田间条件下海岛棉和陆地棉花铃期叶片光保护的机制

研究海岛棉(Gossypium barbadense)和陆地棉(G. hirsutum)两个棉花栽培种的光合作用特性, 探讨两个栽培种光合机构的光抑制以及防御保护机制, 以期为新疆棉花高光效品种选育和高产高效栽培实践提供理论基础。在新疆生态气候条件下, 系统测定了海岛棉和陆地棉的叶片运动、叶片接受光量子通量密度(PFD)、叶片温度、叶绿素荧光参数、气体交换参数和光呼吸速率的日变化。研究结果表明: 陆地棉叶片的“横向日性”较强而海岛棉较弱, 导致海岛棉叶片接受PFD较低, 但其叶片温度较高。海岛棉叶片的光合速率和气孔导度均显著低于陆地棉。在8:00-10:00 (北京时间, 下同)海岛棉叶片的光呼吸速率略低于陆地棉, 其余时间段海岛棉和陆地棉叶片的光呼吸速率相似。不同栽培种间, 叶片的最大光化学效率和实际光化学效率的日变化均无明显差异。除14:00-16:00以外, 海岛棉叶片的表观电子传递速率和光化学猝灭系数均显著低于陆地棉。8:00以后, 海岛棉叶片的非光化学猝灭显著高于陆地棉。因此, 在新疆生态气候条件下, 海岛棉和陆地棉叶片“横向日性”运动能力和气孔导度的差异导致叶片所处的光温环境不同, 同时造成海岛棉叶片的碳同化能力较低。为阻止光合电子传递链的过度还原, 减轻光合机构的光抑制, 陆地棉叶片主要通过光合机构的电子流途径耗散激发能, 而海岛棉叶片通过热耗散途径和相对较高的光呼吸能力来耗散激发能。     

棉属二倍体野生棉与四倍体栽培棉种间杂交的胚珠培养

用棉属二倍体野生种与四倍体栽培种陆地棉杂交及四倍体栽培种海岛棉、陆地棉与二倍体栽培种亚洲棉杂交,以陆地棉自交作对照。将杂交和自交授粉后2天(部分材料为1天)的胚珠在液体培养基上进行飘浮静置暗培养。培养50—70天,7个杂交组合及2个自交品种的胚珠均获得一定频率的胚(包括成熟和不成熟胚)及成熟胚萌发的苗。其中陆地棉与澳洲野生棉、阿拉伯棉、亚洲棉、海岛棉与亚洲棉等4个杂交组合已得到杂种一代植珠。试验结果表明,同一组合的胚珠,在不同的培养基上获得胚的频率和胚萌发率有明显差异;不同组合的胚珠,在同一培养基上培养的结果也不一致。陆地棉X亚洲棉、海岛棉×亚洲棉两个组合授粉后1天的胚珠培养也获得一定频率的胚发育。     

用RAPD标记评估我国棉花品种遗传多样性

利用ＲＡＰＤ标记对１７个不同来源的我国棉花品种（系）进行遗传多样性评估。２００个随机引物扩增出１１３条多态性片段。１７个品种（系）依据染色体组的不同可以分为３大类。它们之间遗传相似性系数从０．２０００到０．８４５１。３个大面积推广品种鄂荆１号,中棉所１２号和苏棉３号遗传基础十分相近。陆地棉与阔叶棉杂交产生的野生种质系７５８１,与其他陆地棉品种（系）遗传差异显著。不同育种单位在育种过程中种质使用具有     

陆地棉×比克氏棉育成种质系的同工酶和RAPD分析

为了从分子水平上检验野生棉遗传特性向陆地棉转育的结果以及育成种质之间的遗传差异,通过等电聚焦电泳和RAPD技术,对来自科遗181陆地棉品系与野生比克氏棉杂交后代的6个遗传稳定的不同种质系及其亲本的过氧化物酶同工酶图谱和DNA指纹图谱进行了分析。结果如下（1）6个种质系的基本酶谱特征均倾向于陆地棉亲本,但在其中2个种质系的过氧化物酶图谱中,观察到各具有1条等电点值（PI）为4.85的野生亲本的特征带;（2）DNA指纹图谱的分析表明,不同种质系之间在基因组水平上具有高度的异质性。并且在OPO10和OPO112个引物的扩增图谱中观察到4个育成种质系具有野生比克氏棉亲本的特征带。     

棉花胚珠中的miRNA调控

正棉花是世界上最重要的经济作物之一,棉花胚珠表皮细胞特化形成的超长表皮毛即为棉纤维[1,2].棉纤维是人类用以遮身蔽体、御寒保暖的衣物之源.棉花属于锦葵科棉属,共有4个栽培种,即陆地棉(Gossypium hisutum)、海岛棉(Gossypium barbadence)、亚洲棉(Gossypium arboreum)和草棉(Gossypium herbaceum).具有AADD异源四倍体基因组的陆地棉是世界上栽培面积最广的品种.陆地棉的A二倍体基因组起源于草棉(A_1)和亚洲棉(A_2)的共同祖先A_0(已灭绝)[3].草棉和亚洲棉具有的基因组和功能基因的特性,是陆地棉性状的重要遗传基础.     

海岛棉与陆地棉叶绿素含量变化的差异研究

以5份陆地棉和4份海岛棉为材料,研究了整个发育进程中陆地棉和海岛棉叶绿素的变化规律之间的差异,结果显示：陆地棉与海岛棉的叶绿素a、叶绿素b和叶绿素a＋b各有不同动态变化规律,其叶绿素a/b在整个发育进程中的变化也有差异。海岛棉与陆地棉的叶绿素a变化趋势有较大差别,陆地棉的叶绿素a含量在6月18日（苗期）最高,峰值出现在8月6日,海岛棉峰值、最大值均在7月4日（现蕾期）;叶绿素b含量表现为陆地棉、海岛棉峰值均在8月6日（花铃期）,但海岛棉平均值高于陆地棉;陆地棉的叶绿素a＋b和叶绿素a曲线相似,海岛棉的叶绿素a＋b和叶绿素b曲线相似;陆地棉叶绿素a/b值表现苗期最大,然后迅速下降,海岛棉a/b值表现普遍低于陆地棉,其变化趋势为前期在7月4日出现峰值,然后下降再升高。实验说明陆地棉和海岛棉叶绿素的合成机制、调控机理可能不同。     

陆地棉与四个四倍体棉的遗传渐渗及QTL定位研究进展

陆地棉是棉属中最主要的一个栽培棉种,其产量占世界棉花总产的95％以上.我国对于陆地棉的引种、栽培和育种已有百年历史,在陆地棉不断改良的过程中,其遗传基础逐渐变得狭窄.为了拓宽陆地棉遗传基础,近十几年来,我国以及世界棉花基础研究和育种工作者通过有性杂交创建了棉花远缘杂交遗传群体和优异种质资源;与此同时,随着分子生物学的兴...     

长江、黄河流域两棉区陆地棉品种的遗传多样性比较研究

从300个随机引物中筛选到带型清晰且重复性强的41个多态性引物,用于长江、黄河流域两棉区的91陆地棉品种的RAPD标记分析。分析采用Jaccard‘s相似系数,使用NTSYS－pcl.80数据分析软件,非加权组平均法（UPGMA）聚类。来自长江流域棉区的23个陆地棉品种产生了84个多态性位点,品种之间的平均相似系数为0．631。而来自黄河流域棉区的68个陆地棉品种产生了96个多态性位点,品种之间的平均相似系数为0．632.两棉区品种的相似系数矩阵比较及成对相似系数分布的比较均表明,长江流域和黄河流域棉区陆地棉品种的遗传多样性水平相当。共同的基础种质资源、相同的育种目标及相近的育种方法和策略可能是造成两大棉区品种遗传多样性水平相当的重要因素。     

棉花种间杂交技术创新及育种程序的建立

创立的棉属种间杂交新方案对克服杂交不孕及F1不育性取得重大进展;获得了栽培种间(4n与2n)70个组合及陆地棉与14个野生棉种间大批量的高代种质资源,并已育成8个新品种,4个来自陆地棉×中棉,另外4个来自陆地棉与4种野生棉的杂种,为我国首次育成,其中石远321(冀棉24)为近年来国家区试中增产幅度最大的新品种,3年累计推广933.3×10³ hm².建成了有效的种间杂交育种体系.     

基于SSR标记的陆地棉早熟相关种质遗传多样性分析

丰富的遗传变异对于提高作物的环境适应性和遗传改良进度至关重要。为了解我国早熟陆地棉种质资源遗传多样性,本研究利用136对SSR引物对186份陆地棉材料(96份早熟陆地棉材料和90份中、晚熟陆地棉材料)进行了遗传多样性分析,共检测到等位基因变异355个,平均2.61个。在早熟棉材料中,有134对多态性SSR引物扩增出341个条带,平均2.54个;中、晚熟材料中有133对多态性SSR引物,扩增出345个条带,平均2.59个。早熟棉材料的位点多态性信息含量(PIC)、有效等位基因数(Ne)、基因型多样性(H')分别为0.684、3.994和1.361;中、晚熟棉材料的PIC、Ne、H'分别为0.668、3.852和1.343。早熟棉材料和中、晚熟棉材料的Jaccard相似性系数分别在0.349~0.935和0.270~0.907之间,平均为0.635、0.666。遗传相似性系数总体平均值接近,但早熟棉变化范围较中、晚熟棉小。用类平均法(UPGMA)进行聚类可将186份材料分成2个类群。总体上来看,供试材料遗传相似性系数较高,说明我国陆地棉早熟相关种质遗传基础狭窄。本研究结果为早熟棉育种亲本选配,早熟棉种质创新提供依据。     

盐胁迫对海岛棉和陆地棉幼苗生长及生理特性的影响

采用盆栽法,以海岛棉(Gossypium barbadense)品种新海21号、新海34号和陆地棉(G.hirsutum)品种新陆早50号、新陆早57号为材料,探讨了盐胁迫下海岛棉和陆地棉植株的生长、叶绿素含量、净光合速率、蒸腾速率、抗氧化酶活性、渗透调节物质及丙二醛含量变化的差异。结果显示,随着盐浓度的增加,4个供试品种幼苗的生长、叶绿素含量、净光合速率、蒸腾速率均呈不同程度的下降,而过氧化物酶、超氧化物歧化酶及可溶性糖含量随着盐浓度的增加呈先增后降的趋势,脯氨酸和丙二醛含量均上升。不同品种之间,新海21号和新海34号受胁迫的影响程度小于新陆早57号和新陆早50号。在0.6%Na Cl胁迫下,海岛棉和陆地棉品种均表现出较好的耐盐性。而0.8%和1.0%的Na Cl胁迫对4个供试品种的生长抑制作用大,导致新陆早57号和新陆早50号幼苗生长缓慢、叶面积小、干物质积累少甚至死苗。在较高浓度的盐胁迫下,棉花品种幼苗第1片真叶展开受到显著抑制,可以作为棉花耐盐品种的筛选指标。     

GENETIC DIVERSITY IN GOSSYPIUM HIRSUTUM AND THE ORIGIN OF UPLAND COTTON

Gossypium hirsutum has a large indigenous range encompassing most of Mesoamerica and the Caribbean, where it exhibits a diverse array of morphological forms spanning the wild-to-domesticated continuum. Modem, highly improved varieties (“Upland cotton”), which currently account for about 90% of world cotton commerce, are day-length neutral annuals derived from subtropical, perennial antecedents. To assess levels and patterns of genetic variation in the species and to elucidate the origin of Upland cotton, 538 accessions representing the full spectrum of morphological and geographical diversity were analyzed forallozyme variation at 50 loci. Levels of variation are modest overall but are low in Upland cotton. Relationships among accessions reflect pre-Columbian influences of aboriginal peoples and later European colonists superimposed on the preagricultural pattern. In contrast to expectations, two centers of diversity are evident, one in southern Mexico-Guatemala and the other in the Caribbean. Introgression of G. barbadense genes into G. hirsutum has been common in a broad area of sympatry in the Caribbean. The germplasm of present cultivars traces to Mexican highland stocks, which, in turn, were derived from material originally from southern Mexico and Guatemala. Despite the widespread belief that germplasm from several other species has been incorporated into modem Upland stocks through intentional breeding efforts, the 50 Upland cultivars examined contain no unique alleles, suggesting that retention of genes from transspecific sources has been minimal. The most recent infraspecific treatment, which recognizes seven races, does not adequately represent genetic relationships.     

棉花遗传多态性研究进展

从系谱分析、形态特征、生化及 DNA分子水平等方面分析了棉花遗传多样性的研究进展 .国内外的研究一致表明陆地棉品种间遗传多态性水平低 ,改进其遗传多样性是今后棉花遗传育种研究的重要内容 .加强对现有栽培品种、野生种质的研究利用和种质引进交流 ,多种育种技术综合运用和合理的植棉区域规划及多育种目标引导 ,是提高育成品种遗传多样性的重要途径 .并提出今后应加强棉花核心种质的研究和从基因组水平对棉花遗传多样性的研究     

我国陆地棉基础种质遗传多样性的SSR分子标记分析

利用398对BNL、JESPR、TMB等SSR引物,对不同亲本来源、不同选育时期、不同种植生态区的43份陆地棉基础种质进行了遗传多样性的SSR分子标记分析。扩增产物用8％的非变性聚丙烯酰胺凝胶检测,银染观察并照相。遗传多样性带型分析按位点多态信息量（PIC）,Shannon-weaver多样性指数（H^＋）等方法,利用NTSYSpc2．1软件计算品种间的遗传相似系数（Jaccard系数）,并用类平均法（UPGMA）进行聚类。结果表明所选择多态性引物分布在棉花基因组的第3、4、5、8、9、10、16、18、20、23号等染色体上,36对多态性引物在基础种质中扩增等位基因130个,其中多态性等位基因占80％,每个引物扩增等位基因2～8个,平均3．6个,PIC为0．278～0．865,平均0．62,基因型多样性（H^＋）为0．451～2．039,平均1．102,基础种质问SSR遗传相似系数平均为0．610,变幅为0．409～0．865,这说明所选基础种质基因组水平的多样性较丰富,变化范围大、代表性强。按品种不同选育时期来讲,第一、二、三期基础种质的SSR分子标记平均遗传相似系数分别是0．587、0．630、0．630,说明现代基础种质比早期基础种质在基因组水平的差异呈下降的趋势,可能是由于育种者偏重于使用优质高产性状的亲本品种,致使我国棉花的育种基础逐渐变窄。不同棉区基础种质SSR标记性状差异大,北部特早熟棉区基础种质间的SSR标记的多样性大于黄河、长江棉区,主要原因是长江、黄河棉区的育种过分强调高产、优质品种选育,品种间的差异变小;基础种质中的国内品种SSR相似系数（0．624）比引进品种（0.85）高,说明国内品种在遗传多样性上目前还没有超越国外品种。总之,我国棉花现代基础种质比早期基础种质的遗传多样性呈下降的趋势,黄河、长江主产棉区基础种质的遗传多样性还没有超过国外基础种质,品种间的遗传背景较为狭窄,还必须采用多种途径丰富我国棉花种质资源的遗传多样性。     

Genetic Diversity of Source Germplasm of Upland Cotton in China as Determined by SSR Marker Analysis

The genetic diversity of 43 sources of Upland cotton germplasm with different parental origins, breeding periods, and ecological growing areas in China were studied on the basis of simple sequence repeat (SSR) markers. A total of 130 gene alleles with 80% polymorphism were detected from 36 SSR primers. The number of alleles per primer ranged from two to eight with an average of 3.6. The polymorphism information content (PIC) range was 0.278-0.865, with an average of 0.62. The average genotype diversity index (H') was 1.102, the highest was 2.039 and the lowest was 0.451. The average coefficient of the genetic similarity of SSR markers among source germplasm was 0.610, ranging from 0.409 to 0.865. These indicated that the genetic diversity at the genomic level of the selected source germplasm was rich, and was representative of the diversity of the germplasms, in general. The diversity at the genome level of the base germplasm from the second and third breeding periods was decreased compared to that of the first period, indicating that the cotton genetic background in China became narrow gradually. The diversity of SSR markers among the base germplasm from early maturity cotton growing areas in the north was higher than those from the Huanghe and Yangtze growing areas. The molecular marker genetic similarity index of the domestic varieties was higher than that in the introduced varieties, which indicates that the genetic diversity in domestic cultivars was lower than that in the introduced varieties. This study gives an overview of the genetic diversity of the cotton germplasm base in China, and provides a guide for breeders to develop new cultivars efficiently.     

Breeding Potential of Introgression Lines Developed from Interspecific Crossing between Upland Cotton (Gossypium hirsutum) and Gossypium barbadense: Heterosis,Combining Ability and Genetic Effects

Upland cotton (Gossypium hirstum L.), which produces more than 95% of the world natural cotton fibers, has a narrow genetic base which hinders progress in cotton breeding. Introducing germplasm from exotic sources especially from another cultivated tetraploid G. barbadense L. can broaden the genetic base of Upland cotton. However, the breeding potential of introgression lines (ILs) in Upland cotton with G. barbadense germplasm integration has not been well addressed. This study involved six ILs developed from an interspecific crossing and backcrossing between Upland cotton and G. barbadense and represented one of the first studies to investigate breeding potentials of a set of ILs using a full diallel analysis. High mid-parent heterosis was detected in several hybrids between ILs and a commercial cultivar, which also out-yielded the high-yielding cultivar parent in F₁, F₂ and F₃ generations. A further analysis indicated that general ability (GCA) variance was predominant for all the traits, while specific combining ability (SCA) variance was either non-existent or much lower than GCA. The estimated GCA effects and predicted additive effects for parents in each trait were positively correlated (at P<0.01). Furthermore, GCA and additive effects for each trait were also positively correlated among generations (at P<0.05), suggesting that F₂ and F₃ generations can be used as a proxy to F₁ in analyzing combining abilities and estimating genetic parameters. In addition, differences between reciprocal crosses in F₁ and F₂ were not significant for yield, yield components and fiber quality traits. But maternal effects appeared to be present for seed oil and protein contents in F₃. This study identified introgression lines as good general combiners for yield and fiber quality improvement and hybrids with high heterotic vigor in yield, and therefore provided useful information for further utilization of introgression lines in cotton breeding.     

中国30个陆地棉主栽品种的SSR指纹图谱

利用SSR分子标记技术,对中国不同生态棉区曾经或正在种植的主要来源于岱字棉、斯字棉、福字棉、乌干达棉的30个陆地棉主栽品种进行了DNA指纹分析。从1 803对SSR引物中筛选到重复性好、多态性丰富的20对核心引物。这些引物分属棉花15条染色体,共检测到116个等位基因,平均每对引物5.8个;PIC值范围为0.384~0.900,平均为0.716;MI值范围为1.152~9.000,平均为4.374。30个品种中有4个品种具有各自的特异引物,可将其与其它26个品种区分开,其它26个品种可利用至少2对引物组合进行区分。为更方便、准确地鉴定各品种,构建了30个品种20对核心引物的十进制数字指纹代码。该研究为陆地棉的品种鉴定和纯度检测、新品种权益保护以及标准DNA指纹库构建提供了重要依据。     

Genomic divergence in cotton germplasm related to maturity and heterosis

Commercial varieties of upland cotton(Gossypium hirsutum) have undergone extensive breeding for agronomic traits, such as fiber quality, disease resistance,and yield. Cotton breeding programs have widely used Chinese upland cotton source germplasm(CUCSG) with excellent agronomic traits. A better understanding of the genetic diversity and genomic characteristics of these accessions could accelerate the identification of desirable alleles. Here, we analyzed 10,522 high-quality singlenucleotide polymorphisms(SNP) with the CottonSNP63 K microarray in 137 cotton accessions(including 12 hybrids of upland cotton). These data were used to investigate the genetic diversity, population structure,and genomic characteristics of each population and the contribution of these loci to heterosis. Three subgroups were identified, in agreement with their knownpedigrees, geographical distributions, and times since introduction. For each group, we identified lineagespecific genomic divergence regions, which potentially harbor key alleles that determine the characteristics of each group, such as early maturity-related loci. Investigation of the distribution of heterozygous loci, among 12 commercial cotton hybrids, revealed a potential role for these regions in heterosis. Our study provides insight into the population structure of upland cotton germplasm. Furthermore, the overlap between lineagespecific regions and heterozygous loci, in the high-yield hybrids, suggests a role for these regions in cotton heterosis.     

Resequencing core accessions of a pedigree identifies derivation of genomic segments and key agronomic trait loci during cotton improvement

Upland cotton (Gossypium hirsutum) is the world's largest source of natural fibre and dominates the global textile industry. Hybrid cotton varieties exhibit strong heterosis that confers high fibre yields, yet the genome‐wide effects of artificial selection that have influenced Upland cotton during its breeding history are poorly understood. Here, we resequenced Upland cotton genomes and constructed a variation map of an intact breeding pedigree comprising seven elite and 19 backbone parents. Compared to wild accessions, the 26 pedigree accessions underwent strong artificial selection during domestication that has resulted in reduced genetic diversity but stronger linkage disequilibrium and higher extents of selective sweeps. In contrast to the backbone parents, the elite parents have acquired significantly improved agronomic traits, with an especially pronounced increase in the lint percentage. Notably, identify by descent (IBD) tracking revealed that the elite parents inherited abundant beneficial trait segments and loci from the backbone parents and our combined analyses led to the identification of a core genomic segment which was inherited in the elite lines from the parents Zhong 7263 and Ejing 1 and that was strongly associated with lint percentage. Additionally, SNP correlation analysis of this core segment showed that a non‐synonymous SNP (A‐to‐G) site in a gene encoding the cell wall‐associated receptor‐like kinase 3 (GhWAKL3) protein was highly correlated with increased lint percentage. Our results substantially increase the valuable genomics resources available for future genetic and functional genomics studies of cotton and reveal insights that will facilitate yield increases in the molecular breeding of cotton.