【作者】 艾尼江；

【导师】 张天真；

【作者基本信息】 南京农业大学 ， 作物遗传育种， 2010， 博士

【摘要】 早熟种质资源是决定早熟相关性状的遗传资源。开展早熟种质资源研究是早熟棉育种工作的基础。在我国,随着金字棉的(king’s)引进和广泛利用,早熟陆地棉育种取得了突破性的进展；但同时也导致了早熟棉遗传基础的狭窄性,使得早熟陆地棉综合性状的改良效果不理想。目前,在美国、中国、澳大利亚、印度等棉花生产大国,遗传基础狭窄已成为棉花品种改良的主要障碍。因此,陆地棉的遗传多样性的改善和特异资源的创新,已成为今后棉花种质资源工作的重点。目前,应用常规育种手段提高早熟陆地棉产量难度愈来愈大；利用现代分子生物技术,对棉花熟性性状的遗传、QTL定位及品种遗传多样性进行研究显得极为重要。迄今为止,国内外学者对陆地棉早熟及其相关性状的QTL定位研究仍然很少。本文以早熟棉花品种为材料,研究了早熟性、产量、品质等性状的遗传、QTL定位、早熟性相关性状的关联分析以及不同生态棉区育成的早熟棉花品种的遗传多样性,为早熟陆地棉育种提供理论依据。针对43份早熟陆地棉品种来源、育成地区以及衍生系进行了分类,并对表型性状进行了综合比较。结果发现在长江流域环境中,新疆棉区育成品种的生育期延长,表现偏晚。伏前桃、秋桃数少于其它棉区品种；而伏桃数、总果枝数则相反。新疆棉区品种在品质上显著优于其它棉区品种。在西北内陆环境中,同其它棉区品种相比,新疆棉区品种表现早熟,伏前桃和伏桃数,总果枝、总铃、有效铃、霜前铃数增加,霜前籽、皮棉产量、霜前花率高。纤维强度和纺纱均匀性指数高。衍生系间相比,C42、611波表现早熟,其伏前桃、伏桃多于其它衍生系；岱字棉、乌干达衍生系的有效果枝数、总铃数高于其它衍生系；金字棉衍生系的霜前籽、皮棉产量、衣分高于其它衍生系；金字棉、塔什干、乌干达衍生系的铃重大于其它衍生系；岱字棉和乌干达衍生系的品质好于其它衍生系。经SSR标记检测,174对多态性引物把43份材料以品种的选育地区、亲本系谱或遗传基础划分为8类,聚类结果和系谱来源基本吻合。其中共检测到486个等位变异位点,平均每个标记检测到了2.75个多态位点,多态信息含量为0.331。虽然等位变异数目和基因多样性跨度较大,但平均值较低,反映了陆地棉遗传基础的狭窄性。在遗传多样性分析的基础上,利用TASSEL软件对棉花基因组内的连锁不平衡水平进行了分析。结果表明,棉花基因组内的连锁不平衡位点数目多,分布很不均匀。LD集中的区域主要在A11、D5、D12等染色体的个别标记上。所选的陆地棉中包含3个亚群体。在多个环境中共检测到了与12个性状相关联的位点数近390个,其中极显著关联的位点90个。多年多点综合分析中检测到了与12个性状极显著相关的关联位点30个。位于D9、A2、D2、D6染色体上的5个标记在多个环境及综合分析中检测到,分别与花铃期、生育期、果枝始节、霜前铃等性状相关联,说明这些标记位点存在相关性状的QTL。利用表型和基因型之间特定的等位变异关系,发掘了一批优异关联位点及其典型材料。含有标记NAU5467-1、NAU3519-2、NAU4048-1、NAU2687-2、BNL1317-2的等位变异明显缩短蕾期、花铃期、生育期；NAU5467-1、NAU3519-2降低果枝始节和果枝始节高度；NAU437-1、NAU1366-2、NAU3052-2、JESPR291-2、NAU5379-2及NAU462-1增加霜前铃、霜前籽、皮棉产量,这些等位变异的典型材料是新陆早10号和晋棉14号等,分别来自前苏联及金字棉衍生系。利用6个早、中、晚熟陆地棉品种(系)新陆早8、10号、宁早1号、苏棉12号、荆8891、TM-1,配制了6×(6-1)/2个杂交组合,利用两年三点的亲本和F1试验数据,应用作物数量性状QTL检测体系的主位点组加-显性及环境(ADE)遗传模型估计了亲本遗传组分、杂种Fl熟性以及霜前皮棉产量杂种优势的有利、不利位点。结果表明,苗期、蕾期、花铃期、生育期等熟性性状的主位点组的表型解释率为9.3-39.4(%),霜前皮棉产量主位点组解释率为36.7%。现蕾、吐絮、生育期阶段J=16位点加性效应值大于其它位点组,说明此位点在陆地棉早熟性状中起主要作用。早熟和中熟亲本现蕾期、花铃期、生育期基因型值和表型值普遍短于晚熟亲本,且具有较多的促早熟有利基因位点。在亲本间杂交组合霜前皮棉主位点组中,组合新陆早8号×荆8891聚合了所有有利位点；此外,多数组合杂合位点对霜前皮棉产量的贡献率大于纯合位点,杂种产量优势主要以杂合位点来表现,同时纯合位点也有贡献。本实验结果也说明了在早熟陆地棉区域开展育种时,以当地优良材料作为核心亲本,以加性效应较大、遗传率高的性状作为选择指标时,能够达到较理想的选择目的。用新陆早8、10号分别与TM-1杂交,构建F2群体(Pop1和pop2)以及F2:3家系。用SSR标记数据以复合区间作图法(CIM)构建了两张早熟陆地棉品种间的遗传图谱。总长分别为1284.88cM和598.14cM,各含有127和54个标记,分别覆盖棉花基因组的11.97%和25.7%,平均标记间距10.12cM和10.68cM。各由18和12条连锁群组成,其中pop1图谱中有3个连锁群未被定位到染色体上,而pop2图谱中所有连锁群均定到相应了的染色体上。利用两张遗传图谱分别对34个熟性、产量、品质等性状进行了QTL定位。经1000次测验,共检测到了61个显著性QTL。在D7染色体上发现了多个性状的QTL富集区,其中产量性状的4个QTL可在两个群体中检测到；分别位于A2和D7染色体上的生育期和霜前皮棉产量的QTL,在关联分析中同一条染色体的相近位置也能检测到,均有较好的稳定性。利用共有的桥梁标记整合了一张陆地棉品种间的遗传图谱。该图谱包含154个多态位点,总长1519.31cM、覆盖率为30.38%,两多态位点间的平均遗传距离为9.86cM。该图谱由3个连锁群和18条染色体组成。在染色体A2、A5、A6、A6/D6、A7/D、D1、D2、D7、D9上定到了熟性、产量、品质及农艺性状QTL。多数性状的富集区主要集中在D7、A6和A6/D6上。分别具有611波和金字棉遗传背景的两个新疆自育品种中早熟性由不同基因控制,且早熟性相关性状的基因以加性遗传为主。更多还原

【Abstract】 Early-maturing germplasms are important genetic resources in Upland cotton breeding. In China, with the introduction and utilization of King’s cotton, a breakthrough progress has been made in early-maturing breeding, yet it also narrowed the genetic diversity, leading to the bad efficiency in the improvement of overall traits. Today, the narrow genetic bases has been the bottleneck for cotton breeding in cotton growing countries including USA, China, Australia, India, etc, so it is important to create and diversify the cotton germplasms. Currently, It is more and more difficult to improve yield of early-maturing upland cotton by conventional breeding, therefore, studies on the inheritance, quantitative trait loci (QTL) mapping, and genetic diversity for maturity are needed based on modern molecular biotechnology. Few studies have been reported previously on QTL mapping for earliness and its related traits in upland cotton. In this study, on the base of the genetic diversity analysis of different early-maturing upland cottons, QTL for earliness, yield and fiber quality traits were identified, and the heredity of these traits as well as their association analysis were carried out in order to serve the early-maturing upland cotton breeding.Forty-three early-maturing upland cotton cultivars were classified and compared according to their parental origins, breeding sites and trait performance. The results showed that in Yangtze River Valley, compared to varieties developed in other cotton growing areas, Xinjiang cultivars matured late with growth stage elongated, better fiber quality, more hot-season bolls and fruit branches, but with less pre-hot season as well as autumn bolls. Whereas in Northwest Inland, Xinjiang cultivars matured early with more pre-hot season, hot season, effective, pre-frost and total bolls, increased fruit branches, pre-frost seed cotton and lint yield, higher rate of pre-frost cotton, and better fiber strength and spinning consistency index. Among varieties derived from different ancestors, C42 and 611Bo performed early-maturity and had more pre-hot season and hot-season bolls; Deltapine and Uganda derived lines had more effective fruit branches and total bolls, and better fiber quality; Kings derived lines had a higher pre-frost seed cotton yield, lint yield and lint percentage; furthermore, the Kings, Tashkan as well as Uganda derived lines showed greater boll weight than others. One hundred and seventy-four polymorphic primer pairs were used to divide the 43 cultivars into 8 clusters, consistent with the breeding region, pedigree and genetic bases of these cultivars. Four hundred and eighty-six allelic variations were detected with 2.75 polymorphic loci per primer pairs and the polymorphic information content (PIC) 0.331. Though the number of alleles revealed by SSR primers had a huge range, the average number per chromosome was at a low level, indicating the genetic basis of upland cotton was narrow.Based on analysis of genetic diversity among 43 varieties, the level of linkage disequilibrium (LD) within the whole cotton genome was analyzed using TASSEL software. Results showed that though the LD sites had a huge number, their distribution was not uniform within the cotton genome. LD sites were concentrated on individual markers at chromosome All, D5 and D12. Three hundred and ninety loci associated with 12 traits were detected across multiple environments, of which 90 were highly associated. In combined analysis, thirty highly associated loci were identified. Five markers on D9, A2, D2 and D6, which were associated with flowering, growth stage, first fruit branch node and pre-frost bolls, were detected in multiple environments and in combined analysis respectively, suggesting the existence of QTL in these regions. Based on the allelic variation relationship between genotypes and phenotypes, several trait-associated loci as well as elite materials were identified. Positive alleles adjacent to NAU5467-1, NAU3519-2, NAU4048-1, NAU2687-2 and BNL1317-2 obviously shortened budding, flowering and growth stages; positive alleles near NAU5467-1 and NAU3519-2 dropped the first fruit branch node and its height; while positive alleles close to NAU437-1, NAU1366-2, NAU3052-2, JESPR291-2, NAU5379-2 and NAU462-1 increased pre-frost bolls, pre-frost seed cotton yield and lint yield. These positive alleles were from elite materials XinluzaolO and Jinmian14, which were derived from the former Soviet Union and King’s cotton respectively.6×(6-1)/2 crosses were made with six early-, mid-and late-maturing upland varieties (Xinluzao8,10, Ningzaol, Sumian12, Jing8891, TM-1). Based on data of parents and F1 in three environments, the gentic components of parents, favorable and unfavorable loci for F1 maturity and pre-frost lint yield heterosis were estimated by QTL detection system (ADE genetic model). The results showed that the phenotypic variations explained by major loci groups for maturity and pre-frost lint yield were 9.3～39.4(%) and 36.7% respectively. The additive effects of J=16 locus at budding, boll opening, and growth period were greater than other loci groups, suggesting that this locus had a key role in the early-maturity of upland cotton. Compared to late-maturing parents, early- and mid- maturing parents had less genotype and phenotype values at budding, boll opening, and growth period, and more favorable earliness related loci. In the major loci groups for pre-frost lint, Xinluzao8×Jing8891 F1 pyramided all favorable loci among the crosses. Besides, heterozygous loci contributed more to pre-frost lint yield than homozygous loci in most crosses. The yield heterosis of hybrids was mainly determined by heterozygous loci, though homozygous loci also made a contribution. These results also suggested the necessity to use local elite earliness cotton cultivars as core parents and traits with both high additive effects and high heritability as selection criteria in a cotton breeding program.Both F2 and F2.3 populations were made from the two crosses of TM-1 with Xinluzao8, Xinluzao10, respectively. Two earliness upland cotton genetic maps were constructed by JoinMap V3.0 based on SSR marker data, with a total length of 1284.88 cM and 598.14 cM, and 127 and 54 polymorphic loci, respectively, covering 11.97% and 25.7% of the cotton genomes. The average distance between two loci was 10.12 cM and 10.68 cM respectively. The first map included eighteen chromosomes, with three linkage groups unassigned; while the second map included 12 chromosomes. QTL tagging was performed using composite interval mapping (CIM) method of Winqtlcart 2.5. Totally 61 significant QTL with LOD scores greater than threshold value were detected for 34 traits including maturity, yield and fiber quality in the two populations. QTL clusters were found on D7, including 4 yield QTL simultaneously detected in the two populations. The QTL on A2 and D7 controlling growth period and pre-frost lint yield respectively were concurrently identified in association analysis, showing great stability. An integrated map was constructed through bridge markers, with 154 polymorphic loci distributed on 18 chromosomes and 3 unassigned linkage groups. The length was 1519.31 cM, covering 30.38%of the genome, with average interval between two loci 9.86 cM. QTLs for maturity, yield, fiber quality and other agronomic traits were detected on A2, A5, A6, A6/D6, A7/D, D1, D2, D7 and D9 respectively. QTL clusters were concentrated on D7, A6 and A6/D6. Favorable alleles were mainly from the two earliness varieties Xinluzao8 and Xinluzao10, which had genetic background of 611 bo and King’s cotton respectively. Earliness as well as its related traits was controlled by different genes, and additive inheritance is the major genetic base.更多还原