多环境下陆地棉(Gossypium hirsutum L.)重组自交系铃重与衣分性状的QTL分析

本研究利用以SGK9708为母本,0-153为父本构建的196个陆地棉重组自交系(F6:8)构建了包含186个标记,总长827.84cM,标记间平均距离4.45cM,覆盖棉花基因组18.6%的遗传连锁图谱,并对7个环境下的铃重和衣分性状进行QTL定位和上位性互作分析。利用两种分析软件(WinQTLcart2.5和QTLNetwork2.0)共同定位了多个环境下稳定表达的5个主效QTLs(qBW-1-1,qBW-1-2,qLP-2-1,qLP-2-2和qLP-4-2)。利用QTLNetwork2.0分别检测到4对铃重上位性互作QTLs和7对衣分上位性互作QTLs,以背景位点间的互作和加性效应位点与背景位点间的互作为主。除主效QTL外,上位性效应也是陆地棉铃重和衣分性状的重要遗传基础。本研究定位的5个主效QTLs为选择高铃重、高衣分品种的棉花分子标记辅助育种提供了重要依据。

棉花(Gossypium hirsutum L.)原生质体培养的体细胞胚胎发生及植株再生

以陆地棉(G.hirsutum L.)3118、晋棉4号和柯字棉312等3个品种为材料,取种子无菌苗的下胚轴诱导愈伤组织,建立胚性细胞悬浮培养系。以2％纤维素酶Ono-zuka RS和0.1％离析软化酶Y-23组成的混合酶液,从细胞悬浮培养物游离出原生质体。用含低融点琼脂糖的K_3培养基包埋原生质体,采用园柱及薄层漂浮平板培养方式。3个品种的原生质体培养都得到了愈伤组织,其中晋棉4号和柯字棉312品种的愈伤组织转到低激素水平或无激素的MS-2培养基上诱导产生胚状体,胚状体在无激素的MS-1培养基上形成了植株。

施氮量对不同开花期棉(Gossypium hirsutum L．)铃纤维细度和成熟度形成的影响

为兼顾试验的重复性和生态区域性,选用高品质棉(科棉1号)和常规棉(美棉33B)品种为材料,于2005年分别在江苏南京(118°50'E,32°02'N,长江流域下游棉区)和江苏徐州(117°11'E,34°15'N,黄河流域黄淮棉区)设置施氮量(低氮N 0 kg/hm2;适氮N 240 kg/hm2;高氮N 480 kg/hm2)试验,研究施氮量对不同开花期棉铃纤维细度、成熟度和马克隆值形成的影响。结果表明,(1)施氮量显著影响棉纤维细度、成熟度和马克隆值的形成过程,但三者在不同开花期对氮素水平的响应不同,施氮量与开花期对棉纤维细度、成熟度和马克隆值的形成存在互作效应。8月10日前开花的棉铃,铃期[花后0～50 d(DPA)]日均温在23.3℃以上,纤维细度、马克隆值以N 0 kg/hm2施氮量下最大,棉纤维马克隆值与纤维细度的相关性较大;8月25日开花的棉铃(铃期日均温在20.8～23.3℃之间),纤维成熟度、马克隆值以N 240 kg/hm2施氮量下最大;9月10日开花棉铃(铃期日均温低于20.8℃),纤维细度、成熟度和马克隆值均以N 480 kg/hm2最大,棉纤维马克隆值与纤维成熟度的相关性增强。(2)影响不同开花期间纤维细度、成熟度和马克隆值的主要因素是铃期日均温;最终纤维细度、成熟度和马克隆值在不同施氮量之间的变异与不同开花期(铃期日均温不同)间的变异比较,前者显著小于后者。综上,因开花期不同而形成的铃期日均温是决定纤维细度、成熟度和马克隆值的最重要因素,施氮量可通过对位叶叶氮浓度NA影响棉纤维细度、成熟度和马克隆值的形成过程,增加施氮量可减小上述指标在不同开花期间的差异。

棉花(Gossypium hirsutum L.)花粉壁的发育

用光镜和透射电镜观察研究了棉花花粉壁的发育过程.棉花花粉壁的发生始于四分孢子时期,四分体形成后,在小孢子的质膜与胼胝质壁之间逐渐形成多糖性质的原外壁.游离小孢子时期,在一定间隔的原外壁中小孢子质膜表面积累外壁物质并形成基粒棒,之后在基粒棒的下部和上部分别横向延展并接合形成基足层和覆盖层.花粉内壁发生时期较晚,大约在大液泡形成之前.但内层和外层花粉壁均在小孢子有丝分裂之前同时建成.构建花粉壁的物质主要来自绒毡层的周原质团和小孢子原生质体的代谢分泌.小孢子胞质中在四分体时期形成的巨型内质网复合体是较为特殊的细胞结构,在游离小孢子时期,巨型内质网不断产生大量的内含微粒物的运输小泡,这种小囊泡表现出向质膜趋向运动并进一步与质膜融合.推测由内质网复合体产生的这些小囊泡是小孢子原生质体向质膜外运输花粉壁构建物质的主要形式.

陆地棉(Gossypium hirsutum L.)单体的诱发和鉴定

以隐性亲本(芽黄 v_1,v_6,v_8,v_(10),v_(11),T582,TM-1)作母本,授以辐射处理的显性亲本(TM-1,2256-61,陕1155,泗棉2号,Rd,T586)的花粉,进行单体的诱发研究。通过对 F_1表型为隐性或畸形的植株,在现蕾时观察其减数分裂时的染色体构型,发现有单倍体的存在。并将单体作母本,用相应的易位系测验,鉴定了诱发得到的单体株分别为单体1、6、7。辐射剂量为800伦琴和500伦琴,其诱致单体的频率分列为20.5%和9.8%。发现高剂量比低剂量更能诱致染色体的丢失,特别是小染色体的丢失,并且高剂量诱致的染色体结构变异也增加。

Bioinformatics Analysis of PHYB Gene in Upland Cotton(Gossypium hirsutum)

[Objective] This study was conducted to clarify the biological information of PHYB genes in upland cotton （Gossypium hirsutum）. [Method] Two PHYB genes were identified from the genome database of allotetraploid cotton （G. hirsutum L. acc. TM-1）, and were found to be distributed on subgenomes A10 and D10. And then bioinformatic analysis on these two genes were performed. [Result] The PHYB genes of upland cotton had the same motifs and domains with the PHYB genes in other plant species, and even the number and location of the motifs and domains of these PHYB genes were consistent. The PHYB amino acid sequence alignment and the phylogenetic tree constructed based on PHYB amino acid sequence of these plant species indicated that the two PHYB genes in upland cotton had higher homology and closer evolutionary relationships with cocoa （Theobroma cacao）, but lower similarity to PHYB genes in monocotyledonous plants, such as rice （Oryza saitva） and corn （Zea mays）. The comparison of PHYB gene structure also revealed that plant PHYB gene was more conserved during evolution. The autophosphorylation of dozens of phosphorylation sites in upland cotton PHYB gene may be essential for the functions of phytochromes and plays a significant role in regulating phytochrome-mediated signal transduction pathways. [Conclusion] The results of this paper will provide a theoretical basis for the cloning and functional research of PHYB genes.

利用重组自交系进行陆地棉(GossypiumhirsutumL.)棉籽油分含量和蛋白质含量的QTL定位

本研究利用以0—153为父本和SGK9708为母本构建的196个陆地棉重组自交系（F6：8）为材料对棉籽油分含量和蛋白质含量进行了遗传分析和QTL定位。通过四个环境下的群体材料的棉籽油分含量和蛋白质含量分析表明棉籽油分含量和蛋白质含量均为典型数量性状，其中棉籽油分含量存在超低亲本的超亲分离，而其蛋白质含量呈现超高亲本的超亲分离。相关性分析显示棉籽油分含量和蛋白质含量呈极显著负相关，同步提高两者在棉籽的的含量较为困难。基于包含186个标记，总长827．84cM，标记间平均距离4．45cM，覆盖棉花基因组18．6％的遗传连锁图谱，应用WinQTLcart2．5软件对四个环境下的棉籽油分含量和蛋白质含量进行了QTL定位，共检测到8个油分含量QTLs，解释表型变异5．42％～13．15％，其中稳定的QTL1个。4个蛋白质含量QTLs，解释表型变异4．35％～14．93％。本研究结果可为进行陆地棉种子营养品质性状的分子遗传改良奠定基础。

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.

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.

Somatic Embryogenesis and Plant Regeneration from Two Recalcitrant Genotypes of Gossypium hirsutum L.

An improved protocol has been developed for somatic embryogenesis and plant regeneration of recalcitrant cotton cultivars. High callus frequencies and embryogenic tissue were developed in MSB medium supplemented with gradient concentrations of KT and 2,4-D, their concentration decreasing from 0.1 to 0.01 mg·L^-1. Somatic embryos were successfully incubated in 1/2 macronutrient MSB suspension supplemented with 0.5 g· L^-1 glutamine and 0.5 g·L^-1 asparagine. Decrease in macronutrient concentration of MSB significantly alleviated browning and was beneficial to suspension cells. Transformation of somatic embryos into plants was induced in MSB medium supplemented with 3% sucrose, 0.5 g·L^-1 glutamine, 0.5 g·L^-1 asparagine, and 6.0 g·L^-1 agar. The effect of sucrose as carbohydrate was better than that of glucose for plant germination. Using this protocol, regenerated plantlets from the CCRI521 and Zhongzhi86-6 reached to as much as 19.6 and 18.5% somatic embryos, respectively.

Ameliorative effects of potassium on drought-induced decreases in fiber length of cotton(Gossypium hirsutum L.) are associated with osmolyte dynamics during fiber development

Fiber length of cotton(Gossypium hirsutum L.)decreases under drought stress,potassium(K)could diminish the decreased caused by drought,but the mechanism associated with this alleviation effect is not clear.We evaluated the effect of K on fiber elongation using two cotton cultivars,Simian 3 and Siza 3,grown in well-watered and drought-stressed conditions.Potassium fertilizer(K2O)was applied 0,150,or 300 kg ha?1 in each growing condition.Drought stress reduced the final fiber length due to a decline in the maximum rate of rapid elongation(Vmax,mmday?1).The application of K alleviated the droughtinduced fiber length reduction by increasing Vmax.At 10 and 15 days post-anthesis(DPA),drought significantly reduced osmotic potential(OP)and increased K+and malate contents at all K rates,relative to well-watered conditions,which was associated with increased activities of phosphoenolpyruvate carboxylase(PEPC),V-ATPase,PPase,and PM H+-ATPase in cotton fiber.However,the relative contribution of K+and malate to OP declined under drought in comparison with well-watered condition.Compared with control without K,K application decreased OP and increased the accumulation of osmolytes(K+,malate and soluble sugar)as well as the activities of related enzymes in fiber irrespective of water treatments.Moreover,K application increased osmotic adjustment during drought,and improved the contribution of K+and malate to OP,especially under drought stress.This study showed that drought decreased fiber length by reducing Vmax,and K application ameliorates the decline in fiber elongation due to drought by enhancing osmolytes accumulation and their contribution to OP in fiber cells.

Isolation and Expression Analysis of Two Genes Encoding Cinnamate 4-Hydroxylase from Cotton(Gossypium hirsutum)

Two genes （GhC4H1 and GhC4H2） that encode putative cotton cinnamate 4-hydroxylases that catalyze the second step in the phenylpropanoid pathway were isolated from developing cotton fibers. GhC4H1 and GhC4H2 each contain open reading frames of 1 518 base pairs （bp） in length and both encode proteins consisting of 505 amino acid residues. They are 90.89% identical to each other at the amino acid sequence level and belong to class I of plant C4Hs. GhC4H1 and GhC4H2 genomic DNA are 2 247 and 2 161 bp long, respectively, and contain two introns located at conserved positions relative to the coding sequence. GhC4HI and GhC4H2 promoters were isolated and found to contain many cis-elements （boxes P, L and AC-1 element） previously identified in the promoters of other phenylpropanoid pathway genes. Histochemical staining showed GUS expression driven by the GhC4H1 and GhC4H2 promoters in ovules and fibers tissues. GhC4H1 and GhC4H2 were also widely expressed in other cotton tissues. GhC4H2 expression reached its highest level during the elongation stage of fiber development, whereas GhC4H1 expression increased during the secondary wall development period in cotton fibers. Our results contribute to a better understanding of the biochemical role of GhC4H1 and GhC4H2 in cotton fiber development.

Genetic variation in LBL1 contributes to depth of leaf blades lobes between cotton subspecies, Gossypium barbadense and Gossypium hirsutum

Leaf is a essential part of the plants for photosynthetic activities which mainly economize the resources for boll heath. Significant variations of leaf shapes across the Gossypium sp. considerably influence the infiltration of sunlight for photosynthesis. To understand the genetic variants and molecular processes underlying for cotton leaf shape, we used F2 population derived from upland cotton genotype P30A （shallow-lobed leaf） and sea-island cotton genotype ISR （deep-lobed leaf） to map leaf deep lobed phenotype controlling genes LBL1 and LBL2. Genetic analysis and localization results have unmasked the position and interaction between both loci of LBL1 and LBL2, and revealed the co-dominance impact of the genes in regulating depth of leaf blades lobes in cotton. LBL1 had been described as a main gene and member of transcription factor family leucine zipper （HD-ZIPI） from a class I homologous domain factor Gorai.OO2G244000. The qRT-PCR results elaborated the continuous change in expression level of LBL1 at different growth stages and leaf parts of cotton. Higher expression level was observed in mature large leaves followed by medium and young leaves respectively. For further confirmation, plants were tested from hormonal induction treatments, which explained that LBL 1 expression was influenced by hormonal signaling. Moreover, the highest expression level was detected in brassinolides （BR） treatment as compared to other hormones, and this hormone plays an important role in the process of leaf blade lobed formation.

The G-protein α subunit GhGPA positively regulates Gossypium hirsutum resistance to Verticillium dahliae via induction of SA and JA signaling pathways and ROS accumulation

Verticillium wilt, a devastating disease in cotton caused by Verticillium dahliae, reduces cotton quality and yield. Heterotrimeric GTP-binding proteins, consisting of Ga, Gb, and Gc subunits, transducers of receptor signaling, function in a wide range of biological events. However, the function of Ga proteins in the regulation of defense responses in plants is largely unexplored, except for a few reports on model species. In the present study, a cotton G-protein a-subunit-encoding gene(GhGPA) was isolated from Verticillium wilt-resistant Gossypium hirsutum(upland cotton) cv. ND601. GhGPA transcription was up-regulated under V. dahliae stress, with higher expression in tolerant than in susceptible cotton cultivars.Subcellular localization revealed GhGPA to be located in the plasma membrane. GhGPA shows high(85.0%) identity with Arabidopsis AT2 G26300(AtGPA1), and AtGPA1 gpa1-4 mutants displayed susceptibility to V. dahliae. Ectopic expression of GhGPA successfully restored the resistance of Arabidopsis gpa1-4 mutants to Verticillium wilt and made them more resistant than the wild type. Overexpression of GhGPA in Arabidopsis markedly increased the resistance and resulted in dramatic up-regulation of pathogenesis-related(PR) genes and increased in H2 O2 accumulation and salicylic acid(SA) and jasmonic acid(JA) contents. However, suppressing GhGPA expression via virus-induced gene silencing(VIGS)increased susceptibility to Verticillium wilt, down-regulated the expression of PR and marker genes in SA and JA signaling pathways, and reduced H2 O2 content. The contents of SA and JA in Arabidopsis gpa1-4 and VIGS cotton were lower than those in the wild type and empty-vector control. However,GhGPA-overexpressing Arabidopsis contained more SA and JA than the wild type when inoculated with V. dahliae. Thus, GhGPA plays a vital role in Verticillium wilt resistance by inducing SA and JA signaling pathways and regulating the production of reactive oxygen species. These findings not only broaden our knowledge about the biological role of GhGPA, but also shed light on the defense mechanisms involving GhGPA against V. dahliae in cotton.

Molecular Cloning and Characterization of Three Novel Genes Related to Fatty Acid Degradation and Their Responses to Abiotic Stresses in Gossypium hirsutum L.

Fatty acid metabolism is responsible not only for oilseed metabolism but also for plant responses to abiotic stresses. In this study, three novel genes related to fatty acid degradation designated GhACX, Gh4CL, and GhMFP, respectively, were isolated from Gossypium hirsutum acc. TM-1. The phylogenetic analysis revealed that amino acid sequences of GhACXand GhMFP have the highest homology with those from Vitis vinifera, and Gh4CL has a closer genetic relationship with that from Camellia sinensis. Tissue- and organ-specific analysis showed that the three genes expressed widely in all the tested tissues, including ovules and fiber at different developing stages, with expressed preferentially in some organs. Among them, GhACX showed the most abundant transcripts in seeds at 25 d post anthesis （DPA）, however, GhMFP and Gh4CL have the strongest expression level in ovules on the day of anthesis. Based on real-time quantitative RT-PCR, the three genes were differentially regulated when induced under wounding, methyl jasmonate （MeJA）, cold, and abscisic acid （ABA） treatments. The characterization and expression pattern of three novel fatty acid degradation related genes will aid both to understand the roles of fatty acid degradation related genes as precursor in stress stimuli and to elucidate the physiological function in cotton oilseed metabolism.

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.

Cloning and Characterization of a Somatic Embryogenesis Receptor-Like Kinase Gene in Cotton (Gossypium hirsutum)

A novel gene, GhSERK1, was identified in cotton. It encoded a protein belonging to the somatic embryogenesis receptor- like kinase （SERK） family. The genomic sequence of GhSERK1 was 6 920 bp in length, containing a predicted transcriptional start site （TSS）. Its full-length cDNA was 2 502 bp, encoding a protein of 627 amino acids. Sequence analysis of GhSERK1 revealed high levels of similarity to other reported SERKs, as well as a conserved intron/exon structure that was unique to members of the SERK family. Expression analysis showed that GhSERK1 mRNA was present in all organs of cotton plants and at different developmental stages, but its transcripts were most abundant in reproductive organs. Compared with that of the male-fertile line, the level of GhSERK1 mRNA was lower in the anther of the male-sterile cotton line, in which the pollen development was defected. Taken together, these findings illustrated that the GhSERK1 play a critical role during the anther formation, and may also have a broad role in other aspects of plant development.

过表达番茄LeDnaJ基因提高陆地棉(Gossypium hirsutum Linn.)R15的耐盐性

DnaJ蛋白不仅在生物体应对热激胁迫方面起作用,而且能响应盐、重金属和氧化等多种胁迫,因此,DnaJ蛋白的相关研究对植物抗逆研究具有重要意义。在前期的研究中,笔者所在课题组已经利用电子克隆及逆转录-聚合酶链式反应(RT-PCR)的方法从番茄中克隆了全长为465 bp的热激蛋白基因LeDnaJ。为了进一步验证其功能,针对LeDnaJ基因构建了含有35S启动子及NOS终止子的植物表达载体,通过农杆菌介导法转化到陆地棉(Gossypium hirsutum Linn.)品系R15中。目的基因的PCR检测结果表明,LeDnaJ基因已经整合到陆地棉R15基因组中;耐盐性鉴定结果表明,LeDnaJ基因的表达,提高了陆地棉R15萌发期、苗期的耐盐性。该研究结果为棉花耐盐性的改良提供了新的基因资源。

Genome-wide assessment of genetic diversity and fiber quality traits characterization in Gossypium hirsutum races

Gossypium hirsutum races are believed to be potential reservoirs of desirable traits, which can play crucial roles to overcome the existing narrow genetic base of modern Upland cotton cultivars. However, prior to utilizing the races in cotton improve- ment programs, understanding their genetic constitutions is needed. Thus, this study used molecular and morphological techniques to characterize 110 G. hirsutum germplasm including 109 semi-wild accessions and one Upland cotton cultivar, CRI12. In the study, 104 SSR markers detected 795 alleles, with an average of 7.64 alleles per marker, ranging from 3 to 14, and average polymorphism information content （PIC） value of 0.71. And 96 of the markers were found to be highly informative, with PIC value〉0.50. Pairwise genetic similarity coefficient across the accessions ranged from 0.19 to 1.00, with an average value of 0.46. Morphological characterization was done using fiber length, fiber strength, micronaire, fiber uniformity index, and fiber elongation. Pairwise taxonomic distance within the accessions ranged from 0.17 to 3.41, with a mean of 1.33. The SSR and fiber quality traits data set based unweighted pair group method of arithmetic mean （UPGMA） analysis grouped the accessions into 7 and 12 distinct clusters, respectively, that corresponds well with the results of prin- cipal component analysis （PCA）. Our study revealed the existence of vast molecular and morphological diversities within the accessions and provided valuable information on each semi-wild accession for quick and better informed germplasm utilization in cotton breeding programs.

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.