Interspecific Chromosome Substitution Lines as Genetic Resources for Improvement,Trait Analysis and Genomic Inference

The genetic base that cotton breeders commonly use to improve Upland cultivars is very narrow.The AD-genome species Gossypium barbadense,G.tomentosum,and G.mustelinum are part of the primary germplasm pool,too,and constitute genetic reservoirs of genes for resistance to abiotic stress,pests,and pathogens,as well as agronomic and fiber traits.     

棉属种间杂交基因渐渗系SSR标记及其表型性状的聚类分析

利用37对多态性SSR引物和15个表型性状对155份棉属种间杂交基因渐渗系及其10份陆地棉亲本进行了聚类分析。用37对SSR引物共扩增出108条带,多态性条带占85.2％。种质间成对相似系数平均值为0.6791,范围为0.4762~1.000。建立了165个陆地棉材料的SSR聚类图,共聚为4个类群,分别为法国种质群、美国AcalaSJ系列种质群、美国PD种     

Genotypic comparisons of chromosomes 01, 04, and 18 from three tetraploid species of <Emphasis Type="Italic">Gossypium</Emphasis> in topcrosses with five elite cultivars of <Emphasis Type="Italic">G. hirsutum</Emphasis> L.

Upland cotton, Gossypium hirsutum L. is the most widely planted cultivated cotton in the United States and the world. The other cultivated tetraploid species G. barbadense L. is planted on considerable less area; however, it produces extra long, strong, and fine fibers which spins into superior yarn. The wild cotton tetraploid species G. tomentosum Nuttall ex Seemann, native to the Hawaiian Archipelago also exhibits traits, such as drought tolerance, that would also be desirable to transfer to Upland cotton. Long-term breeding efforts using whole genome crosses between Upland and these species have not been successful in transferring very many desirable alleles into Upland cotton. Our chromosome substitution lines (CSL) have one chromosome or chromosome arm from an alien species backcrossed into the Upland cotton line,TM-1, via aneuploid technology. Five Upland cultivars were crossed with CS-B01, CS-T01, CS-B04, CS-T04, CS-B18 and CS-T18 and TM-1 the recurrent parent of the CSLs. This provided an opportunity to determine the effects of chromosomes 01, 04, and 18 from the three species in crosses with the five cultivars. Predicted genotypic mean effects of the parents, F₂, and F₃ generations for eight agronomic and fiber traits of importance were compared. The predicted hybrid mean effects for the three chromosomes from each species were different for several of the traits across cultivars. There was no single chromosome or species that was superior for all traits in crosses. Parental and hybrid lines often differed in the effect of a particular chromosome among the three species. The predicted genotypic mean effects for F₂ and F₃, with a few exceptions, generally agree with our previous results for additive and dominance genetic effects of these CSL.     

Introgression genetics and breeding between Upland and Pima cotton: a review

The narrow genetic base of elite Upland cotton (Gossypium hirsutum L.) germplasm has been a significant impediment to sustained progress in the development of cotton cultivars to meet the needs of growers and industry in recent years. The prospect of widening the genetic base of Upland cotton by accessing the genetic diversity and fiber quality of Pima cotton (Gossypium barbadense L.) has encouraged interspecific hybridization and introgression efforts for the past century. However, success is limited due mainly to genetic barriers between the two species in the forms of divergent gene regulatory systems, accumulated gene mutations, gene order rearrangements and cryptic chromosomal structure differences that have resulted in hybrid breakdown, hybrid sterility and selective elimination of genes. The objective of this paper is to provide a mini-review in interspecific hybridization between Upland and Pima cotton relevant to breeding under the following sections: (1) qualitative genetics; (2) cytogenetic stocks; (3) quantitative genetics; (4) heterosis, and (5) introgression breeding. Case studies of successful examples are provided.     

Germplasm evaluation and transfer of Verticillium wilt resistance from Pima (<Emphasis Type="Italic">Gossypium barbadense</Emphasis>) to Upland cotton (<Emphasis Type="Italic">G. hirsutum</Emphasis>)

Verticillium wilt (VW, Verticillium dahliae) is a worldwide destructive soil-borne fungal disease and employment of VW resistant cultivars is the most economic and efficient method in sustainable cotton production. However, information concerning VW resistance in current commercial cotton cultivars and transfer of VW resistance from Pima (Gossypium barbadense) to Upland (Gossypium hirsutum) cotton is lacking. The objective of the current study was to report findings in evaluating commercial cotton cultivars and germplasm lines for VW resistance in field and greenhouse (GH) experiments conducted in 2003, 2006, and 2007. In the study, 267 cultivars and germplasm lines were screened in the GH, while 357 genotypes were screened in the field. The results indicated that (1) VW significantly reduced cotton yield, lint percentage, 50% span length and micronaire, but not 2.5% span length and fiber strength, when healthy and diseased plants in 23 cultivars were compared; (2) some commercial cotton cultivars developed by major cotton seed companies in the US displayed good VW resistance; (3) many Acala cotton cultivars released in the past also had good VW resistance, but not all Acala cotton germplasm are resistant; (4) Pima cotton possessed higher levels of VW resistance than Upland cotton, but the performance was reversed when the root system was wounded after inoculation; (5) VW resistance in some conventional cultivars was transferred into their transgenic version through backcrossing; and (6) some advanced backcross inbred lines developed from a cross between Upland and Pima cotton showed good VW resistance. The successful development of VW resistant transgenic cultivars and transfer of VW resistance from Pima to Upland cotton implies that VW resistance is associated with a few genes if not a major one.     

Genetic diversity for agronomic and fiber traits in day-neutral accessions derived from primitive cotton germplasm

Upland cotton (Gossypium hirsutumL) is an important crop that is cultivated in warm climates through-out the world. Agronomic performance and fiber quality must continually be improved if cotton is to maintain economic viability. Primitive ancestors of cotton contain diversity for trait improvement; however, many of these accessions have a short-day flowering response (photoperiodic) and are not readily useable in breeding programs. In this study, 114 day-neutral derived primitive germplasm lines were evaluated in field trials for two years. Agronomic and fiber trait data were collected and analyzed. Variance components, genotypic values, and genotypic correlations were calculated. Genotypic effects for all traits studied made significant contributions to the phenotypic variation indicating genetic diversity among these lines. The predicted genotypic values showed a wide range of variation for agronomic and fiber traits. Weak genotypic correlations were found between yield and 2.5% span length and fiber strength, two important fiber traits. Although these day-neutral derived accessions had lower lint percentage, they had improved fiber length, strength, micronaire, and comparable yields with two commercial cultivars. Thus, these day-neutral derived accessions are sources of genetic variation that when used in breeding programs offer the potential to improve important traits and expand genetic diversity.Contribution of the USDA-ARS in cooperation with the Mississippi Agric. and Forestry Exp. Stn. Mention of trademark, proprietary product, or vendor does not constitute a guarantee or warranty of the product by USDA, ARS and does not imply its approval to the exclusion of other products or vendors that may also be suitable.     

棉属野生种克劳茨基棉(Gossypium klotzschianum)基因组向陆地棉的渐渗

 棉花远缘种质是改良栽培种的丰富资源,野生种遗传变异的有效利用依赖于鉴定并渐渗理想的野生种DNA进入栽培种的能力。为了检测二倍体野生种克劳茨基棉染色质在陆地棉中的渐渗情况,构建了一个来自于（陆地棉×克劳茨基棉）×陆地棉的BC₁ F₂群体,并用320个覆盖棉花基因组的SSR标记来监测外源种质的转入;只有38个标记在BC₁F₂群体中显示了分离,这些标记分布于14条染色体,组成了18个渐渗片段;通过比较发表的棉花遗传图谱,这18条渐渗片段的总长为595 cM;同时两个形态性状（黄色花瓣和开放花蕾）被定位于13号染色体。通过分子和形态鉴定,结果证实克劳茨基棉染色质已被渐渗进陆地棉遗传背景中。利用这种特异的标记将会促进理想的外源基因转入栽培棉。     

Genetic variation and selection within glandless cotton germplasm

There is a renewed interest in research and use of glandless (free of gossypol) Upland cotton (Gossypium hirsutum L.) that can produce edible seeds for human food and animal feed. However, there was a lack of information on yield potential of existing glandless germplasm since intermittent breeding activities for glandless cotton were stopped in the U.S. before 2000. The objectives of the present study were to test obsolete and exotic glandless germplasm for possible production and evaluate progress in direct pedigree selection within the existing glandless germplasm in eight field tests. In multiple tests, the glandless cotton Acala GLS yielded only 65–80 % lint of the glanded control Acala 1517-08 and 46–75 % lint of commercial transgenic cultivars. Most of obsolete glandless germplasm and their selections yielded <70 % of Acala 1517-08 and only three selections yielded 82–89 % of the control. Genetic variation in yield and fiber quality traits was seen from significant differences between selections within the same glandless germplasm, indicating the existence of residual genetic variation. Most importantly, three selections from exotic glandless germplasm out-yielded Acala 1517-08 by 4–9 %, one of which had desirable fiber quality traits. These promising glandless lines with comparable yields to commercial cotton make it possible to revitalize the glandless cotton industry. More field tests will be needed to evaluate their yield potential and adaptability in the U.S. Cotton Belt.     

Quantitative trait locus mapping of drought and salt tolerance in an introgressed recombinant inbred line population of Upland cotton under the greenhouse and field conditions

Drought and salt tolerances are complex traits and controlled by multiple genes, environmental factors and their interactions. Drought and salt stresses can result in more than 50% yield loss in Upland cotton (Gossypium hirsutum L.). G. barbadense L. (the source of Pima cotton) carries desirable traits such as tolerance to abiotic and biotic stress along with high fiber quality. However, few studies have been reported on mapping quantitative trait loci (QTL) for abiotic stress tolerance using a permanent bi-parental population in multiple tests. The transfer of drought and salt tolerance from Pima to Upland cotton has been a challenge due to interspecific hybrid breakdown. This issue may be overcome by using introgression lines with genes transferred from Pima to Upland cotton. In this study, four replicated tests were conducted in the greenhouse each for drought and salt tolerance along with another test conducted in a field for drought tolerance using an Upland recombinant inbred line population of TM-1/NM24016 that has a stable introgression from Pima cotton. The objectives of the study were to investigate the genetic basis of drought and salt tolerance and to identify genetic markers associated with the abiotic stress tolerance. A total of 1004 polymorphic DNA marker loci including RGA-AFLP, SSR and GBS-SNP markers were used to construct a genetic map spanning 2221.28 cM. This population together with its two parents was evaluated for morphological, physiological, yield and fiber quality traits. The results showed that drought under greenhouse and field conditions and salt stress in the greenhouse reduced cotton plant growth at the seedling stage, and decreased lint yield and fiber quality traits in the field. A total of 165 QTL for salt and drought tolerance were detected on most of the cotton chromosomes, each explaining 5.98–21.43% of the phenotypic variation. Among these, common QTL for salt and drought tolerance were detected under both the greenhouse and field conditions. This study represents the first study to report consistent abiotic stress tolerance QTL from multiple tests in the greenhouse and the field that will be useful to understand the genetic basis of drought and salt tolerance and to breeding for abiotic stress tolerance using molecular marker-assisted selection in cotton.     

Morph-physiological responses of cotton interspecific chromosome substitution lines to low temperature and drought stresses

Limited knowledge about genetic and physiological traits associated with drought and low temperature stresses and narrow genetic diversity in Upland cotton (Gossypium hirsutum L.) are serious impediments in its genetic improvement. The objectives of this research were to determine the genetic and physiological traits associated with drought and low temperature effects and to identify chromosomal effects on these traits using chromosome substitution (CS) lines from three alien species of Gossypium, G. barbadense, G. tomentosum, and G. mustelinum, respectively. Two experiments were conducted to study low temperature and drought stress effects during seedling emergence and early growth stages in 21 cotton CS-lines with parent, Texas Marker (TM)-1. In Experiment I, plants were grown at optimum (30/22 °C) and low (22/14 °C) temperature conditions under optimum water and nutrient conditions. In Experiment II, plants were grown at optimum water (soil moisture content of 0.167 m³ m^?3) and in drought (soil moisture content 0.105 m³ m^?3) conditions under optimum temperature conditions. Above- and below-ground growth traits including several root traits of the CS lines were assessed at 25 days after sowing. The findings suggest which substituted chromosome or chromosome segment from the alien species likely harbors one or more genes for higher and lower tolerance to low temperature, respectively. CS-T04 and CSB08sh showed higher and lower tolerance to low temperature, respectively and CS-T04 and CS-B22sh showed higher and lower tolerance, respectively, to drought. CS lines are valuable analytical tool and useful genetic resources for targeted exploitation of beneficial genes for drought and low temperature stresses in Upland cotton.     

Using molecular markers and field performance data to characterize the Pee Dee cotton germplasm resources

Knowledge of genetic relationships in crop breeding programs provides valuable information that can be used by plant breeders as a parental line selection tool. In Upland cotton (Gossypium hirsutum L.), the Pee Dee germplasm program represents one of the most historically significant Upland cotton breeding programs and is known as a key source of fiber quality genes for commercial cultivars. The foundation of the Pee Dee germplasm is known to represent an array of genetic diversity involving the hybridization of G. hirsutum L., G. barbadense L., and triple hybrid strains (G. arboreum L. × G. thurberi Todaro × G. hirsutum L.). In this study, we characterized genetic relationships within the Pee Dee germplasm collection using molecular marker and field performance data. Molecular marker and field performance data showed the Pee Dee germplasm collection still maintains useful amounts of genetic diversity. The methods described provide plant breeders of cotton and other crops a strategy to develop a parental line selection tool based on genotypic and phenotypic information. Cotton breeders can directly use the information provided to select specific Pee Dee germplasm parental line combinations based on genotypic (molecular marker) and phenotypic (field performance) information rather than relying on pedigree and phenotypic information alone.     

棉花功能基因组研究进展

棉花是重要的经济作物。近年来棉花功能基因组研究发展迅速,高通量测序技术应用于棉花研究,二倍体和四倍体棉花基因组测序陆续完成,棉花全基因组重测序及关联分析相继涌现,大量的棉花功能基因被分离鉴定。本文回顾了棉花功能基因组研究的历程,重点介绍了棉花基因组测序和棉花栽培品种全基因组关联分析相关研究成果,并总结了棉花纤维和腺体发育中的关键功能基因及棉花抗旱、抗盐碱等功能基因研究进展,为全面了解棉花重要农艺性状形成的遗传基础和棉花遗传改良提供理论参考。     

陆地棉产量相关性状的QTL定位

中棉所28和湘杂棉2号分别是以中棉所12×4133和中棉所12×8891配制而成的两个陆地棉强优势杂交种。以其F₂为作图群体,筛选6000多对SSR引物,利用两群体间27个共有多态位点,通过JoinMap 3.0软件整合了一张包含245个多态位点、全长1847.81 cM的遗传图谱。利用Win QTLCart 2.5复合区间作图法分别对两群体8个产量相关性状在F₂和F_2:3中进行QTL定位,在中棉所28群体多环境平均值的联合分析中检测到16个QTL,三环境分离分析中检测到43个QTL;在湘杂棉2号群体分别检测到20个和66个QTL。在A3、D8、D9等染色体上有QTL成簇分布现象,同时在两个群体中发现一些不受环境影响且稳定遗传的QTL。对考察的8个性状在两个群体中发现12对共有QTL,控制果枝数、衣分和籽指的QTL增效基因位点均来源于共同亲本中棉所12。综合分析推测中棉所12的育种价值主要是通过提高后代的结铃性来实现的。研究结果为棉花产量性状的分子设计育种提供了有用的信息。     

墨西哥棉花种质资源及其对世界棉花生产的贡献

根据在墨西哥伊瓜拉格尔热罗自治大学的图斯班联合试验农场国家棉花种质资源保存、种植中心和其它原产地的考察、研究结果,结合查阅和分析有关文献资料和历史证据,对起源于墨西哥的棉花种质资源进行了综合评述。墨西哥是棉属（Ｇｏｓｙｐｉｕｍ）Ｄ基因组（Ｄ１,Ｄ２－１,Ｄ２－２,Ｄ３－ｄ,Ｄ４,Ｄ６,Ｄ７,Ｄ８,Ｄ９,Ｄ１０,Ｄ１１）,陆地棉［Ｇ．ｈｉｒｓｕｔｕｍ（ＡＤ）１］和长矛棉［Ｇ．ｌａｎｃｅｏｌａｔｕｍ（ＡＤ）７］棉种的起源中心。墨西哥的棉花种质资源对现代棉花育种和世界棉花生产作出了巨大的贡献。从起源于墨西哥的陆地棉所培育出的品种,占当前世界棉花生产的９１％以上,亚洲棉（Ｇ．ａｒｂｏｒｅｕｍ）不到４％,海岛棉（Ｇ．ｂａｒｂａｄｅｎｓｅ）约为５％。墨西哥的棉花种质资源,由于没有得到很好地保护和利用,有些野生种或原始陆地棉栽培种已经或正在消失。     

岱字棉来源的陆地棉种质资源的遗传多样性分析

岱字棉曾经作为中国陆地棉种质资源的重要亲本来源之一,促进了中国陆地棉种质资源的创新与发展,为了进一步挖掘具有优良性状的棉花种质资源及为高效利用优异种质提供一定的科学依据。本研究围绕岱字棉来源的147份陆地棉种质资源的纤维品质性状和主要农艺进行各类分析,包括相关性分析、变异分析、主成分分析和聚类分析。结果表明岱字棉来源的147份陆地棉种质资源具有较丰富的遗传多样性,变异分析表明主要农艺性状中变异系数最大的为单株铃数(25.099%)、最小的为株高(5.495%),主要纤维品质性状中变异系数最大的为伸长率(7.904%),最小的为整齐度指数(1.047%),遗传多样性指数以果枝数最高(2.345),第一果枝节位最低(1.940);相关性分析表明在果枝数、单株铃数、株高、第一果枝高度之间,衣分,伸长率,马克隆值之间和断裂比强度、上半部平均长度、整齐度指数之间存在极显著正相关,株高与上半部平均长度呈极显著正相关;伸长率与断裂比强度、上半部平均长度,马克隆值与上半部平均长度均呈极显著负相关;主成分分析表明前5个主成分的累计贡献率达到67.931%,第1主成分主要和棉花纤维品质相关,第2主成分主要与单株铃数、株高、果枝数等农艺性状相关,第3主成分表现出棉花农艺性状与纤维品质性状的相互影响,第4主成分与第5主成分均和棉花产量构成因素相关;聚类分析将147份来源岱字棉的陆地棉种质资源划分为5类,筛选出‘洞庭3号’(岱56-37)、‘安棉3号’、‘中7259’、‘沙帽长桃’(纱帽长桃)、‘赣棉11号’可以作为改良棉花产量构成的材料加以利用,没有马克隆值A级材料。     

Improving Fiber Quality Traits of Xinluzao 45 Using Gossypium barbadense Chromosome Segment Substitution Lines

Gossypium barbadense chromosome segment substitution lines could be used as an important germplasm resource for improving fiber quality traits of upland cotton. In this study, we used TM-1 background substitution lines CSSL-122, the Xinjiang upland cotton Xinluzao 45 and hybrid, backcross progeny BC₂F₁ populations comprising 120 individual plants as test materials. Nineteen SSR markers located in Gossypium barbadense chromosomes land inked with fiber length and strength were used to screen out obvious polymorphic primers between the parents. We then traced and detected chromosome segments of Gossypium barbadense in the BC₂F₁ populations. Simultaneously, we compared fiber quality traits of positive plants that contained Gossypium barbadense chromosome segments with non-positive plants in the BC₂F₁ populations. The results showed that two markers, NAU2987 and BNL3145, which were linked with fiber length, could accurately identify the positive plants. In addition, compared with non-positive plants, the increased fiber length and strength of the positive plants were very significant (P < 0.01). Our research suggested that alien Gossypium barbadense chromosome segments significantly improved the fiber quality traits of Xinluzao 45. Thus, the Gossypium barbadense chromosome segment substitution lines will provide a vital theoretical basis and practical reference for improving Upland Cotton fiber quality traits.     

陆地棉重组自交系群体纤维品质及产量性状遗传变异分析

以陆地棉优质品系0-153和大面积推广的双价转基因抗虫棉品系sGK9708为亲本构建了含有196个F6:8家系的重组自交系群体。在4个环境中,纤维长度、纤维强度、麦克隆值、伸长率、整齐度指数、单株结铃数、铃重、衣分、子指、单株子棉产量及单株皮棉产量等性状均呈正态分布,且存在双向超亲分离。多环境下变异分析表明,各性状家系间及环境间存在极显著差异。除纤维伸长率外,其余各纤维品质及产量性状都具有较高的遗传力,在0.75以上。共有6个家系在纤维长度、细度和强度性状上均超过高亲,可作为优质纤维种质。相关分析显示,有些家系可能打破了纤维品质和产量性状间的负相关。通过聚类分析得出,该群体各系分在了不同的组,表明存在着一定的遗传差异。该群体是进行优异纤维品质相关基础研究的良好材料。     

Genetic effects of nine <Emphasis Type="Italic">Gossypium barbadense</Emphasis> L. chromosome substitution lines in top crosses with five elite Upland cotton <Emphasis Type="Italic">G. hirsutum</Emphasis> L. cultivars

Crosses between Gossypium barbadense L and Gossypium hirsutum L. (Upland cotton) have produced limited success in introgressing fiber quality genes into the latter. Chromosome substitution lines (CSBL) have complete chromosomes or chromosome arms from G. barbadense, line 3-79, substituted for the corresponding chromosome or arms in G. hirsutum in a near isogenic background of TM-1. We top crossed nine CSBL and their parents (TM-1 and 3-79) with five cultivars. Parental lines and their F₂ populations were evaluated in four environments for agronomic and fiber quality traits. The CSBL and their F₂ hybrids showed wide ranges for both agronomic and fiber traits of economic importance. Genetic analysis showed that additive variances were larger than dominance variances for lint percentage, boll weight, lint yield, fiber length, strength, elongation, micronaire, and yellowness; whereas, dominance variances were larger than additive variances only for uniformity of fiber length and equal for fiber reflectance. For all traits, except boll weight and lint yield, significant additive effects of one or more chromosomes from 3-79 in TM-1 background were greater than the corresponding TM-1 chromosome. In addition, we identified specific chromosomes from G. barbadense (3-79) that carry alleles for improvements in specific fiber quality traits in Upland cotton. Favorable additive effects of individual chromosomes or chromosome segments from 3-79 relative to corresponding chromosomes or chromosomes segments from TM-1 were identified in this study as follows: Lint percentage, chromosome/arms 10, 16-15; longer fibers, chromosome/arms 01, 11sh, 26Lo; more uniform fibers, chromosomes/arms 01, 11sh, 10, 17-11; stronger fibers, chromosome/arms 01, 11sh, 12sh, 26Lo, 17-11; fiber elongation, chromosomes/arms 01, 11sh, 26Lo, 10, 17-11; reduced fiber micronaire, chromosome/arms 01, 12sh, 4-15, 16-15, 17-11; fibers with more reflectance, chromosome/arms 10, 4-15, 16-15, 17-11; fiber with less yellowness, chromosome arms 4-15, 17-11. Based on the present study, we concluded that by using CSBL, favorable fiber quality alleles can be introgressed into Upland cotton, thus greatly improving the breeder’s ability for improvement of Upland cotton for a variety of traits. These data should provide useful genetic information to the cotton breeding industry at large.     

Effects of the dominant glandless gene Gl2e on agronomic and fibre characters of Upland cotton

Seven pairs of near‐isogenic lines (glandless vs. glanded) and the recurrent parents were used to determine the effects of the dominant glandless gene from ‘Hai 1’(Gossypium barbadense) on agronomic, fibre, and seed characters in Upland cotton, Gossypium hirsutum, backgrounds. The results showed that there were no apparent linkage associations of the glandless gene on most agronomic, fibre and seed characters of Upland cotton, except for seed quality. The glandless line derived from ‘Liaomian 7’had significantly more protein (489.6 g/kg), and that from H237 had significantly more oil (362.4 g/kg) and had the largest oil index (2.70 g) and protein index (3.03 g). The gossypol content of seed in dominant glandless lines in Upland cotton was very low (<0.04 g/kg). Therefore, it is suggested that the glandless gene can play an important role in breeding glandless or low seed‐gossypol Upland cotton cultivars.     

陆地棉早熟基因来源的遗传分析

棉花早熟性相关的性状多为复杂的数量性状,是由多个基因和环境共同作用的结果,其遗传基础研究比较困难。利用连锁作图和关联分析方法,对目标性状进行基因定位,找出与性状相关联的位点,为解析复杂性状的基因来源提供了新的手段。本文分别以早熟亲本新陆早8号和新陆早10号为母本,以陆地棉标准系TM-1为父本构建F₂作图群体,利用在亲本间筛选出的多态性SSR引物,通过JoinMap 3.0软件构建了2张遗传图谱,以Win QTLCart 2.5复合区间作图法在F₂~F_2:3中定位到控制全生育期、苗期、蕾期、花铃期和霜前铃数等早熟性相关性状的37个QTL。控制早熟性的有利等位基因多来自早熟祖先611波和金字棉。多数性状在两类材料中由不同的基因控制,且以加性遗传为主。在由43个陆地棉品种材料构成的自然群体中通过关联分析检测到54个与这些早熟性相关性状极显著关联的位点。研究表明连锁作图和关联分析的检测结果具有较高的可比性。本研究为早熟陆地棉聚合改良以及分子标记辅助育种打下了基础。