Effects on Agronomic Traits of M_1 by Pollen of Upland Cotton Irradiated by ^(60)Co-γ Ray

[Objective] The aim was to provide reference for research on radiation and breeding of cotton pollen through irradiating common ripe pollen grain of upland cotton by 60Co-γ Ray of varied doses. [Method] Ripe pollen grains of upland cotton were irradiated by 60Co-γ Ray with doses of 5, 10, 15, and 20 Gy, respectively, to learn radiation effect and select appropriate dose. [Result] Most properties of M1 obviously showed variation when dose was over 10 Gy; vitality, growth, and fertility were greatly inhibited when dose was 15 Gy which was almost semi-lethal concentration, and variation species were richest at the same time, which provided materi- als for practical breeding. [Conclusion] 60Co-γ Ray of 15 Gy is more suitable for mutagenesis research on ripe pollen grains of upland cotton.

Genetic Diversity,Population Structure,and Genome-Wide Association Study of Seven Agronomic Traits in 273 Diverse Upload Cotton Accessions

Upland cotton(Gossypium hirsutum)is the most important plant producing natural fibers for the textile industry.In this study,we first investigated the phenotypic variation of seven agronomic traits of 273 diverse cotton accessions in the years 2017 and 2018,which were from 18 geographical regions.We found large variations among the traits in different geographical regions and only half of the traits in either years 2017 or 2018 followed a normal distribution.We then genotyped the collection with 81,612 high quality SNPs.Phylogenetic tree and population structure revealed a diverse genetic structure of the core collection,and geographical diversification was an important factor,but account for part of the variances of genetic diversification.We then performed genome-wide association study for the seven traits in the years 2017 and 2018,and the average values of each trait in the two years,respectively.We identified a total of 19 significant marker-trait associations and found that Pollen Ole e 1 allergen/extension could be the candidate gene associated with the fall-off cotton bolls from the last three branches.In addition,large variations were observed for the heritability of traits in the years 2017 and 2018.These results provide new potential candidate genes for further functional validation,which could be useful for genetic improvement and breeding of new cotton cultivars with better agronomic performances.

Genetic variability for yield and fiber related traits in genetically modified cotton

Background:Cotton(Gossypium hirsutum L.)is grown for fiber and oil purposes in tropical and sub-tropical areas of the world.Pakistan is the 4th largest producer of cotton.It has a significant contribution in the GDP of Pakistan.Therefore,the present study was performed to assess the genetic variations and genetic diversity of yield and fiber quality traits in cotton and to analyze the associations present among them.Results:Analysis of variance exhibited significant variation for all studied traits except total number of nodes and the height to node ratio.The phenotypic coefficient of variation was higher than the genotypic coefficient of variation for all studied traits.Plant height,monopodial branches,total number of bolls,lint index,seed index,and seed cotton yield displayed high heritabilities in a broad sense with maximum genetic advanee.Correlation analysis revealed that seed cotton yield had a significant positive association with plant height,the nu mber of monopodial branches,the nu mber of sympodia I branches,ginning outturn(GOT),the number of bolls,seed per boll,seed index,uniformity index,the number of sympodial branches,reflectance,and seed index at the genotypic level while a significant positive relationship was observed with plant height,the number of sympodial branches,boll number,and GOT.Plant height,monopodial branches,GOT,boll weight,seeds per boll,and short fiber index exerted direct positive effects on seed cotton yield.The first 6 principal component analysis(PCs)out of the total fourteen PCs displayed eigenvalues(>1)and had maximum share to total variability(82.79%).The attributes that had maximum share to total divergence in eluded plant height,uniformity index,the nu mber of sympodial branches,seed per boll,GOT,seed cotton yield,and short fiber index.Conclusion:The genotype AA-802,IUB-13,FH-159,FH-458,and CIM-595 were genetically diverse for most of the yield and fiber quality traits and could be utilized for the selection of better performing genotypes for further improvement.

Heritability and correlation analysis of morphological and yield traits in genetically modified cotton

Background:Cotton is known for fiber extraction and it is grown in tropical and sub-tropical areas of the world due to having hot weather.Cotton crop has a significant role in GDP of Pakistan.Therefore,the two-years research was conducted to estimate heritability and association among various yield contributing parameters of cotton,i.e.,plant height,number of bolls per plant,number of sympodial branches per plant,seed cotton yield,boll weight,seed index,ginning outturn(GOT),fiber length,fiber strength,and fiber fineness.Results:Association analysis revealed that seed cotton yield had a significant positive correlation with plant height,number of bolls per plant,number of sympodial branches per plant,GOT,staple length and fiber strength.Staple length and fiber strength were negatively linked with each other.Estimates of heritability were high for all of the traits except the number of sympodial branches per plant and boll weight.Conclusion:The parent IUB-222 was found to be the best for plant height,the number of bolls per plant,boll weight,GOT,seed cotton yield,and seed index.The genotypes namely,NIAB-414 and VH-367 were identified as the best parents for fiber length,strength,and fineness.Among the crosses NIAB-414×IUB-222 was the best for the number of bolls per plant,seed index,seed cotton yield and fiber fineness,whereas,the cross of NIAB-414×CIM-632 was good for plant height.The combination of A555×CIM-632 was the best for the number of sympodial branches per plant,boll weight,fiber length,and strength,and VH-367×CIM-632 proved the best for GOT.

Construction of a linkage map and QTL mapping for fiber quality traits in upland cotton (Gossypium hirsutum L.)

With the development in spinning technology, the improvement of cotton fiber quality is becoming more and more important. The main objective of this research was to construct a high-density genetic linkage map to facilitate marker assisted selection for fiber quality traits in upland cotton (Gossypium hirsutum L.). A genetic linkage map comprising 421 loci and covering 3814.3 cM, accounting for approximately 73.35% of the cotton genome, was constructed using an F2 population derived from cross GX1135 (P 1 )×GX100-2 (P 2 ). Forty-four of 49 linkage groups were assigned to the 26 chromosomes. Fiber quality traits were investigated in F2 population sampled from individuals, and in F2:3 , and F2:4 generations sampled by lines from two sites and one respectively, and each followed a randomized complete block design with two replications. Thirty-nine quantitative trait loci were detected for five fiber quality traits with data from single environments (separate analysis each): 12 for fiber length, five for fiber uniformity, nine for fiber strength, seven for fiber elongation, and six for fiber micronaire, whereas 15 QTLs were found in combined analysis (data from means of different environments in F2:3 generation). Among these QTLs, qFL-chr5-2 and qFL-chr14-2 for fiber length were detected simultaneously in three generations (four environments) and verified further by combined analysis, and these QTLs should be useful for marker assisted selection to improve fiber quality in upland cotton.

Molecular Tagging and Mapping of Quantitative Trait Loci for Lint Percentage and Morphological Marker Genes in Upland Cotton

Using 219 F2 Individuals developed by crossing the genetic standard line TM-1 and the multiple dominant marker line T586 In Gossyplum hirsutum L., a genetic linkage map with 19 linkage groups was constructed based on simple sequence repeat （SSR） markers. Compared with our tetraploid backboned molecular genetic map from a （TM-1xHal 7124）xTM-1 BC1 population, 17 of the 19 I｜nkage groups were combined and anchored to 12 chromosomes （sub-genomes）. Of these groups, four morphological marker genes In T586 had been mapped Into the molecular linkage map. Meanwhile, three quantitative trait loci for lint percentage were tagged and mapped separately on the A03 linkage group and chromosome 6.

陆地棉抗虫与抗草甘膦基因的分子聚合及经济性状相关分析

培育抗棉铃虫兼抗草甘膦的棉花,可以同步提高品种的抗虫与抗除草剂能力,降低植棉的除虫、除草用工成本,提升植棉综合经济效益。本研究利用自育的高产优质陆地棉品系、国产转Bt基因抗虫棉品系以及转GR79+GAT基因的抗草甘膦陆地棉品系为杂交亲本,配置复交组合。在繁殖的复交分离群体后代,通过在苗床喷洒0.2%草甘膦,去除不抗草甘膦棉苗;并在大田不防治棉铃虫的条件下,筛选抗虫棉株。而后在实验室利用特异引物对抗虫基因与抗草甘膦基因进行分子跟踪检测,将同时具有Bt基因与GR79+GAT基因的单株繁殖成株系,经大田筛选获得9个抗虫兼抗草甘膦的优良品系。然后对育成品系进行产量比较试验,结果显示,其中品系BG-6不但实现了抗虫与抗草甘膦基因的聚合,而且该品系的皮棉产量水平较高、纤维品质表现良好:纤维长度达30.9 cm、比强度30.1 cN tex^(-1)、马克隆值4.9。对产量性状与纤维品质性状相关分析显示,只有衣分与棉纤维整齐度呈极显著负相关(r=-0.838**),其他产量性状与纤维品质性状均不存在显著相关性。文章最后得出结论:在复合杂交组合的分离后代,通过在苗床喷洒草甘膦筛选抗性棉苗,再结合大田不治虫筛选抗虫单株;而后在室内对2种抗性基因进行PCR分子跟踪检测,再在大田对产量性状与品质性状进行系统选育,可实现抗虫与抗草甘膦基因以及高产与优质性状的多元聚合。

南疆陆地棉农艺性状与皮棉产量性状的遗传贡献及决策系数分析

研究陆地棉亲本及F1组合农艺性状与皮棉产量性状的遗传,为育种工作者对某些性状的选择和改良提供参考依据。采用加性-显性及其与环境互作的遗传模型对130个陆地棉品种(系)及其206个F1组合的4个农艺性状和4个产量性状的观察结果进行了遗传贡献分析和决策系数分析。分析结果显示,这些性状具有丰富的遗传多样性,亲本的8个性状的变异系数在5.54%~50.83%之间, F1组合则在3.96%~55.87%之间。农艺性状(除第一果枝节位对衣分外)对产量性状的加性贡献率均达到极显著水平(贡献率在4%~100%),五瓣铃率和株高对单株铃数和铃重的加性贡献率和显性×环境互作贡献率均达0.01以上的正向极显著水平。遗传效应中受加性效应控制有第一果枝高度、株高、五瓣铃率、铃重和衣分,其中衣分为最大。株高除加性效应较小外,其显性效应、加性×环境互作效应、显性×环境互作效应和互作广义遗传率均为最大。确定了提高陆地棉杂交种后代单株皮棉产量的主要决策性状和限制性状。陆地棉变异系数幅度较大;五瓣铃率和株高对提高单株铃数和铃重起着更为重要的作用;单株铃数、铃重和衣分是提高单株皮棉产量的主要决策性状。

235份陆地棉表型性状遗传多样性分析

本研究利用235份陆地棉种质资源材料,对棉花株型、生育期、产量性状展开研究。通过对16个表型性状进行遗传多样性分析、相关性分析、主成分分析、聚类分析及隶属函数计算得到综合评价值,对陆地棉种质资源进行综合评价。结果表明,235份陆地棉群体具有丰富的遗传多样性,性状遗传多样性指数为1.969~2.107。不同农艺性状指标通过主成分分析得到6个独立的因子,主效因子贡献率为6.20%~23.80%,累计贡献率为81.573%。依据特点分为产量相关因子、棉花生长结构因子、早熟相关性状因子等因子。聚类分析按照整体性状分为Ⅳ类,第Ⅰ类群占比15%,株高较高,株型松散;第Ⅱ类群占比27%,株型较为紧凑,生育期较短,产量相对较高,适合新疆地区的机械采收;第Ⅲ类群占比24%,综合表现最差;第Ⅳ类群占比34%,特点为生育期较长,产量一般。通过计算综合评价值并与表型性状进行相关性分析得出,综合评价值与株高、单铃质量、衣分、单铃皮棉质量和有效铃数等指标呈显著正相关。最后,利用线性回归方程逐步回归得到株高、有效铃数、中部果枝长度、落叶等级、单铃质量、有效果枝数、第一果枝高度、全生育期和中部果枝夹角等9个表型性状,这9个表型性状能够综合评价陆地棉的遗传多样性。本研究结果可为陆地棉种质资源的合理利用及亲本选育提供理论依据。

陆地棉资源主要产量和纤维品质性状的遗传多样性分析研究

为了提高棉花种质资源的利用效率、增加骨干亲本的遗传多样性,对114份资源材料进行遗传多样性分析、相关性分析、主成分分析和聚类分析。衣分、单铃重和马克隆值的变异系数较大,整齐度的变异系数最小;子指的遗传多样性指数最大,伸长率的遗传多样性指数最小;主成分分析的前3个因子累计贡献率达到83.91%;单铃重与衣分和子指均为极显著正相关,衣分与子指为极显著负相关,纤维品质性状之间均为正相关关系,子指与纤维品质主要表现为负相关,单铃重和衣分与纤维品质表现为显著的正相关;聚类分析将供试材料分为3个大群,第Ⅰ大群主要为彩色棉品种;第Ⅱ大群为纤维品质优异、产量性状一般的材料;第Ⅲ大群的产量和纤维品质综合表现较好。本研究明确了各类材料的典型特征,为材料的高效利用和亲本选择提供一定参考。

陆地棉种质资源遗传多样性分析及初级核心种质构建

旨在评价陆地棉种质资源的遗传多样性和筛选代表性种质,为科学评价和高效利用陆地棉种质资源提供理论依据。基于367份陆地棉种质的SNP标记及其中353份种质的表型数据分别分析其遗传多样性、构建系统进化树及初级核心种质,并对初级核心种质的构建效果进行评价。结果显示,原始陆地棉群体SNP位点多态性信息含量为0.24,各表型性状的遗传多样性指数均接近或大于2.00,与前人研究结果相近。基于SNP标记可以将供试群体划分为3个类群,构建了73份基因型初级核心种质,初级核心种质的Nei′s遗传多样性指数、多态性信息含量等指标数值大于原始种质。基于表型数据可将供试群体划分为3个类群,各性状均值呈第Ⅰ类群最小、第Ⅱ类群居中、第Ⅲ类群最大的趋势。构建了含70份材料的表型初级核心种质,各性状均值较原始种质的差异均不显著,极差、遗传多样性指数与原始种质相近,变异系数均高于原始种质。基于SNP标记构建的初级核心种质和基于表型数据构建的初级核心种质有15份重合,这些种质多为基因型第Ⅱ类群和表型第Ⅱ类群。以上结果表明,陆地棉种质资源基因型遗传多样性较低,但表型变异丰富、遗传多样性较高。本研究构建的基因型和表型初级核心种质遗传多样性代表性较好,可作为典型种质进行保存和利用。

陆地棉棉籽主要品质性状与农艺性状的遗传变异分析

为通过农艺性状、纤维性状预测棉籽品质,以27份陆地棉为试验材料,对其10个农艺性状、3个种子品质性状和5个纤维品质性状连续2年进行鉴定,利用方差分析、相关性分析、主成分分析和聚类分析对农艺性状、纤维性状与种子品质性状间的关系进行解析。结果表明,油分含量与衣分呈极显著负相关,与果枝数呈极显著正相关;棉酚含量与叶面积呈显著负相关。主成分分析提取出6个主成分,累计贡献率为78.755%,其中第3主成分和第5主成分为棉籽副产品因子,贡献率为20.470%。综合分析得出果枝数、衣分和叶面积与棉籽副产品关系密切。以上结果为深入研究农艺性状与棉籽油分、蛋白质和棉酚的内在关系奠定了基础,为选育特种棉提供了理论参考。

乙烯利催熟对优质陆地棉纤维品质的影响

提高陆地棉纤维品质是棉花育种的目标之一,筛选性状优良、遗传稳定且对乙烯利不敏感的基因型材料,可为棉花育种提供方向,并可提高育种效率。本研究采用两因素随机区组设计,对242个纤维品质优异的陆地棉品系开展喷施乙烯利试验,获得所选陆地棉品系的5个纤维品质性状(纤维长度、整齐度、马克隆值、比强度、伸长率)试验数据,对这些性状进行方差分析,估算这些品系的基因型效应值,并对每个品系纤维品质性状乙烯利喷施与否的效应进行分析。结果表明,棉纤维的这5个品质性状都具有极显著的基因型效应,且在表型方差的占比中遗传方差的比例大于误差方差,表明这5个品质性状受遗传因素的作用较大;同时基因型与处理互作达到极显著水平,表明在乙烯利喷施与否的两个不同处理下,这些品系的5个纤维品质性状对乙烯利的敏感性不同。

陆地棉种子性状直接效应和母体效应的遗传分析

采用二倍体种子遗传模型及其分析方法,分析了陆地棉（Gossypium hirsutum L.) 5个品种及其配制的F_1、F_2和正反回交一代（BC_1;、BC_2、RBC_1和RBC_2）世代籽指、种仁率、容重和油分4个种子性状的直接效应、母体效应和细胞质效应。分析结果表明,4个棉子性状的遗传均以母体效应为主,种子直接遗传效应作用较小。各性状的直接效应与母体效应的协方差不显著。通过母体植株的遗传表现对这些性状选择更为有效。可以根据籽指小和容重大等性状母体植株的遗传表现间接选择高油分材料。母体加性效应大的亲本,其杂种后代的母体加性效应总值一般也较大。

陆地棉主要经济性状的遗传相关及遗传差异

对陆地棉 96个品种 (系 )的 1 3个性状进行了方差、遗传相关、系统聚类分析 ,结果表明 :各性状材料间差异显著 ,性状间存在不同程度的遗传相关 ;产量性状间相关度高 ;产量与纤维品质间相关性较低 ,与纤维强度几乎无相关性。根据遗传距离对参试材料进行系统聚类 ,聚为五类 ,第四类群材料丰产优质 。

陆地棉F_2纤维品质性状杂种优势的遗传分析

本研究根据加性─显性与环境互作的遗传模型，分析了陆地棉１０个杂交亲本和２０个Ｆ１五个纤维品质性状的两年试验资料，估算各项遗传方差分量和成对性状间各项遗传效应的相关，预测了不同年份Ｆ２杂种优势的遗传表现。各纤维品质性状主要受加性效应的影响。其中纤维长度、纤维强度和麦克隆值３个性状还受到基因型×环境互作效应的影响。基因型×环境互作效应对纤维整齐度和纤维伸长率两个性状影响均不显著。遗传相关分析表明，杂交后代皮棉产量与纤维长度、纤维整齐度、纤维伸长率和纤维细度间可进行同步改良，皮棉产量与纤维强度同步改良较为困难。杂种早代皮棉产量高的组合其纤维强度也较好。Ｆ２纤维品质性状杂种优势的均值一般较小。此外还分析了组合纤维长度、纤维强度和麦克隆值杂种优势在不同环境中的表现。

陆地棉棉铃性状的遗传效应分析

根据加性 显性 母体效应遗传模型,分析了 6个陆地棉亲本及其按完全双列杂交法配制的 30个F1 的铃重、单株铃数、铃体积、铃容重、单铃种子数、子指、衣指、衣分、铃纵经、铃横经、铃形指数和铃室数共 12个棉铃性状的遗传方差分量以及铃重与其它棉铃性状之间的各项遗传相关。结果表明,铃重和铃容重的加性方差和显性方差均达显著水平;但显性方差明显大于加性方差;铃体积、铃纵径、铃横径和铃形指数的加性方差和显性方差均达显著水平,且两者差异不大;子指、衣指、单铃种子数及衣分等性状均存在显著的母体效应。此外,衣分和衣指的加性方差亦达极显著水平;单铃种子数显性方差达极显著水平;子指的加性和显性方差均不显著;单株铃数的加性和显性效应均达显著水平;衣指、子指、铃体积等性状与铃重间都存在显著的加性相关;而单株铃数与铃重则呈极显著加性负相关;单株铃数、单铃种子数、铃容重、铃体积、铃横径等性状与铃重之间都存在极显著的显性正相关。

陆地棉纤维品质与主要农艺性状的相关性分析

为了解陆地棉纤维品质与主要农艺性状之间的关系,对中571和中棉所49杂交F5群体材料的5个农艺性状和3个品质性状进行了相关性分析。结果表明,各性状间存在一定的相关性,在通径分析中,对纤维上半部平均长度的直接贡献大小为衣分>单铃质量>株高>果枝数>果枝节位,对纤维断裂比强度的直接贡献大小为衣分>单铃质量>果枝数>株高>果枝节位,对马克隆值的直接贡献大小为衣分>单铃质量>果枝数>果枝节位>株高。回归分析结果表明,株高、果枝数、单铃质量和衣分决定了纤维上半部平均长度0.197 5的变异,株高、果枝数、单铃质量和衣分决定了纤维断裂比强度0.221 4的变异,果枝节位、果枝数、单铃质量和衣分决定了马克隆值0.471 8的变异。主成分3对棉花纤维上半部平均长度、纤维断裂比强度、马克隆值的累积贡献率分别为68.590 3%、70.343 7%和70.421 7%。对于材料自身的特性而言,通过杂交来互补各品种特性是一种有效方法,可以在棉花品种选育中实现产量与品质的平衡。

陆地棉衣分差异群体产量及产量构成因素的QTL标记和定位

以衣分差异较大的陆地棉品种为材料,构建了包含188个F2单株的作图群体,应用6111对SSR引物对亲本进行了分子标记筛选,结果仅获得了123个多态性位点,其中88个位点构建了总长为666.7cM、平均距离为7.57cM的遗传图谱,覆盖棉花基因组的14.9%。通过复合区间作图法对F2单株和F2:3家系进行QTL检测,共鉴定出了18个控制产量及产量构成因素变异的QTLs,包括2个衣分QTLs、4个子棉产量QTLs、4个皮棉产量QTLs、2个衣指QTLs、3个单株铃数QTLs、2个铃重QTLs和1个子指QTL。解释的表型变异分别为6.9%～16.9%、5.6%～16.2%、4.8%～15.6%、7.7%～13.3%、8.2%～11.6%、6.1%～7%和6.6%。不同QTLs在相同染色体区段上的成簇分布表明与产量性状相关的基因可能紧密连锁或一因多效。产量及产量构成因素QTLs的遗传方式主要以显性和超显性效应为主。检测到的主效QTLs可以用于棉花产量及产量构成因素的分子标记辅助选择。

持续高温干旱年份陆地棉农艺和产量性状的遗传效应分析

本文采用NCⅡ交配设计方法,以9个陆地棉品种(系)配置16个杂交组合,利用加性—显性与环境互作的遗传模型(ADE模型),分析亲本和F1在2013年持续高温干旱条件下望江、九江2个环境下的农艺和产量性状,估算了各项遗传方差分量,分析了性状间各项遗传效应的相关性和各性状的杂种优势。结果表明,农艺和产量性状易受环境条件影响,子棉产量、皮棉产量、单株铃数和铃重的遗传主要受显性效应控制,衣分同时受加性和显性效应控制,子指主要受加性效应控制。遗传相关分析表明,子棉产量和皮棉产量与铃重和衣分呈显性正相关;铃重与衣分呈显性正相关,衣分与子指的加性和显性均为负相关。杂种优势分析表明,中棉所63的铃重、衣分、子指、子棉产量和皮棉产量的群体平均优势达极显著水平,其皮棉产量的杂种优势可以利用至F3。