Combining ability of Egyptian cotton(Gossypium barbadense L.)reveals genetic potential for improved yield and fiber quality

Background As the most widely cultivated fiber crop,cotton production depends on hybridization to unlock the yield potential of current varieties.A deep understanding of genetic dissection is crucial for the cultivation of enhanced hybrid plants with desired traits,such as high yield and fine fiber quality.In this study,the general combining ability(GCA)and specific combining ability(SCA)of yield and fiber quality of nine cotton parents(six lines and three testers)and eighteen F1 crosses produced using a line×tester mating design were analyzed.Results The results revealed significant effects of genotypes,parents,crosses,and interactions between parents and crosses for most of the studied traits.Moreover,the effects of both additive and non-additive gene actions played a notably significant role in the inheritance of most of the yield and fiber quality attributes.The F1 hybrids of(Giza 90×Aust)×Giza 86,Uzbekistan 1×Giza 97,and Giza 96×Giza 97 demonstrated superior performance due to their favorable integration of high yield attributes and premium fiber quality characteristics.Path analysis revealed that lint yield has the highest positive direct effect on seed cotton yield,while lint percentage showed the highest negative direct effect on seed cotton yield.Principal component analysis identified specific parents and hybrids associated with higher cotton yield,fiber quality,and other agronomic traits.Conclusion This study provides insights into identifying potential single-and three-way cross hybrids with superior cotton yield and fiber quality characteristics,laying a foundation for future research on improving fiber quality in cotton.

外源添加L-脯氨酸对棉花黄萎病发生及其根际土壤微生物群落的影响

【目的】根系分泌物是植物与土壤微生物进行互作的信号媒介,对于植物病害发生和植株生长均具有重要调控功能。论文旨在明确棉花根系分泌物L-脯氨酸抵御棉花黄萎病发生的微生态机制,揭示L-脯氨酸介导的根际微生物与棉花黄萎病发生的互作关系,为构建生物防治土传病害的有益菌群提供新视角。【方法】通过温室盆栽试验,以外源添加不同浓度的L-脯氨酸(0、50、100、200和400 mmol·L^(-1))为试验处理,采用实时荧光定量PCR(real-time qPCR)和宏基因组测序技术分别测定不同处理的土壤中大丽轮枝菌(Verticillium dahliae)DNA拷贝数量和土壤微生物群落结构及功能,采用主成分分析比较不同处理的根际土壤微生物群落结构,利用冗余分析研究土壤养分因子与微生物群落结构的相关性,利用斯皮尔曼相关分析研究微生物群落结构功能代谢途径的相关性。【结果】与空白对照相比,低浓度(50 mmol·L^(-1))L-脯氨酸处理不能够减轻棉花黄萎病的发生,高浓度(100、200和400 mmol·L^(-1))L-脯氨酸处理的病情指数分别下降22.51%、60.23%和64.23%。qPCR结果表明,L-脯氨酸处理不能够显著降低土壤中大丽轮枝菌拷贝数量。宏基因组测序分析表明,L-脯氨酸处理后细菌多样性Shannon指数显著增加,真菌多样性Shannon指数呈下降趋势。在属水平上,L-脯氨酸处理后类诺卡氏菌属(Nocardioides)、溶杆菌属(Lysobacter)、节杆菌属(Arthrobacter)、Phycicoccus、假单胞菌属(Pseudomonas)和毛霉菌属(Mucor)的相对丰度呈上升趋势。线性判别分析表明,除浓度为100 mmol·L^(-1)的L-脯氨酸外,外源添加L-脯氨酸处理后根际土壤微生物KEGG通路的富集情况发生改变。冗余分析表明,细菌群落组成受pH、电导率、硝态氮、铵态氮和有机质显著影响,而真菌群落组成与铵态氮存在显著相关性。Spearman相关分析表明,细菌的KEGG代谢通路与pH、有机质、铵态氮含量呈负相关关系,而与电导率和硝态氮呈正相关关系;真菌的大部分KEGG代谢通路与土壤养分的相关性较差。【结论】外源添加适量L-脯氨酸通过改变土壤细菌群落结构和功能,增加有益微生物的相对丰度,从而影响棉花黄萎病的发生,但其不能够改变病原菌数量。同时,根际细菌群落组成和功能均与土壤养分存在相关性。

Comparative Transcriptome Analysis of Seed Germination of a Cotton Variety with High Tolerance to Low Temperature

Gossypium hirsutum L.is an important cash crop native to the subtropics and is widely cultivated around the world.Low temperature is an important stress that seriously affects seed germination and emergence during planting.In this study,transcriptomic profiles of low-temperature-and normal-temperature-germinated seeds of Xinluzao 25,a variety with low-temperature tolerance and high germination rates,were analyzed and compared.The following results were obtained.(1)A total of 81.06 Gb of clean data were obtained after transcriptome sequencing and assembly,and 76,931 non-redundant Unigene sequences were obtained after data consolidation and concatenation;of these,69,883 Unigene sequences were annotated.In addition,55,463 Unigene transcript sequences(72.2%)were annotated for Gene Ontology(GO)classification,and 26,629 genes were involved in 50 metabolic pathways identified by Kyoto Encyclopedia of Genes and Genomes(KEGG)analysis.(2)Three main pathways related to low-temperature tolerance of seed germination were identified:starch and sucrose metabolism,phenylpropanoid biosynthesis,and cysteine and methionine metabolism.Their main molecular functions involve the regulation of abscisic acid and activities of enzymes such as amylase,peroxidase,and oxidoreductase.During germination at low temperature,more genes were down-regulated than up-regulated genes at the protrusion stage(2 mm),and more genes were up-regulated than down-regulated at the germination stage(30 mm)after protrusion.(3)The enzyme activities at the two stages showed that amylase,peroxidase,catalase,and glutathione reductase had higher activities when the seeds germinated at 15℃.In this study,high expression of amylase,peroxidase,catalase,and glutathione reductase genes may be the main cause of increased tolerance to low temperature.

Evolution of Main Characteristics of the Registered Cotton Cultivars in National Cotton Regional Trials in Yangtze River Valley

[Objective] The aim of this study was to characterize the national regis- tered varieties selected from cotton regional trials in Yangtze River Valley （YaRV） in recent years. [Method] Cotton cultivar classification and comprehensive evaluation index were set up based on national cotton registration standard. GGE biplot method was adopted to analyze the correlation of major breeding target characters of 53 national registered cotton varieties in cotton regional trials in YaRV during 1981-2012. According to the shift of check cultivars in cotton regional trials in the past, the cotton regional trial practice since 1981 was divided into five periods. The dynamic of cultivar type＇s proportion and the evaluation index scores was analyzed across the five periods. [Result] There existed intricate interrelationship among cotton breeding target traits, which constrained it necessary to construct indices for com- prehensive evaluation of cotton varieties. The dynamic of cultivar types in the five periods indicated that type II varieties emerged since Simian 3 period and then its proportion decreased gradually; type Ⅲ varieties maintained a certain proportion in each period and kept on the rise overall; type Ⅳvarieties occupied the majority pro- portion of registered cultivars before 1993, but a minor proportion since Simian 3 period. On the other side, the change trend of the evaluation index demonstrated that the varieties registered before 2003 did not pass the qualified line at present. The peak scores appeared in the varieties registered during 2004-2008. The scores of the varieties registered after 2009 were only slightly over the qualified line. [Conclusion] More attention should be paid to the improvement and evaluation of micronaire, so as to guide the simultaneous development of high yielding and fiber quality in cotton breeding and registration procedure in YaRV.

Comparison of Biochemical Substances in the Fiber Development of Different Cotton Varieties

Zhongmian 42 and Xinluzao 36 were used as raw materials to determine the contents of soluble sugar and protein, as well as dynamic changes of enzyme activities after flowering during cotton fiber growth. The results showed that contents of soluble protein in the two species sharply declined 7 to 21 days after flowering, as the soluble sugar in Zhongmian 42 leveling off after 21 days of flowering while the soluble sugar in Xinluzao 36 dropped notably after 21 days of flowering before remaining stable after seven days later. The soluble sugar decreased 7 to 14 days after flowering before sharply rising to the maximum seven days later, and then began to decline quickly. The soluble sugar was the minimum after 35 days of flowering and then remaining stable. Peroxidase activity generally increased. Indole-3- acetic acid oxidase activities were low at 7 days after flowering. IAAO activity reached to the peaks on the 14th and 28th day after flowering. IAAO activity of two varieties decreased with the same trend 35 days after flowering.

Screening of drought resistance indices and evaluation of drought resistance in cotton(Gossypium hirsutum L.)

Sixteen cotton cultivars widely planted in China were sowed under five different drought concentrations(0,2.5,5,7.5,and 10%)using PEG6000 to screen the indices of drought resistance identification and explore the drought resistance of different cotton cultivars.Eighteen physiological indices including root,stem,and leaf water contents(RWC,SWC,and LWC),net photosynthetic rate(Pn),the maximum photochemical quantum yield(Fv/Fm),the actual photochemical quantum yield(ΦPSII),non-photochemical quenching coefficient(NPQ),leaf water potential(LWP),osmotic potential(Ψs),leaf relative conductivity(REC),leaf proline content(Pro),leaf and root soluble protein contents(LSPC and RSPC),leaf and root malondialdehyde(MDA)contents(LMDA and RMDA),root superoxide dismutase,peroxidase,and catalase activities(RSOD,RPOD,and RCAT)were measured.Results indicated the 18 physiological indices can be converted into five or six independent comprehensive indices by principal component analysis,and nine typical indices(Fv/Fm,SWC,LWP,Pro,LMDA,RSPC,RMDA,RSOD,and RCAT)screened out by a stepwise regression method could be utilized to evaluate the drought resistance.Moreover,the 16 cotton cultivars were divided into four types:drought sensitive,drought weak sensitive,moderate drought resistant,and drought resistant types.The resistance ability of two selected cotton cultivars(drought resistant cultivar,Dexiamian 1;drought sensitive cultivar,Yuzaomian 9110)with contrasting drought sensitivities were further verified by pot experiment.Results showed that the responses of final cotton biomass,yield,and yield composition to drought were significantly different between the two cultivars.In conclusion,drought resistant cultivar Dexiamian 1 and drought sensitive cultivar Yuzaomian 9110 were screened through hydroponics experiment,which can be used as ideal experimental materials to study the mechanism of different cotton cultivars with contrasting drought sensitivities in response to drought stress.

Effects of Soil Water Content on Cotton Root Growth and Distribution Under Mulched Drip Irrigation

The relation between soil water content and the growth of cotton root was studied for the scheme of field water and cotton yield under mulched drip irrigation. Based on the field experiments, three treatments of soil water content were conducted with 90%, 75%θf, and 60%θf （θfis field water capacity）. Cotton roots and root-shoot ratio were studied with digging method, and the soil moisture was observed with TDR （time domain reflector）, and cotton yield was measured. The results indicated that the growth of cotton root accorded with Logistic growth curve in the three treatments, the cotton root grew quickly and its weight was very high under 75%θf because of the suitable soil water condition, while grew slowly and its weight was lower under 90%θf due to water moisture beyond the suitable condition, and the root weight was in between under 60%θf For the three water treatments, the cotton root weight decreased with soil depth, and decreased more significantly in deeper soil layer with the soil moisture increasing. And the ratio of cotton root weight in 0-30 cm soil layer to the total root weight was the highest under 75%θf. The cotton root system was distributed mainly in the soil of narrow row and wide row mulched with plastic film, and little in the soil outside plastic film. The weight of cotton root was the highest in the soil of narrow row or wide row mulched with plastic film under 75%θf. Root-shoot ratio decreased with the soil moisture increasing. The soil water content affected cotton yields, and cotton yield was the highest under 75%θf. The higher soil moisture level is unfavorable to the growth of cotton root system and yield of cotton under mulched drip irrigation.

Effect of N fertilization rate on soil alkalihydrolyzable N, subtending leaf N concentration,fiber yield, and quality of cotton

Soil alkali-hydrolyzable nitrogen, which is sensitive to N fertilization rate, is one of the indicators of soil nitrogen supplying capacity. Two field experiments were conducted in Dongtai(120°19″ E, 32°52″ N), Jiangsu, China in 2009 and Dafeng(120°28″ E, 33°12″ N), Jiangsu province, China in 2010. Six nitrogen rates(0, 150, 300, 375, 450, and 600 kg ha^(-1)) were used to study the effect of N fertilization rate on soil alkali-hydrolyzable nitrogen content(SAHNC), subtending leaf nitrogen concentration(SLNC), yield, and fiber quality. In both Dongtai and Dafeng experiment station, the highest yield(1709 kg ha^(-1)), best quality(fiber length 30.6 mm, fiber strength 31.6 c N tex^(-1), micronaire 4.82), and highest N agronomic efficiency(2.03 kg kg^(-1)) were achieved at the nitrogen fertilization rate of 375 kg ha^(-1). The dynamics of SAHNC and SLNC could be simulated with a cubic and an exponential function,respectively. The changes in SAHNC were consistent with the changes in SLNC. Optimal average rate(0.276 mg day^(-1)) and duration(51.8 days) of SAHNC rapid decline were similar to the values obtained at the nitrogen rate of 375 kg ha^(-1)at which cotton showed highest fiber yield, quality, and N agronomic efficiency. Thus, the levels and strategies of nitrogen fertilization can affect SAHNC dynamics. The N fertilization rate that optimizes soil alkali-hydrolyzable nitrogen content would optimize the subtending leaf nitrogen concentration and thereby increase the yield and quality of the cotton fiber.

Multi-Location Investigation of Optimum Planting Density and Boll Distribution of High-Yielding Cotton (G.hirsutum L.) in Hubei Province,China

Cotton yield per unit ground area has stagnated for a dozen years in Hubei Province, China, although a series of new high- yielding varieties have been commercialized. A multi-location investigation was carried out in 2008 and 2009 in 13 counties to determine if increased planting population density （PPD） would break the stagnant yield. The results showed that significant differences among the fields existed in theoretical yield, PPD, and bolls per square meter （BPM）. The lowest yield of 1 641.1 kg ha-I was resulted from the lowest PPD of 1.7 plants m-2 and the lowest BPM of 71.8 bolls m-2, while the highest yield of 2 779.7 kg ha-~ was resulted from the highest PPD of 2.5 plants m-2, and the highest BPM of 129.4 bolls m-z. Plant mapping revealed that boll retention rate （BRR） was maintained over 30 or 40% for the first 17-18 fruiting branches （FBs） and decreased dramatically thereafter, rotten boll rate （RBR） decreased, but open boll rate （OBR） rose first and dropped later with rising FB from the bottom to the top. But BRR, RBR, and OBR were all dropped with the fruiting positions （FPs） extending outwards. The optimum range of plant density would be 2-3 plants m-2 and the proper individual plant structure would be 16-19 FBs with 5-7 FPs for cotton production in Hubei Province.

Relationship between plant canopy characteristics and photosynthetic productivity in diverse cultivars of cotton(Gossypium hirsutum L.)

Genotype and plant type affect photosynthetic production by changing the canopy structure in crops.To analyze the mechanism of action of heterosis and plant type on canopy structure in cotton(Gossypium hirsutum L.),we had selected two cotton hybrids(Shiza 2,Xinluzao 43) and two conventional varieties(Xinluzao 13,Xinluzao 33) with different plant types in this experiment.We studied canopy characteristics and their correlation with photosynthesis in populations of different genotypes and plant types during yield formation in Xinjiang,China.Canopy characteristics including leaf area index(LAI),mean foliage tilt angle(MTA),canopy openness(DIFN),and chlorophyll relative content(SPAD).The results showed that LAI and SPAD peak values were higher and their peak values arrived later,and the adjustment capacity of MTA during the flowering and boll-forming stages was stronger in Xinluzao 43,with the normal-leaf,pagoda plant type,than these values in other varieties.DIFN of Xinluzao 43 remained between0.09 and 0.12 during the flowering and boll-forming stages,but was lower than that in the other varieties during the boll-opening stage.Thus,these characteristics of Xinluzao 43 were helpful for optimizing the light environment and maximizing light interception,thereby increasing photosynthetic capability.The photosynthetic rate and photosynthetic area were thus affected by cotton genotype as changes in the adjustment range of MTA,increases in peak values of LAI and SPAD,and extension of the functional stage of leaves.Available photosynthetic area and canopy light environment were affected by cotton plant type as changes in MTA and DIFN.Heterosis expression and plant type development were coordinated during different growth stages,the key to optimizing the canopy structure and further increasing yield.

Plant Growth,Yield Components,Economic Responses,and Soil Indigenous K Uptake of Two Cotton Genotypes with Different K-Efficiencies

HG103,a high K-efficiency cotton cultivar with high-yield potential,and LG122,a low K-efficiency cotton cultivar with low-yield potential were used to study the genotypic variation on yield,economic responses,and soil indigenous K exploitation for cotton in pot and field conditions in 2006 and 2007.Results indicated that both the cultivars differed significantly in the rate of translocation of dry matter into reproductive organs and the time of running into reproductive stage.Cotton yield and economic parameters of HG103 were much better than LG122.Potassium content in cotton shells reached the highest level at maturity stage for both genotypes.Results also showed that the K content in each plant part of HG103 was lower than that of LG122.The two genotypes showed different efficiencies and abilities on absorbing soil rapidly available K and slowly available K.LG122 showed higher absorption of K rate than HG103 after K fertilization,but on the contrary,HG103 uptake more soil indigenous K than LG122 in no K fertilization treatment.This result indicated that HG103 could tolerant and absorb more soil indigenous K than LG122,under condition of soil K stress.LG122 could grow well and absorb more K nutrient when soil K supply is sufficient.Our results demonstrated that higher K content in plant tissues and higher K uptake by plant may not an exclusive condition for high yield planting with K fertilization.Earlier translocation of more dry matters into reproductive organs is one of the key mechanisms of high K use efficiency in cotton.

Development of glyphosate-tolerant transgenic cotton plants harboring the G2-aroA gene

Given that glyphosate weed control is an effective strategy to reduce costs and improve economic outcomes of agricultural production in China,the development of glyphosate-resistant cotton holds great promise.Using an Agrobacterium-mediated transformation method,a new G2-aroA gene that encodes 5-enolpyruvylshikimate-3-phosphate synthase（EPSPS）was transformed into cotton cultivar K312.The transgenic cotton plants were regenerated from a callus tissue culture via kanamycin selection.Ten regenerated cotton plants were obtained and allowed to flower normally to produce fruit.The results from polymerase chain reaction（PCR）and Southern and Western blot analyses indicated that the target gene was integrated into the cotton chromosome and was expressed effectively at the protein level.The glyphosate tolerance analysis showed that the transgenic cotton had a high resistance to glyphosate.Further,even cotton treated with 45.0 mmol L^–1 of glyphosate was able to slowly grow,bloom and seed.The transgenic cotton may be used for cotton breeding research of glyphosate-tolerant cotton.

Relationships between temperature-light meteorological factors and seedcotton biomass per boll at different boll positions

Cotton growth and development are determined and influenced by cultivars, meteorological conditions, and management practices. The objective of this study was to quantify the optimum of temperature-light meteorological factors for seedcotton biomass per boll with respect to boll positions. Field experiments were conducted using two cultivars of Kemian 1 and Sumian 15 with three planting dates of 25 April （mean daily temperature （MDT） was 28.0 and 25.4°C in 2010 and 2011, respectively）, 25 May （MDT was 22.5 and 21.2°C in 2010 and 2011, respectively）, and 10 Jun （MDT was 18.7 and 17.9°C in 2010 and 2011, respectively）, and under three shading levels （crop relative light rates （CRLR） were 100, 80, and 60％） during 2010 and 2011 cotton boll development period （from anthesis to boll open stages）. The main meteorological factors （temperature and light） affected seedcotton biomass per boll differently among different boll positions and cultivars. Mean daily radiation （MDR） affected seedcotton biomass per boll at all boll positions, except fruiting branch 2 （FB2） fruting node 1 （FN1）. However, its influence was less than temperature factors, especially growing degree-days （GDD）. Optimum mean daily maximum temperature （MDTmax） for seedcotton biomass per boll at FB11FN3 was 29.9-32.4°C, and the optimum MDR at aforementioned position was 15.8-17.5 MJ m-2. Definitely, these results can contribute to future cultural practices such as rational cultivars choice and distribution, simplifying field managements and mechanization to acquire more efficient and economical cotton management.

Characterization of Gh SERK2 and its expression associated with somatic embryogenesis and hormones level in Upland cotton

Somatic embryogenesis （SE） is one of the most important steps during regeneration of cotton, but the molecular mechanism of SE remains unclear. SOMATIC EMBRYOGENSIS RECEPTOR KINASE （SERK） gene is known to function in SE. A homolog GhSERK2 （accession number： JF430801） was cloned from Upland cotton and characterized for its functions in SE. GhSERK2 expressed in different tissues and showed higher expression level in floral organs than vegetative ones with the highest levels in ovule and anther. GhSERK2 expressed during SE with a high level at globular embryos stage. Upon treatment with indole-3-butytic acid （IBA）, the transcription level of GhSERK2 was induced and promoted SE subsequently. A 2-day treatment of 2,4-dichlorophenoxyacetic acid （2,4-D） induced the expression of GhSERK2, but treatments of 2,4-D for longer periods sharply inhibited the GhSERK2 transcription level of embryogenic callus （EC）. The levels of hormones, including 3-indoleacetic acid （IAA）, abscisic acid （ABA）, and brassinosteroid （BR）, were increased in the initial calli induced from the over-expression of GhSERK2 cotton. Our results indicated that GhSERK2 expression was associated with induction of SE and closely related to hormone levels during tissue culture in Upland cotton, and the gene might play an important role in regeneration of cotton.

Identification of Organic Substances Associated with Tissue Senescence in Upland Cotton (Gossypium spp. L.) Based on GC-MS Analysis

Premature senescence in crop production,especially occurred at the late growth stage,generally results in a reduction in yield and quality.Therefore,it is beneficial for yield and quality to properly delay senescence of plant tissues during the late developmental stage.In this study,it was observed that the chlorophyll content and photosynthetic rate were gradually decreased along leaf growth progression,and the rates of reduction were promoted by drought.Based on gas chromatography-mass spectrometry （GC-MS） analysis,total eight,five,seven,and five kinds of organic compounds that putatively associated with the tissue senescent progression were identified in leaves,fruit branches,petals,and sepals,respectively.It was found that the identified organic compound,such as a-pinene,b-pinene,and pentadecane were present in different tissues.Among the total ten organic substances identified to be related with the leaf senescence,half were specifically detected in the drought treatment.These results suggest some biochemical pathways associated with the leaf senescence are distinctly regulated by drought.The identified organic compounds in the tested tissues showed three types on the performance pattern based on the contents along with the senescent progression,including gradually increasing,decreasing,and a curve with one single peak.Thus,during the senescence process in tissues,a subset of metabolic substances occur modifications on the quantities,reflecting a complicate biochemical reactions are initiated via the senescence signals.Further analysis of the important organic substances will be helpful for elucidation of the tissue senescence mechanism at the biochemical level and provide a new insight of the senescence signaling transductions in cotton.

Comparative Analysis of Salinity-Induced Proteomic Changes in Cotton (Gossypium hirsutum L.)

Salt stress on cotton varieties of distinct salinity tolerance can induce expression of different proteins. Zhong 07, a salt-tolerant variety and Zhong s9612, a salt-sensitive variety, were utilized as experimental materials. The leaves of trefoil seedlings treated with or without 0.4% NaCl for 24 h were harvested for whole-protein extraction. Two-dimensional technology, combined with mass spectroscopy (MS) analysis and protein database searching, was employed to detect differentially expressed proteins and determine their identities and biological functions. Compared with the control, Zhong 07 showed 10 differentially expressed proteins under salt stress, of which 6 were upregulated and 4 were downregulated. Meanwhile, 12 differentially expressed proteins were detected in Zhong s9612 under salt stress, of which 10 were upregulated and 2 were downregulated. In the matrix-assisted laser desorption-ionization/time of flight-time of flight/MS analysis, 14 differentially expressed proteins were successfully identified, including the ribulose-1, 5-bisphosphate carboxylase/oxygenase (RuBisco) large subunit-binding protein subunit alpha (RuBisco α), luminal binding protein (LBP), heat shock protein 70 (Hsp1, 2, 3), pathogenesis-related protein class 10 (PR-10), quinoneoxidoreductase-like protein (QOR), S-adenosylmethioninesyn-thetase (SAMS), enolase (EN), and RuBisco large subunit-binding protein subunit beta (RuBisco β). Cellular function is ultimately executed by proteins, and cotton varieties with different salt tolerance can be influenced by salt stress to various degrees, which can provide certain theoretical foundation for the identification of salt tolerance of cotton varieties. The findings also provide some proteins, such as the RuBisco large subunit binding proteins α and β subunits, OEE2 protein, HSP70, and S-adenosylmethionine synthetase, which can be used as protein markers of salt-to-lerance before- and post-treatment, making a big difference in salt-tolerance identification in cotton.

Intron-Targeted Intron-Exon Splice Conjunction (IT-ISJ) Marker and Its Application in Construction of Upland Cotton Linkage Map

To develop a new DNA maker, which could be used in genetic diversity analysis and genetic map construction in plants, IT-ISJ （intron targeted intron-exon splice junction） primer combinations, which were designed according to the intronexon splice junction conserved sequences, were used to construct cotton genetic linkage map in the present study. 49 out of 704 IT-ISJ primer combinations showed polymorphism between upland cotton high quality cultivar Yumian 1 and multiple dominant gene line T586, and the polymorphic primer combinations accounted for 7.0% of total primer combinations. 49 IT-ISJ primer combinations were used to genotype 270 F2：7 recombinant inbred lines developed from （Yumian 1 × T586） F2, and 58 IT-ISJ loci were obtained. 58 IT-ISJ, together with 150 SSR and 8 morphological loci, were used to conduct linkage analysis, and a linkage map including 22 linkage groups and 113 loci （49 IT-ISJ, 62 SSR, and 2 morphological loci） was constructed. The linkage map covered 714.5 cM with an average interval of 6.3 cM between two markers, accounting for 16.1% of cotton genome. The present study demonstrated that the polymorphism of IT-ISJ marker is high, and it could be effectively applied in plant genetic map construction.

Cultivar Selection and Test Site Evaluation of Cotton Regional Trials in Jiangsu Province Based on GGE Biplot

This study was to evaluate the high yielding and stability of candidate cultivars, depict the adaptive planting region, analyze trial location discrim-ination ability and representativeness, as wel as identify the ideal cultivar and trial location, with the aim to provide theory background for cultivar selection and rea-sonable scheme of test location in Jiangsu Province. [Method] The GGE biplot method was used to analyze the lint cotton yield of 12 experimental genotypes in the 6 test locations （three replicates in each） of the cotton regional trial in Jiangsu Province in 2013. [Result] The effects of genotype （G）, environment （E）, and geno-type by environment interaction （G＆#215;E） on lint cotton yield were al highly significant （P〈0.01）, which made it necessary to further explore the specific pattern of geno-type by environment interaction. Jinmian118 （G4） and SF3303 （G5） were the best ideal genotypes screened by the ＂ideal cultivar＂ and ＂ideal location＂ view of GGE biplot, and the ordination of test sites based on the ideal index were in the order of Dafeng （DF）, Yanliang （YL）, Liuhe （LH）, Dongtai （DT）, Yancheng （YC）, and Nantong （NT）, among which NT was relatively weak in representing of the whole target cot-ton planting region in Jiangsu Province. The ＂similarity among locations＂ view of GGE biplot clustered al trial locations into one group, showing that the test sites in the cotton planting region in Jiangsu Province were in the same mega-environment. The ＂which-won-where＂ view of GGE biplot indicated that cotton cultivar Jinmian118 （G4） was the most appropriate cultivar in the homogeneous cotton planting region in Jiangsu Province. [Conclusion] Among the candidate cultivars, Jinmian118 and SF3303 were identified as the most ideal cultivars in this set of conventional cotton regional trial in Jiangsu Province; the test site of Dafeng ranked the first out of al locations in terms of discrimination and representativeness, and al test locations were clustered into the same mega-environmet, which indicated the high efficiency of cultivar selection in the cotton regional trial in Jiangsu Province.

Selection and Characterization of a Novel Glyphosate Tolerant Upland Cotton(Gossypium hirsutum L.) Mutant(R1098)

Stepwise selection approach was adopted to obtain glyphosate-tolerant upland cotton mutant(R1098) from the embryogenic calli of Coker 312(Gossypium hirsutum L.).The calli were transferred to selection medium and multi-step selection pressure process was carried out until the

Cotton Physiological Parameters Affected by Episodic Irrigation Interruption

Improving cotton irrigation management practices in West Texas is important for increasing farmers＇ profits and for sustainability of the Ogallala aquifer. The objective of this work was to evaluate the effects in field controlled episodic drought conditions on cotton gas exchange. Irrigated cotton was subjected to water stress at different timings. Irrigation was interrupted at the squaring stage, early flowering stage, from three weeks at peak bloom, and from peak bloom to the crop termination. These episodic drought treatments were compared with cotton fully irrigated throughout the whole season. From 2010 to 2012, cotton cultivar FM9180 gas exchange was measured throughout the season using a LiCor-6400 portable photosynthesis system. In 2011 and 2012, measurements were also made on DP0935 cultivar. The cotton physiological parameters evaluated included photosynthesis, transpiration and temperature. From the several parameters evaluated, some relationships were presented. Episodic drought periods can affect leaf-level gas exchange and impact yield. Photosynthesis and yield were particularly sensitive to water deficit at early flowering. Despite an increase in leaf water use efficiency under water deficit, overall growth and yield were inhibited in all treatments with a stress component. Understanding the relative sensitivity at different growth stages can help with irrigation decisions when water resources are limited.