棉花耐盐相关种质资源遗传多样性分析

为了解我国棉花耐盐相关种质资源的遗传变异,利用88对SSR引物对23份棉花耐盐材料和24份盐敏感材料进行遗传多样性分析。88个SSR位点在47份材料中共检测出338个等位基因变异,平均每个位点有3.841个;其中耐盐材料中检测出333个,盐敏感材料中检测出312个。耐盐材料的位点多态信息含量(PIC)、每个位点的有效等位基因数(Ne)、基因型多样性(H′)分别为0.613、2.929和1.083,盐敏感材料的PIC、Ne、H′分别为0.605、2.883和1.071。耐盐材料和盐敏感材料的Jaccard相似性系数分别在0.530–0.979和0.525–0.878之间,遗传相似性系数总体平均值接近,但耐盐材料的变化幅度更大。用类平均法(UPGMA)聚类将47份材料分成3个类群。总体而言,大多数材料之间的遗传相似性系数较高,表明我国陆地棉耐盐相关种质资源遗传基础狭窄。本结果为棉花耐盐育种中亲本的选配和优势组合的预测以及耐盐资源的合理利用等提供了基础资料。     

Genetic analysis of seed coat development in Arabidopsis

In the angiosperms, fertilization initiates the formation of the seed from the ovule, including the differentiation of the seed coat from the ovule integuments. Seed coat differentiation includes some of the most dramatic cellular changes of seed development and culminates in the death of the seed coat cells. Recently, genetic analyses in Arabidopsis have contributed substantially to our understanding of many aspects of seed coat biology and it might not be long before the entire differentiation pathway is understood. Such an advance would contribute substantially to our understanding of many important cellular events, including secondary cell wall synthesis, cell morphogenesis, vacuolar targeting and cell death, and would provide tools for the manipulation of seed dormancy and germination.     

Genetic mapping of new cotton fiber loci using EST-derived microsatellites in an interspecific recombinant inbred line cotton population

There is an immediate need for a high-density genetic map of cotton anchored with fiber genes to facilitate marker-assisted selection (MAS) for improved fiber traits. With this goal in mind, genetic mapping with a new set of microsatellite markers [comprising both simple (SSR) and complex (CSR) sequence repeat markers] was performed on 183 recombinant inbred lines (RILs) developed from the progeny of the interspecific cross Gossypium hirsutum L. cv. TM1 × Gossypium barbadense L. Pima 3-79. Microsatellite markers were developed using 1557 ESTs-containing SSRs (≥10 bp) and 5794 EST-containing CSRs (≥12 bp) obtained from ~14,000 consensus sequences derived from fiber ESTs generated from the cultivated diploid species Gossypium arboreum L. cv AKA8401. From a total of 1232 EST-derived SSR (MUSS) and CSR (MUCS) primer-pairs, 1019 (83%) successfully amplified PCR products from a survey panel of six Gossypium species; 202 (19.8%) were polymorphic between the G. hirsutum L. and G. barbadense L. parents of the interspecific mapping population. Among these polymorphic markers, only 86 (42.6%) showed significant sequence homology to annotated genes with known function. The chromosomal locations of 36 microsatellites were associated with 14 chromosomes and/or 13 chromosome arms of the cotton genome by hypoaneuploid deficiency analysis, enabling us to assign genetic linkage groups (LG) to specific chromosomes. The resulting genetic map consists of 193 loci, including 121 new fiber loci not previously mapped. These fiber loci were mapped to 19 chromosomes and 11 LG spanning 1277 cM, providing approximately 27% genome coverage. Preliminary quantitative trait loci analysis suggested that chromosomes 2, 3, 15, and 18 may harbor genes for traits related to fiber quality. These new PCR-based microsatellite markers derived from cotton fiber ESTs will facilitate the development of a high-resolution integrated genetic map of cotton for structural and functional study of fiber genes and MAS of genes that enhance fiber quality. Electronic Supplementary Material Supplementary material is available for this article at Names are necessary to report factually on available data, however, the USDA neither guarantees nor warrants the standard of products or service, and the use of the name by the USDA implies no approval of the products or service to the exclusion of others that may also be suitable.     

Molecular evolution and phylogenetic analysis of genes related to cotton fibers development from wild and domesticated cotton species in Gossypium

The domestication of both diploid and tetraploid cotton species was carried out for fiber utilization. To understand the origin and domestication of fibers, 18 genes related to fiber development were individually cloned and sequenced from 22 different cotton species. Their structures, phylogenetic relationship and molecular evolution were further studied. In the orthologous and homeologous loci of the 18 genes, the sequence and structure of 72.22% were conserved and 27.78% were diverse. Tree topologies constructed based on the combined sequences showed that all 13 D-genome species were congruent with Fryxell's subsection taxonomy, the A- and D-subgenomes independently evolved in the allopolyploid after polyploid formation, and Gossypium raimondii had the closest relationship with all allotetraploids of D-subgenomes. The molecular evolutionary rates revealed approximately equivalent rates among different D-genome species, and purifying selection acted on all genes in the wild D-genome species. Among orthologs and homeologs, the D-subgenomes had higher evolutionary rates than the A-subgenomes in tetraploid cotton species, and the cultivars had higher evolutionary rates than either the semi-domesticated or wild species. Our study revealed that human domestication altered the molecular evolutionary pattern of genes related to fiber development, and Gossypium hirsutum endured greater selective pressures than Gossypium barbadense during the domestication process.     

Genetic differences in seed longevity of various Arabidopsis mutants

Seeds gradually lose their viability during dry storage. The damage that occurs at the biochemical level can alter the seed physiological status and is affected by the storage conditions of the seeds. Although these environmental conditions controlling loss of viability have been investigated frequently, little information is available on the genetics of seed longevity. Using Arabidopsis mutants in defined developmental or biochemical pathways such as those affected in seed coat composition, seed dormancy, hormone function and control of oxidative stress, we tried to gain insight into the genes and mechanisms controlling viability of stored seeds. Mutations like abscisic acid insensitive3 ( abi3 ) as well as abscisic acid deficient1 ( aba1 ) show reduced longevity, which may be partially related to the seed dormancy phenotype of these mutants. Mutants with seed coat alterations, especially aberrant tests shape ( ats ), showed a stronger reduction in germination percentage after storage, indicating the importance of a 'functional' seed coat for seed longevity. A specific emphasis was placed on mutants affected in dealing with Reactive Oxygen Species (ROS). Because several pathways are involved in protection against ROS and because gene redundancy is a common feature in Arabidopsis , 'double' mutants were generated. These 'double' mutants and the corresponding single mutants were subjected to a controlled deterioration test (CDT) and a germination assay on hydrogen peroxide (H₂O₂) after prolonged storage at two relative humidities. CDT and germination on H₂O₂ affected all genotypes, although it appears that other effects like genetic background are more important than the deficiencies in the ROS scavenging pathway. Explanations for this limited effect of mutations affecting ROS scavenging are discussed.     

影响棉纤维分化和发育的因素

影响棉纤维生长发育的主要因素是：基因型、激素、温度、水分、光照、授粉受精状况等。基因型决定棉纤维分化发育方式，内源或外源激素调控纤维分化、伸长、次生壁形成等发育过程。温度对纤维分化发育也有很大程度的影响。离体纤维生长发育除了受上述因素影响外，还受微量元素、维生素、ＮＨ４＾＋、ＣＯ２浓度等影响。     

Genetic mapping of resistance to purple seed stain in PI 80837 soybean

Purple seed stain (PSS) of soybean caused by Cercospora kikuchii is an important disease that reduces market grade and can affect seed germination and vigor. A single dominant gene was shown to confer PSS resistance in PI 80837. The objective of this research was to map the PSS resistance gene in PI 80837 using simple sequence repeat (SSR) markers. A cross was made between the PSS-susceptible cultivar Agripro 350 (AP 350) and PI 80837. The F2 population and parents were grown in the field, and the resistance or susceptibility of individual plants was determined by assaying the seed for infection by C. kikuchii. DNA of parent and F2 plants was extracted for SSR analysis and mapping. Segregation ratios for seed infection and for SSR markers showed that a single dominant gene conditions resistance to PSS in PI 80837. The candidate resistance gene was mapped between Sat_308 (6.6 cM) and Satt594 (11.6 cM) on molecular linkage group G. These markers may be useful in marker-assisted selection for utilizing PSS resistance from PI 80837 in a breeding program.     

Genetic mapping and quantitative trait locus analysis of fiber quality traits using a three-parent composite population in upland cotton (Gossypium hirsutum L.)

Composite cross populations (CP) developed from three or more cultivars/lines are frequently used to improve agronomic and economic traits in crop cultivar development programs. Employing CP in linkage map construction and quantitative trait locus (QTL) mapping may increase the marker density of upland cotton (Gossypium hirsutum L.) genetic maps, exploit more adequate gene resources and facilitate marker-assisted selection (MAS). To construct a relatively high-density map and identify QTL associated with fiber quality traits in upland cotton, three elite upland cultivars/lines, Yumian 1, CRI 35 and 7,235, were used to obtain the segregating population, Yumian 1/CRI 35//Yumian 1/7,235. A genetic map containing 978 simple sequence repeat (SSR) loci and 69 linkage groups was constructed; the map spanned 4,184.4 cM, covering approximately 94.1% of the entire tetraploid cotton genome. A total of 63 QTL were detected, explaining 8.1–55.8% of the total phenotypic variance: 11 QTL for fiber elongation, 16 QTL for fiber length, 9 QTL for fiber micronaire reading, 10 QTL for fiber strength and 17 QTL for fiber length uniformity. The genetic map and QTL detected for fiber quality traits are promising for further breeding programs of upland cotton with improved fiber quality.     

Comparative development of fiber in wild and cultivated cotton

SUMMARY One of the most striking examples of plant hairs is the single-celled epidermal seed trichome of cultivated cotton. The developmental morphology of these commercial "fibers" has been well-characterized in Gossypium hirsutum , but little is known about the pattern and tempo of fiber development in wild Gossypium species, all of which have short, agronomically inferior fiber. To identify developmental differences that account for variation in fiber length, and to place these differences in a phylogenetic context, we conducted SEM studies of ovules at and near the time of flowering, and generated growth curves for cultivated and wild diploid and tetraploid species. Trichome initiation was found to be similar in all taxa, with few notable differences in trichome density or early growth. Developmental profiles of the fibers of most wild species are similar, with fiber elongation terminating at about two weeks post-anthesis. In contrast, growth is extended to three weeks in the A- and F-genome diploids. This prolonged elongation period is diagnosed as a key evolutionary event in the origin of long fiber. A second evolutionary innovation is that absolute growth rate is higher in species with long fibers. Domestication of species is associated with a further prolongation of elongation at both the diploid and allopolyploid levels, suggesting the effects of parallel artificial selection. Comparative analysis of fiber growth curves lends developmental support to previous quantitative genetic suggestions that genes for fiber "improvement" in tetraploid cotton were contributed by the agronomically inferior D-genome diploid parent.     

Genetic mapping and analysis of quantitative trait loci affecting fiber and lignin content in maize

Plant cell walls of forage provide a major source of energy for ruminant animals. Digestion of cell walls is limited by the presence of lignin, therefore the improving the digestibility of forages by reducing lignin content is a major goal in forage crop breeding programs. A recombinant inbred line maize population was used to map quantitative trait loci (QTL) for neutral detergent fiber (NDF), acid detergent fiber (ADF), and acid detergent lignin (ADL) of leaf-sheath and stalk tissues. All traits were positively genetically correlated. The larger genetic correlations were between NDF and ADF in sheaths (r = 0.84), NDF and ADF (r = 0.96), ADF and ADL (r = 0.83), and NDF and ADL (r = 0.76) in stalks. Twelve QTL were detected for NDF and 11 QTL for ADF in leaf-sheaths. Eight QTL detected for both traits were defined by the same or linked marker loci. Eight QTL were associated with leaf-sheath ADL. Eleven QTL were detected for NDF and ADF, and 12 QTL for ADL in stalks. Nine of eleven QTL detected for both NDF and ADF in stalks coincided in their genomic position. A high proportion of QTL detected for these traits had the same parental effects and genomic locations, suggesting that it is only necessary to select on one fiber component (NDF or ADF) to improve digestibility. Favorable correlated responses of unselected fiber components are expected due to coincident genomic locations of QTL and the high genetic correlation between fiber components. Several QTL detected in this study coincided in their positions with putative cellulose synthase genes from maize.     

Role of abscisic acid in cotton fiber development

Fibers of three cotton cultivars varying widely in their final fiber length, i.e., long staple (Gossypium hirsutum H-4), middle staple (G. Hirsutum H-8), and short staple (G. Arboretum G. Cot-15) were analyzed to study the role of ABA in fiber elongation and dry matter accumulation, in vivo and in vitro. The fibers were analyzed for different growth parameters and endogenous ABA content during the entire period of their development using indirect ELISA by raising the antibodies against ABA. From growth analysis, cotton fiber development was divided into four distinct phases, (i) initiation, (ii) elongation, (iii) secondary thickening, and (iv) maturation. An inverse correlation between final fiber length and ABA content was observed in all the cultivars. In long staple cultivar (H-4), rapid ABA accumulation started after fiber had attained peak elongation growth while, in short staple cultivar (G. Cot-15), ABA accumulation was observed even during elongation growth. Significant inhibition in length of short and middle staple cultivars as compared to long staple cultivar was observed in in vitro grown fibers when media were supplemented with ABA (1, 3, and 5 mg/l). The addition of growth promoters like NAA and GA, along with ABA, has reduced the inhibition in fiber elongation in all the cultivars. These results suggest a regulatory role of ABA in cotton fiber elongation along with auxins and gibberellins. Published in Russian in Fiziologiya Rastenii, 2006, Vol. 53, No. 1, pp. 68–74. The text was submitted by the authors in English.     

Suppression of sucrose synthase gene expression represses cotton fiber cell initiation,elongation, and seed development

Cotton is the most important textile crop as a result of its long cellulose-enriched mature fibers. These single-celled hairs initiate at anthesis from the ovule epidermis. To date, genes proven to be critical for fiber development have not been identified. Here, we examined the role of the sucrose synthase gene (Sus) in cotton fiber and seed by transforming cotton with Sus suppression constructs. We focused our analysis on 0 to 3 days after anthesis (DAA) for early fiber development and 25 DAA, when the fiber and seed are maximal in size. Suppression of Sus activity by 70% or more in the ovule epidermis led to a fiberless phenotype. The fiber initials in those ovules were fewer and shrunken or collapsed. The level of Sus suppression correlated strongly with the degree of inhibition of fiber initiation and elongation, probably as a result of the reduction of hexoses. By 25 DAA, a portion of the seeds in the fruit showed Sus suppression only in the seed coat fibers and transfer cells but not in the endosperm and embryo. These transgenic seeds were identical to wild-type seeds except for much reduced fiber growth. However, the remaining seeds in the fruit showed Sus suppression both in the seed coat and in the endosperm and embryo. These seeds were shrunken with loss of the transfer cells and were <5% of wild-type seed weight. These results demonstrate that Sus plays a rate-limiting role in the initiation and elongation of the single-celled fibers. These analyses also show that suppression of Sus only in the maternal seed tissue represses fiber development without affecting embryo development and seed size. Additional suppression in the endosperm and embryo inhibits their own development, which blocks the formation of adjacent seed coat transfer cells and arrests seed development entirely.     

Genetic analysis of some seed quality characters in upland cotton (Gossypium hirsutum L.)

Summary A set of diallel crosses involving ten parents was evaluated over two locations to determine the genetic control of protein per cent, oil per cent, seed index, percentage of mature seeds and number of seeds per boll. The analysis of pooled data showed that percentage of mature seeds was controlled by additive (D) and non-additive (H₁ and H₂) genetic effects. Overdominance was noticed. For seed index the D component measuring additive, and the H₂ component measuring dominance, variation were significant. Protein content and oil content were primarily under the control of non-additive (H₁ and H₂) genetic effects, while for number of seeds per boll the variability was accounted for by dominance (H₁) effects only. The development of pure lines through appropriate methods is suggested.Part of the thesis of the senior author, submitted in partial fulfilment for the Ph.D. degree     

The role of phytohormones in cotton fiber development

Since 1974, when Beasley and Ting discovered that fertilized ovules of cotton can be cultured in media supplemented with GA along with auxin, the effect of all types of phytohormones on fiber development has been widely studied. Many phytohormones, including GA, IAA, brassinosteroid (Br), ABA, ethylene (Et), and cytokinins (Ck), all have been demonstrated to play important roles during cotton fiber development. In recent years, the rapid development of genomic analysis and the accumulation of high-quality cotton ESTs allowed us to probe phytohormonal gene expression during fiber development. Many phytohormonal genes, including GA-, IAA-, ABA-, Br-, Et-, and Ck-related genes, participating in phytohormone biosynthesis pathways and signal transduction pathway accumulated in the process of cotton fiber development.     

The accumulation of pigment in fiber related to proanthocyanidins synthesis for brown cotton

Brown cotton is a kind of naturally colored cotton. Because of less processing and little dying, it is more friendlier to environment than white cotton. For brown cotton, pigment accumulation in fiber is one of the most important characteristics. In this study, we selected a brown fiber line and a white fiber cultivar to determine the factor that affects the pigmentation in brown fiber. Accordingly, fibers were collected to verify the presence of PAs by p-dimethylaminocinnamaldehyde (DMACA) and toluidine blue O (TBO) staining. The PAs content and related genes expressions were determined. As a result, there were obvious differences on the aspect of PAs synthesis in fiber between white cotton and brown cotton. For white fiber, the PAs content reached maximum at 5 DPA, and then gradually decreased to zero. But for brown fiber, the PAs content was increased from 5 to 15 DPA stage, and reached the maximum at the 15 DPA stage, then gradually decreased from 15 to 40 DPA stage. On the contrary, in white cotton, PAs were synthesized in the whole developmental stage from 5 to 40 DPA. And PAs content in brown fiber were far more than that in white fiber, which may be the reason why the brown pigment accumulated in brown fiber.     

Nucleolar size at early stages of cotton fiber development in relation to final fiber dimension

Changes in nucleolar size and nucleolar vacuolation at early stages of fiber development and final fiber dimensions were determined for cotton of different species: Gossypium hirsutum L. cv. B49, Gossypium barbadense L. cv. Menoufi and Gossypium arboreum L. cv. Virnar. Size of the nucleolus in combination with its vacuolation at an early stage of development was found to be clearly associated with the final result of fiber development.     

The seven deadly sins of comparative analysis

Phylogenetic comparative methods are extremely commonly used in evolutionary biology. In this paper, I highlight some of the problems that are frequently encountered in comparative analyses and review how they can be fixed. In broad terms, the problems boil down to a lack of appreciation of the underlying assumptions of comparative methods, as well as problems with implementing methods in a manner akin to more familiar statistical approaches. I highlight that the advent of more flexible computing environments should improve matters and allow researchers greater scope to explore methods and data.     

An analysis of seed development in Pisum sativum XVIII. The isolation of mutants defective in embryo development

Following EMS mutagenesis of pea (Pisum sativum L.) seed, ninemutants have been isolated whose embryos are affected in theirdevelopment, being defective either in organogenesis or in celldifferentiation. Studies of their morphology at the whole organlevel and their histology indicated at least four groups: thosewith single cotyledons (representing at least three loci), twoblocked at the early cotyledonary stage, one with abnormal rootdevelopment and two with cellular defects. Genetic analysisindicated the mutants were behaving as monogenic recessive mutations.These mutants represent the first of their type for legumesand should prove especially useful, therefore, for examiningthose aspects of development characteristic of these species. Key words: Cellular development, cotyledon, embryogenesis, morphogenesis, mutagenesis     

赤霉素信号转导与棉纤维的分子发育

赤霉素(Gas)作为一种高效能的植物生长调节物质对棉纤维的分化和发育有着非常重要的影响, 但是, 一直以来有关赤霉素与棉纤维分化和发育的分子机制的研究还很少。文章论述了近年来GA信号组分、转导途径的分子生物学研究进展以及GA与棉纤维分子发育的相关研究成果, 旨在为揭示赤霉素调控棉纤维分化和发育的分子机制以及改善棉纤维品质的棉花育种工作提供新的思路。     

Unbiased genomic distribution of genes related to cell morphogenesis in cotton by chromosome mapping

Cell dedifferentiation, somatic embryogenesis, and cell wall regeneration are key steps in plant regeneration. In order to improve the efficiency of plant regeneration in cotton, we mapped genes related to cell morphogenesis. A total of 489 markers, including SSRs, PIPs, and sequence-specific markers related to cell dedifferentiation, somatic embryogenesis, and cell wall regeneration were developed. Only 19 markers showed polymorphism between parents of the mapping population upon high-resolution gel and SSCP analysis, and 21 polymorphic loci were generated. Thirteen loci were mapped on 9 cotton chromosomes, four of which were on Chr16. Seven of the 13 loci were mapped on the At sub-genome and six on the Dt sub-genome. This study provides an overview of the chromosome distribution of genes related to cell morphogenesis in cotton. The markers developed in this study will be useful in marker-assisted selection of better genotypes for plant regeneration in cotton.