Linkage map construction and mapping QTL for cotton fibre quality using SRAP, SSR and RAPD

Tetraploid cotton is one of the most extensively cultivated species. Two tetraploid species, Gossypium hirsutum L. and G. barbadense L., dominate the world's cotton production. To better understand the genetic basis of cotton fibre traits for the improvement of fibre quality, a genetic linkage map of tetraploid cotton was constructed using sequence‐related amplified polymorphisms (SRAPs), simple sequence repeats (SSRs) and random amplified polymorphic DNAs (RAPDs). A total of 238 SRAP primer combinations, 368 SSR primer pairs and 600 RAPD primers were used to screen polymorphisms between G. hirsutum cv. Handan208 and G. barbadense cv. Pima90 which revealed 749 polymorphic loci in total (205 SSRs, 107 RAPDs and 437 SRAPs). Sixty‐nine F₂ progeny from the interspecific cross of ‘Handan208’בPima90’ were genotyped with the 749 polymorphic markers. A total of 566 loci were assembled into 41 linkage groups with at least three loci in each group. Twenty‐eight linkage groups were assigned to corresponding chromosomes by SSR markers with known chromosome locations. The map covered 5141.8 cM with a mean interlocus space of 9.08 cM. A × test for significance of deviations from the expected ratio (1: 2: 1 or 3: 1) identified 135 loci (18.0%) with skewed segregation, most of which had an excess of maternal parental alleles. In total, 13 QTL associated with fibre traits were detected, among which two QTL were for fibre strength, four for fibre length and seven for micronaire value. These QTL were on nine linkage groups explaining 16.18‐28.92% of the trait variation. Six QTL were located in the A subgenome, six QTL in the D subgenome and one QTL in an unassigned linkage group. There were three QTL for micronaire value clustered on LG1, which would be very useful for improving this trait by molecular marker‐assisted selection.     

棉花子叶衰老过程中的生理生化变化

以棉花子叶为材料,对子叶衰老过程中的叶绿素、可溶性蛋白含量、干物重,三种保护酶(超氧化物歧化酶,过氧化物酶,过氧化氢酶)活性,以及丙二醛含量的变化进行研究。发现子叶在出土后19d开始衰老;叶绿素含量变化在很大程度上与SOD和CAT活性变化存在正相关,与MDA的含量变化负相关,但与POD活性变化不存在相关性。     

Improved RAPD amplification of recalcitrant plant DNA by the use of activated charcoal during DNA extraction

An efficient procedure has been developed for DNA extraction from cotton by modifying the original CTAB method. The major improvement concerns the use of activated charcoal to bind resinous and coloured compounds which copurify with the DNA. The efficiency of amplification by RAPD was used as a criterion to evaluate the action of activated charcoal. Twenty-five random decamers from Operon Technologies were used to compare DNA samples extracted in the presence or absence of activated charcoal. The results in terms of amplification suggest that the use of activated charcoal in DNA extraction enhances RAPD amplification. This technique was initially developed for cotton but it has been applied successfully to other recalcitrant plants such as coffee, rubber tree, cassava and banana.     

棉花（Gossypium hirsutum L.）花粉壁的发育

用光镜和透射电镜观察研究了棉花花粉壁的发育过程。棉花花粉壁的发生邕于四分孢子时期，四分体形成后，在小孢子的质膜与胼胝质壁之间逐渐形成多糖性质的原外壁。游离小孢子时期，在一定间隔的原外壁中小孢子质膜表面积累外壁物质并形成基粒棒，之后在基粒棒的下部和上部分别横向延展并接合形成基足层和覆盖层。花粉内壁发生     

Quantitation of cotton fibre-quality variations arising from boll and plant growth environments

Crop growth simulation models used to manage cultural inputs and to improve yields of cotton, Gossypium hirsutum L., do not address fibre quality, a major determinant of cotton fibre price and end-use. Fibre maturation simulations require rapid, reproducible methods for fibre quality quantitation at the boll or locule level. Combination of fibre quality mapping by fruiting site with quality quantitation by an electron-optical particle sizer provided replicated, reproducible data suitable for use in predictive models and quantitative studies of fibre quality variations attributable to genotype and growth environment. The efficacy and potential of this unique fusion of agronomic and textile technologies were examined through comparisons of three 1992 fibre quality database subsets from the US Southeastern Coastal Plain and Mississippi Delta. Comparisons of ‘Pee Dee 3’ fibre quality, on a locule-by-locule basis at positions 1 and 2 on main-stem nodes 5 through 18, revealed that fibre length, cross-sectional area, and physical maturity varied among fruiting sites. Subsurface microirrigation applied during an early-season drought increased fibre yield by 40%, significantly increased fibre fineness, and decreased fibre maturity indicators. Fibre length variations were compared between ginning methods and among nine genotypes grown in the Coastal Plain. Irrigation-related reductions in physical fibre maturity, found in the Coastal Plain, were contrasted with chronological maturities of ‘DPL5415’ and ‘DES119’ fibre harvested 21, 28, 35, 42, or 56 days post-anthesis in the Mississippi Delta. Fibre-quality mapping with particle-sizing represents a powerful, new tool for constructing fibre development simulations essential for improving cotton fibre quality and processing outcome.     

Value of various taxa in breeding tetraploid blueberries in Florida

Many species and races of blueberries native to the southeastern United States have been used in the University of Florida breeding program. Highbush blueberry cultivars from a program started in 1908 in the northern United States were used at the start of the Florida program as a source of early ripening, large fruit size and high fruit quality. Vaccinium species native to Florida were used to obtain adaptation to the Florida environment, which is characterized by a long growing season, mild winters interrupted by killing freezes, low number of chill hours, and warm, moist conditions that favor fungal pathogens. The Florida species that have proved most useful in breeding have been southern races of Vaccinium corymbosum, which produce hybrids with high vigor and upright growth habit, and V. darrowi, which produces hybrids that retain their leaves late into the winter and have a very low chilling requirement. Species that have been less useful in breeding are V. elliottii and V. myrsinites. V. arboreum, in Vaccinium section Batodendron, is the only species outside of section Cyanococcus that has been used in breeding Florida blueberries, and has been a good source of vigor and tolerance to soils low in organic matter and high in bicarbonates. Although the gene pool available for improving low-chill highbush blueberries is large and diverse, progress is slowed by the need to improve simultaneously a large number of traits. This revised version was published online in July 2006 with corrections to the Cover Date.     

盐胁迫对陆地棉愈伤组织的影响

利用组织培养技术、生化分析的方法，研究了不同盐压力（ＮａＣｌ）对陆地棉愈伤组织增长及蛋白质和氨基酸代谢的影响。结果表明：随着盐浓度不断提高，干重含量增大；蛋白质和氨基酸含量在０．５％～１．Ｏ％ＮａＣｌ浓度时出现峰值；而０．５％ＮａＣｌ浓度附近，愈伤组织停滞后转为迅速增长，其质地由灰色疏松状转变成白色致密状。较低ＮａＣｌ浓度对棉花愈伤组织生长有促进作用，而高ＮａＣｌ浓度对棉花愈伤组织有明显的抑制作用。     

施氮量对不同开花期棉（Gossypium hirsutum L.）铃纤维细度和成熟度形成的影响

为兼顾试验的重复性和生态区域性,选用高品质棉（科棉1号）和常规棉（美棉33B）品种为材料,于2005年分别在江苏南京（118o50E, 32o02N,长江流域下游棉区）和江苏徐州（11711E, 3415N,黄河流域黄淮棉区）设置施氮量（低氮:N 0 kg/hm2;适氮:N 240 kg/hm2;高氮:N 480 kg/hm2）试验,研究施氮量对不同开花期棉铃纤维细度、成熟度和马克隆值形成的影响。结果表明:（1）施氮量显著影响棉纤维细度、成熟度和马克隆值的形成过程,但三者在不同开花期对氮素水平的响应不同,施氮量与开花期对棉纤维细度、成熟度和马克隆值的形成存在互作效应。8月10日前开花的棉铃,铃期［花后0～50 d （DPA）］日均温在23.3 oC以上,纤维细度、马克隆值以N 0 kg/hm2施氮量下最大,棉纤维马克隆值与纤维细度的相关性较大;8月25日开花的棉铃（铃期日均温在20.8～23.3 oC之间）,纤维成熟度、马克隆值以N 240 kg/hm2施氮量下最大;9月10日开花棉铃（铃期日均温低于20.8 oC）,纤维细度、成熟度和马克隆值均以N 480 kg/hm2最大,棉纤维马克隆值与纤维成熟度的相关性增强。（2）影响不同开花期间纤维细度、成熟度和马克隆值的主要因素是铃期日均温,最终纤维细度、成熟度和马克隆值在不同施氮量之间的变异与不同开花期（铃期日均温不同）间的变异比较,前者显著小于后者。综上,因开花期不同而形成的铃期日均温是决定细度、成熟度和马克隆值的最重要因素,施氮量可通过对位叶叶氮浓度NA影响棉纤维细度、成熟度和马克隆值的形成过程,增加施氮量可减小上述指标在不同开花期间的差异。     

棉花产量稳定性的影响因素分析

按Eberhart和Russell(1966)的分析模式评价了八个陆地棉品种(系)皮棉产量等十个性状的稳定性。同时,采用Spearman等级相关的方法研究了皮棉产量稳定性与其他性状稳定性的相关关系。结果表明,分析的大多数品种(系)皮棉产量等十个性状的平均表现与环境指数呈显著或极显著的线性关系,皮棉产量的稳定性(平均产量对环境指数的回归系数)与单株成铃数和衣分的稳定性呈密切的正相关关系,与株高和果枝始节的稳定性亦呈显著的正相关。因此,进行稳产性育种可根据铃数、衣分、株高和果枝始节的稳定性进行间接选择。