Morphological, cytological and molecular analyses of a synthetic hexaploid derived from an interspecific hybrid between Gossypium hirsutum and Gossypium anomalum

Gossypium anomalum represents an inestimable source of genes that could potentially be transferred into the gene pool of cultivated cotton. To resolve interspecific hybrid sterility problems, we previously treated triploid hybrids derived from a cross between Gossypium hirsutum and G. anomalum with 0.15% colchicine and obtained a putative fertile hexaploid. In this study, we performed morphological, molecular and cytological analyses to assess the hybridity and doubled status of putative interspecific hybrid plants. Most of the morphological characteristics of the putative hexaploid plants were intermediate between G. hirsutum and G.anomalum. Analysis of mitotic metaphase plates revealed 78 chromosomes, confirming the doubled hybrid status of the hexaploid. Genome-wide molecular analysis with different genome-derived SSR markers revealed a high level of polymorphism(96.6%) between G. hirsutum and G. anomalum. The marker transferability rate from other species to G. anomalum was as high as 98.0%. The high percentage of polymorphic markers with additive banding profiles in the hexaploid indicates the hybridity of the hexaploid on a genome-wide level. A-genome-derived markers were more powerful for distinguishing the genomic differences between G. hirsutum and G. anomalum than D-genome-derived markers. This study demonstrates the hybridity and chromosomally doubled status of the(G. anomalum × G. hirsutum)2hexaploid using morphological, cytological and molecular marker methods. The informative SSR markers screened in the study will be useful marker resources for tracking the flow of G. anomalum genetic material among progenies that may be produced by future backcrosses to G. hirsutum.

Genome sequence of Gossypium anomalum facilitates interspecific introgression breeding

Crop wild relatives are an important reservoir of natural biodiversity. However, incorporating wild geneticdiversity into breeding programs is often hampered by reproductive barriers and a lack of accurate genomicinformation. We assembled a high-quality, accurately centromere-anchored genome of Gossypium anomalum, a stress-tolerant wild cotton species. We provided a strategy to discover and transfer agronomicallyvaluable genes from wild diploid species to tetraploid cotton cultivars. With a (Gossypium hirsutum 3 G.anomalum)2 hexaploid as a bridge parent, we developed a set of 74 diploid chromosome segment substitution lines (CSSLs) of the wild cotton species G. anomalum in the G. hirsutum background. This set of CSSLsincluded 70 homozygous substitutions and four heterozygous substitutions, and it collectively containedabout 72.22% of the G. anomalum genome. Twenty-four quantitative trait loci associated with plant height,yield, and fiber qualities were detected on 15 substitution segments. Integrating the reference genome withagronomic trait evaluation of the CSSLs enabled location and cloning of two G. anomalum genes thatencode peroxiredoxin and putative callose synthase 8, respectively, conferring drought tolerance andimproving fiber strength. We have demonstrated the power of a high-quality wild-species reference genomefor identifying agronomically valuable alleles to facilitate interspecific introgression breeding in crops.

异常棉NF-YA家族基因鉴定及其在干旱胁迫下的表达分析

NF-YA转录因子在植物生长发育和逆境响应中扮演重要角色。本研究通过生物信息学手段,分析棉花二倍体野生种异常棉基因组中NF-YA家族基因的数目、染色体分布、系统进化、保守基序、结构、顺式作用元件、表达模式及编码蛋白质的亚细胞定位、理化性质等。结果表明,异常棉NF-YA基因家族(GoanoNF-YA)包含17个成员,分布在10条染色体上,编码的蛋白质长度为190~603个氨基酸,理论等电点为7.87~10.07,16个成员包含3~5个外显子且编码的蛋白质定位于细胞核。拟南芥和异常棉NF-YA基因在系统进化树上分为6类,每类基因在系统进化树上具有相同或相似类型和排列顺序的基序。5个NF-YA基因在异常棉根、茎、叶和花中广泛表达,15个NF-YA基因对干旱持续时间有不同程度的响应,11个NF-YA基因含有干旱响应顺式作用元件MBS。本研究结果为进一步解析异常棉NF-YA家族基因的功能提供了理论依据。

国产酸浆属（茄科）的叶表皮和种皮特征及其分类学意义

在光学显微镜和扫描电镜下观察了茄科酸浆属５种２变种及邻近属２种植物：辣椒和龙珠的叶表皮及种皮特征，发现上述植物的叶上、下表皮细胞表面观形状为不规则形，垂周壁浅波状、波状或深波状；一些类群的气孔器在上、下表皮均存在，另一些类群的气孔器则仅在下表皮存在，其类型一致为无规则型。扫描电镜下叶下表皮的特征，包括角质膜以及气孔外拱盖和拱盖内缘的特征，有一定的分类学价值。此外，种皮纹饰可作为区分酸浆属。

陆地棉与异常棉远缘杂交后代的杂种优势利用

为了进一步研究棉花杂种优势的利用,采用G.hirsutum(陆地棉)与G.anomalum(异常棉)杂交培育出的稳定系DH966、DH967、DH968作母本,转基因抗虫棉SGK321和99B作父本分别进行成对杂交,杂种一代对产量及主要经济性状进行了测算及分析。结果表明:3个稳定系与SGK321、99B杂交一代6个杂交组合中有5个组合的子棉产量与皮棉产量的中亲优势超过40%,超标优势均在30%以上,单株结铃数的中亲优势超过20%,超标优势均在20%左右,铃重的中亲优势在15%左右,超标优势为10%左右,衣分、纤维上半部平均长度、断裂比强度的中亲优势均在2%左右,衣分的超标优势为3%左右,纤维上半部平均长度、断裂比强度的超标优势均在10%以上。马克隆值的中亲优势在-1%^-4%,超标优势在-2%^-6%。6个组合F_1的子棉产量、皮棉产量、单株结铃数和铃重均表现出有较强的超高亲优势,而衣分、绒长、断裂比强度、马克隆值均低于高亲值,优势均为负值。每个组合的全部统计性状F_1均表现出很强的超低亲优势。棉花远缘杂交稳定系与转基因抗虫棉用于杂种优势利用具有较大的潜力。

含异常棉基因棉纤维品质及超分子结构遗传效应

通过对３个含有异常棉血缘的陆地棉高强纤维种质系和４个推广品种的纤维品质和纤维超分子结构分析表明，纤维比强度越高，纤维微原纤角越小，取向度越高，而与成熟纤维的结晶度关系不密切。４×３的不完全双列杂交分析表明，纤维品质和纤维超分子结构参数的基因型方差（除结晶度外）都达显著或极显著水平，对基因型方差进一步分解表明，母本的纤维比强度、长度、取向度和微原纤角的一般配合力均方达显著或极显著水平，其中泗棉３号的一般配合力最高。仅纤维比强度的特殊配合力均方达显著水平。纤维比强度以泗棉３号×７２３５为最高。Ｆ１与双亲均值的相关分析结果表明难以根据组合的中亲值来预测其杂交组合Ｆ１的表现。