀菌剂处理增强棉花耐低温冷害胁迫能力的作用效果最好,其次为8.7%萎锈灵杀菌剂。【结论】萎锈灵杀菌剂处理能够增强棉花种子活力,提高了发芽率、出苗率和保苗效果,提高了棉苗耐低温冷害胁迫能力,可促进棉苗光合作用和生长。

【Objective】 To study the effect of carhoxin Fungicide on the germination and seedling of cotton under chilling stress, the Optimum concentration to improve the germination rate, seedling preservation rate and seedling chilling tolerance were explored in the hope of providing theoretical basis and technical support for the application of seed film coating carhoxin Fungicide in cotton production.【Methods】 Five kinds of seed coating agents with different concentrations (4.2%, 5.7%, 7.2%, 8.7% and 10.2%) of carhoxin were prepared in the laboratory. The naked seeds as control and the basic seed coating as control reference, and the seed coating treatment was carried out according to the drug/seed ratio of 1:100; Under the chilling stress, the germination rate and other characters were investigated and the synthetic effects were evaluated by principal component analysis through the data of the germination rate, etc.【Results】 Compared with the control, the germination rate of seeds treated with 8.7% carhoxin increased by 7.0% (25℃), 12.0% (18℃), 18.0% (15℃), 20.5% (12℃), respectively. Compared with the control reference, the germination rate of seeds treated with 7.2% carhoxin increased by 5.0% (25℃), 9.0% (18℃), 12.0% (15℃), 16.4% (12℃), respectively. The seedling rate of seeds treated with 7.2% carhoxin increased by 10.1% compared with the control, 13.0% compared with the reference. The seedling rate of seeds treated with 8.7% carhoxin increased by 9.1% compared with the control, 13.2% compared with the control reference. Compared with the control, the seedling height, stem diameter, fresh weight and dry weight of seeds treated with 7.2% carhoxin increased by 8.9%, 9.7%, 7.4% and 25.4%, respectively. Compared with the control reference, these indicators increased by 10.8%, 10.7%, 8.3% and 7.5%, respectively. Compared with the control, the indexes of net photosynthetic rate, stomatal conductance and intercellular CO₂ concentration of cotton seedling leaves of seeds treated with 7.2% carhoxin under chilling stress increased by 11.0%, 17.0% and 9.0%, respectively. Compared with the control reference, these indicators increased by 6.0%, 6.0% and 5.0%, respectively. Comprehensive analysis showed that seed treated with 7.2% carhoxin had the optimum effect on enhancing the ability of cotton to resist chilling stress, followed by 8.7% carhoxin.【Conclusion】 The carhoxin fungicide can enhance the vigor of cotton seed, increase the germination rate, emergence rate and seedling protection effect, improve the ability of cotton seedling to withstand chilling stress, and promote the photosynthesis and growth of cotton seedling.

(1) Background: Upland cotton (Gossypium hirsutum L.) is the most important natural fiber worldwide, and it is extensively planted and plentifully used in the textile industry. Major cotton planting regions are frequently affected by abiotic stress, especially drought stress. Drought resistance is a complex, quantitative trait. A genome-wide association study (GWAS) constitutes an efficient method for dissecting the genetic architecture of complex traits. In this study, the drought resistance of a population of 316 upland cotton accessions was studied via GWAS. (2) Methods: GWAS methodology was employed to identify relationships between molecular markers or candidate genes and phenotypes of interest. (3) Results: A total of 8, 3, and 6 SNPs were associated with the euphylla wilting score (EWS), cotyledon wilting score (CWS), and leaf temperature (LT), respectively, based on a general linear model and a factored spectrally transformed linear mixed model. For these traits, 7 QTLs were found, of which 2 each were located on chromosomes A05, A11, and D03, and of which 1 was located on chromosome A01. Importantly, in the candidate regions WRKY70, GhCIPK6, SnRK2.6, and NET1A, which are involved in the response to abscisic acid (ABA), the mitogen-activated protein kinase (MAPK) signaling pathway and the calcium transduction pathway were identified in upland cotton at the seedling stage under drought stress according to annotation information and linkage disequilibrium (LD) block analysis. Moreover, RNA sequencing analysis showed that WRKY70, GhCIPK6, SnRK2.6, and NET1A were induced by drought stress, and the expression of these genes was significantly different between normal and drought stress conditions. (4) Conclusions: The present study should provide some genomic resources for drought resistance in upland cotton. Moreover, the germplasm of the different phenotypes, the detected SNPs and, the potential candidate genes will be helpful for molecular marker-assisted breeding studies about increased drought resistance in upland cotton.

【目的】通过系统调查TM-1农艺性状及纤维品质,研究芽期和苗期的耐冷性,以及对其在低温胁迫条件下的耐冷相关基因进行实时荧光定量分析,深入挖掘其耐冷机理,为该种质利用提供理论依据。【方法】在田间,以中棉所35为对照,以人工调查方式对TM-1进行表型鉴定,依据国际校准棉花标准（HVICC）测定纤维品质,同时采用卡那霉素筛选和分子鉴定进行Bt检测。以抗冷品种豫2067和冷敏感品种衡棉3号为对照,对TM-1芽期和子叶期进行耐冷性鉴定,4℃低温处理,然后正常条件下恢复生长7 d,调查芽期相对子叶平展率及子叶期植株受胁迫后的冷害级别,计算冷害指数和耐冷指数;使用便携式叶绿素仪进行叶片活体测定,以SPAD值代表相对叶绿素含量;在三叶期进行4℃低温处理24 h,利用实时荧光定量方法进行耐冷相关基因在叶片中的表达测定。【结果】表型鉴定结果显示,TM-1叶片较大,颜色深绿,生育期较长,约135 d,霜前籽棉产量为2 791.50 kg·hm^-2,株高94.60 cm,霜前籽棉产量、株高、单株果枝数和单株结铃数均高于中棉所35,其他农艺性状与中棉所35接近,纤维品质中等水平。卡那霉素和试纸检测结果表明TM-1与中棉所35均不含Bt。芽期耐冷性鉴定结果表明,与对照处理相比,TM-1叶片的相对叶绿素含量极显著下降,株高极显著降低,低温胁迫极显著抑制了棉花下胚轴的伸长,并且抑制了叶片叶绿素的合成;低温处理后,TM-1的主根受到了伤害,恢复生长后侧根却比较发达,侧根生长优于对照。TM-1芽期耐冷级别达到高抗冷。苗期抗冷性鉴定结果表明,与对照相比,TM-1的相对叶绿素含量显著下降,株高极显著降低。TM-1子叶期耐冷指数为85.32%,显著高于抗冷材料豫2067,耐冷级别达到抗冷。TM-1三叶期受低温胁迫24 h后,在叶片中,有9个耐冷相关基因上调表达,上调表达倍数显著或极显著高于衡棉3号;其中,脱水素基因在叶片中上调表达,表达倍数与其在豫2067叶片中的表达倍数相近,是衡棉3号叶片中表达倍数的4.69倍,LEA3在TM-1叶片中的上调表达倍数显著高于豫2067和衡棉3号。总之,TM-1属于中晚熟品系,纤维品质中等,不含Bt;芽期和子叶期均比较抗冷,属于比较抗冷的类型;与耐冷相关的基因在TM-1的叶片中受低温诱导表达,拥有特别的表达模式。【结论】TM-1具有稳定的农艺性状,纤维品质达中等水平,不含Bt,可用作转外源基因的良好受体;因为其良好的耐冷特性,TM-1可以作为棉花耐冷性育种改良的重要亲本来源和基因克隆的基因源。

【Objective】We systematically investigated the major agronomic traits and cold tolerance of accession TM-1 at the bud and seedling stages. The relative expressions of cold tolerance-related genes were analyzed by the qRT-PCR method. The cold tolerance mechanism of TM-1 was further discussed, which provides the theoretical basis for the breeding utilization of TM-1.【Method】The major agronomic traits of TM-1 were manually investigated in the field using variety CRI35 as the control. The fiber quality was assessed by an international calibrated cotton standard (HVICC), and the insect resistance (Bt) was detected by kanamycin screening and molecular detection technologies. For the cold tolerance testing, two contrasting accessions, cold-resistant accession Yu 2067 and cold-sensitive variety Hengmian 3 were set as controls, respectively. The cold resistance of TM-1 at bud stage and cotyledon stage was identified, treated at 4℃ and then recovered under normal conditions for 7 days, and the relative cotyledon spreading rate and the cold injury levels of plants were investigated, and cold injury indexes and cold resistance indexes were calculated. The portable chlorophyll meter was used for in vivo testing the leaf relative chlorophyll content (represented by SPAD value). The expressions of cold tolerance-related genes in leaves were measured by qRT-PCR method. 【Result】 The leaves of TM-1 were large and dark green. The pre-frost seed cotton yield was 2 791.50 kg·hm-2, and the plant height was 94.60 cm. The growth period was about 135 days, and the yield, plant height, fruit branch number per plant, boll number per plant were higher than CRI35, while other agronomic traits were similar to CRI35. TM-1 had medium fiber quality. The test results of kanamycin and test paper showed that TM-1 did not contain the Bt like CRI35. Identification results of cold tolerance at bud stage showed that compared with the control treatment, the relative chlorophyll content and plant height of TM-1 decreased significantly. Low-temperature stress significantly inhibited hypocotyl elongation and chlorophyll synthesis in cotton leaves. Under low-temperature treatment, the taproots of TM-1 were damaged, but the lateral roots were more developed than those of the control. The cold tolerance level of TM-1 reached high cold resistance at the bud stage. Identification of cold tolerance at the cotyledon stage showed that the relative chlorophyll content and plant height of TM-1 decreased significantly compared with the control. The cold tolerance index of TM-1 at the cotyledon stage was 85.32%, which was significantly higher than Yu 2067, and the tolerance level of TM-1 reached cold resistance at the cotyledon stage. After the treatment of low-temperature stress for 24 h at the trefoil stage, nine genes were up-regulated in the TM-1 leaves, and their up-regulated expression folds were significantly higher than those of cold-sensitive accession. Dehydrin gene was up-regulated in TM-1 leaves, and the expression fold was similar to that in the leaves of Yu 2067, which was 4.69 times that in the leaves of Hengmian 3. The expression fold of the LEA3 gene in TM-1 leaves was significantly higher than that of Yu 2067 and Hengmian 3. 【Conclusion】 Accession TM-1 has stable agronomic characters and the medium fiber quality. It can be used as an ideal receptor for transferring exotic genes because without Bt. TM-1 can also be used as an important parent for cotton breeding and a gene source for cloning genes because of its good cold tolerance.

通过室内砂培试验，研究了不同浓度水杨酸包衣剂包衣棉种对棉花幼苗抗寒性的影响，分析了棉花幼苗低温胁迫前后以及恢复常温叶片细胞膜透性、抗氧化物酶及渗透调节物质对水杨酸包衣剂包衣的生理响应。结果表明：1～10 mmol·L^－1的水杨酸包衣剂包衣处理，能有效减轻低温对棉花幼苗的伤害。棉花幼苗叶片的相对电导率(REC)和丙二醛(MDA)的积累量显著降低，超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)等抗氧化保护酶的活性显著增强，可溶性蛋白、可溶性糖、游离脯氨酸等渗透调节物质的含量显著提高。说明水杨酸包衣剂包衣处理能缓解低温胁迫对幼苗生长的抑制，提高棉花幼苗的抗寒性，并以5 mmol·L^－1的水杨酸包衣效果最好。