Genetic effects of nine <Emphasis Type="Italic">Gossypium barbadense</Emphasis> L. chromosome substitution lines in top crosses with five elite Upland cotton <Emphasis Type="Italic">G. hirsutum</Emphasis> L. cultivars

Crosses between Gossypium barbadense L and Gossypium hirsutum L. (Upland cotton) have produced limited success in introgressing fiber quality genes into the latter. Chromosome substitution lines (CSBL) have complete chromosomes or chromosome arms from G. barbadense, line 3-79, substituted for the corresponding chromosome or arms in G. hirsutum in a near isogenic background of TM-1. We top crossed nine CSBL and their parents (TM-1 and 3-79) with five cultivars. Parental lines and their F₂ populations were evaluated in four environments for agronomic and fiber quality traits. The CSBL and their F₂ hybrids showed wide ranges for both agronomic and fiber traits of economic importance. Genetic analysis showed that additive variances were larger than dominance variances for lint percentage, boll weight, lint yield, fiber length, strength, elongation, micronaire, and yellowness; whereas, dominance variances were larger than additive variances only for uniformity of fiber length and equal for fiber reflectance. For all traits, except boll weight and lint yield, significant additive effects of one or more chromosomes from 3-79 in TM-1 background were greater than the corresponding TM-1 chromosome. In addition, we identified specific chromosomes from G. barbadense (3-79) that carry alleles for improvements in specific fiber quality traits in Upland cotton. Favorable additive effects of individual chromosomes or chromosome segments from 3-79 relative to corresponding chromosomes or chromosomes segments from TM-1 were identified in this study as follows: Lint percentage, chromosome/arms 10, 16-15; longer fibers, chromosome/arms 01, 11sh, 26Lo; more uniform fibers, chromosomes/arms 01, 11sh, 10, 17-11; stronger fibers, chromosome/arms 01, 11sh, 12sh, 26Lo, 17-11; fiber elongation, chromosomes/arms 01, 11sh, 26Lo, 10, 17-11; reduced fiber micronaire, chromosome/arms 01, 12sh, 4-15, 16-15, 17-11; fibers with more reflectance, chromosome/arms 10, 4-15, 16-15, 17-11; fiber with less yellowness, chromosome arms 4-15, 17-11. Based on the present study, we concluded that by using CSBL, favorable fiber quality alleles can be introgressed into Upland cotton, thus greatly improving the breeder’s ability for improvement of Upland cotton for a variety of traits. These data should provide useful genetic information to the cotton breeding industry at large.     

BAC-derived SSR markers chromosome locations in cotton

Bacterial artificial chromosome (BAC) libraries with large DNA fragment inserts have rapidly become the preferred choice for physical mapping. BAC-derived microsatellite or simple sequence repeats (SSRs) markers facilitate the integration of physical maps with genetic maps. The objective of this research was to identify chromosome locations of the BAC-derived SSR markers in tetraploid cotton. A total of 192 SSR primer pairs were derived from BAC clones of an Upland cotton genetic standard line TM-1 (Gossypium hirsutum L.). Metaphor agarose gel electrophoresis results revealed 76 and 59 polymorphic markers between TM-1 and 3–79 (G. barbadense) or G. tomentosum, respectively. Using deletion analysis method, we assigned 39 markers out of the 192 primer pairs to 17 different chromosomes or chromosome arms. Among them, 19 and 17 markers were localized to A-subgenomes (chromosome 1–13) and D-subgenomes (chromosome 14–26), respectively. The subgenome status for the remaining three markers remained unclear due to their two potential chromosome locations achieved by tertiary monosomic stocks deletion analysis. Chromosomal assignment of these BAC-derived SSR markers will help in integrating physical and cotton genetic linkage maps and thus facilitate positional candidate gene cloning, comparative genome analysis, and the coordination of chromosome-based genome sequencing project in cotton. Disclaimer: Mention of trademark, proprietary product, or vendor does not constitute a guarantee or warranty of the product by USDA, ARS and does not imply its approval to the exclusion of other products or vendors that may also be suitable. The U.S. Government’s right to retain a non-exclusive, royalty-free license in and to any copyright is acknowledged.     

Genotypic comparisons of chromosomes 01, 04, and 18 from three tetraploid species of <Emphasis Type="Italic">Gossypium</Emphasis> in topcrosses with five elite cultivars of <Emphasis Type="Italic">G. hirsutum</Emphasis> L.

Upland cotton, Gossypium hirsutum L. is the most widely planted cultivated cotton in the United States and the world. The other cultivated tetraploid species G. barbadense L. is planted on considerable less area; however, it produces extra long, strong, and fine fibers which spins into superior yarn. The wild cotton tetraploid species G. tomentosum Nuttall ex Seemann, native to the Hawaiian Archipelago also exhibits traits, such as drought tolerance, that would also be desirable to transfer to Upland cotton. Long-term breeding efforts using whole genome crosses between Upland and these species have not been successful in transferring very many desirable alleles into Upland cotton. Our chromosome substitution lines (CSL) have one chromosome or chromosome arm from an alien species backcrossed into the Upland cotton line,TM-1, via aneuploid technology. Five Upland cultivars were crossed with CS-B01, CS-T01, CS-B04, CS-T04, CS-B18 and CS-T18 and TM-1 the recurrent parent of the CSLs. This provided an opportunity to determine the effects of chromosomes 01, 04, and 18 from the three species in crosses with the five cultivars. Predicted genotypic mean effects of the parents, F₂, and F₃ generations for eight agronomic and fiber traits of importance were compared. The predicted hybrid mean effects for the three chromosomes from each species were different for several of the traits across cultivars. There was no single chromosome or species that was superior for all traits in crosses. Parental and hybrid lines often differed in the effect of a particular chromosome among the three species. The predicted genotypic mean effects for F₂ and F₃, with a few exceptions, generally agree with our previous results for additive and dominance genetic effects of these CSL.     

Seed trait evaluation of <Emphasis Type="Italic">Gossypium barbadense</Emphasis> L. chromosomes/arms in a <Emphasis Type="Italic">G. hirsutum</Emphasis> L. background

Investigation of cotton nutritional components is important because its seeds provide a useful nutritional profile and can possibly serve as a biofuel resource. In this study, five cultivars, 13 cotton chromosome substitution (CS-B) lines, their donor parent, '3-79', and their recurrent parent, 'TM-1', were evaluated for seed traits over four environments. A mixed linear model approach with the jackknife method was employed to estimate variance components and to predict genotypic effects for each seed trait. Genotypic effects were more important than genotype by environment interaction for all seed traits. Chromosome associations with these seed traits were detected using the comparative method by comparing the differences between each CS-B line and TM-1. For example, chromosome 4 of 3-79 in TM-1 background was associated with reduced seed index (SI), embryo percentage, protein percentage while associated with increased seed oil percentage and seed fiber percentage. Other chromosome associations with these seed traits were also observed in this study. SI was highly correlated with three seed index traits: seed protein index, seed oil index (OI), and seed fiber index. Lint percentage, boll number, and lint yield were positively correlated with protein percentage while negatively correlated with SI and OI. SI and seed fiber content exhibited negative correlations with micronaire but positive correlations with fiber length and strength. Results suggested that agronomic traits and seed nutrition components can be improved simultaneously.     

肾形线虫的筛选方法及其在陆地棉和海岛棉鉴定中的应用

两个陆地棉品种 SJ-125 和岱字棉 5415以及海岛棉 T-1348 用来筛选和建立温室条件下鉴定肾形线虫(Rotylenchulus reniformis)的有效方法,并对 12 个陆地棉品种(系)进行了鉴定.鉴定材料的株高、地上干重和根干重差异显著,真叶数和第一果枝节位差异不显著,接种7周后根干重与肾形线虫繁殖系数间呈负相关.繁殖系数随接种量增加而下降.适当的鉴定指标是每毫升土壤接种量7.4个,温室中接种7周后鉴定.利用本研究中改进的方法鉴定出2个耐肾形线虫品系.     

Fine mapping of open-bud duplicate genes in homoelogous chromosomes of tetraploid cotton

The open-bud mutant plant has a flower bud that is open at its tip due to the shortening of the corollas, resulting in exposure of the stigma and upper anthers. This mutant plant is potentially useful as a parent for producing hybrid cotton seeds. We have identified the open-bud trait to be inherited as recessive duplicate genes and finely mapped them in the homoelogous chromosome (chr) pair of chr. 18 (D13) and 13 (A13). Gossypium hirsutum substitution line 18, which has chr. 18 replaced by its corresponding homozygous chromosome in G. barbadense acc. 3-79 and the genotyped open-bud duplicate genes ob ₁ ob ₁ ob ₂ ob ₂, was crossed with the monomeric genotypic G. hirsutum acc. TM-1 and G. barbadense acc. 3-79 to produce two mapping populations. We then fine-mapped the duplicate open-bud gene ob ₁ in the chr. 18 (D13) and ob ₂ in the chr. 13 (A13) homoelogous chromosome pair in tetraploid cotton. Molecular markers closely linked with ob ₁ and ob ₂ will be useful tools in the development of open-bud lines by marker-assisted selection.     

Genetic analysis and quantitative trait locus mapping of PEG‐induced osmotic stress tolerance in cotton

Water stress is one of the major abiotic stresses that adversely affect cotton production. Seedlings of 142 backcross inbred lines (BILs) derived from Pima cotton ‘Pima S‐7’ (Gossypium barbadense L.) × Upland cotton ‘Sure‐Grow 747’(G. hirsutum L.) were evaluated in two tests for plant height, fresh shoot weight and root weight under two treatments (5% PEG and water‐control conditions) using a hydroponic system in the greenhouse. The experiment in each test was a randomized complete block design with three replicates. The analysis of variance for the two tests detected significant genotypic variation in PEG‐induced stress tolerance within the BIL population and between the parents. Heritabilities were moderate to high and were higher under the control conditions than under the PEG treatment, and the three traits were also significantly and positively correlated. Based on a linkage map with 292 loci, six QTLs were detected including two for plant height, and two each for fresh shoot weight and root weight. This study represents the first report in using a permanent mapping population in genetic and linkage analysis of water stress tolerance in cotton.     

利用置换系检测棉花第22染色体短臂的产量相关性状QTLs

CSB22sh为以陆地棉(Gossypium.hirsutum L.)遗传标准系TM-1为背景的第22染色体短臂被海岛棉(Gossypium.barbadense L.)Pima3-79置换的海陆置换系。TM-1与CSB22sh杂交,构建了104个F2单株的作图群体,应用6748对SSR引物对亲本进行分子标记筛选,获得90个多态性标记位点。其中85个标记位点构建了总长85.24 cM的遗传图谱,标记间平均距离1.0 cM,覆盖棉花基因组的1.8%。通过复合区间作图法对F2:3和F2:4家系的7个产量相关性状(衣分、铃重、子指、株高、第一果枝节位、单株铃数、单株果枝数)进行QTL检测,共检出28个不同QTLs,解释性状表型变异的3.5%～44.8%。仅在一个环境中检测到的QTLs有17个,2个环境同时检测到的QTLs有8个,3个环境同时检测到的QTLs有3个。不同的QTL在相同区段的成簇分布表明,控制不同性状的基因可能紧密连锁或一因多效。检测到的稳定的QTL可以用于相应性状的分子标记辅助选择。     

A microsatellite-based genome-wide analysis of genetic diversity and linkage disequilibrium in Upland cotton (Gossypium hirsutum L.) cultivars from major cotton-growing countries

To better understand the genetic diversity of the cultivated Upland cotton (Gossypium hirsutum L.) and its structure at the molecular level, 193 Upland cotton cultivars collected from 26 countries were genotyped using 448 microsatellite markers. These markers were selected based on their mapping positions in the high density G. hirsutum TM-1 × G. barbadense 3-79 map, and they covered the whole genome. In addition, the physical locations of these markers were also partially identified based on the reference sequence of the diploid G. raimondii (D₅) genome. The marker orders in the genetic map were largely in agreement with their orders in the physical map. These markers revealed 1,590 alleles belonging to 732 loci. Analysis of unique marker allele numbers indicated that the modern US Upland cotton had been losing its genetic diversity during the past century. Linkage disequilibrium (LD) between marker pairs was clearly un-even among chromosomes, and among regions within a chromosome. The average size of a LD block was 6.75 cM at r ² = 0.10. A neighbor-joining phylogenic tree of these cultivars was generated using marker allele frequencies based on Nei’s genetic distance. The cultivars were grouped into 15 groups according to the phylogenic tree. Grouping results were largely congruent with the breeding history and pedigrees of the cultivars with a few exceptions.     

Alien chromosome transmission and somatic elimination in monosomic addition lines of Gossypium australe F. Muell in G. hirsutum L.

The efficiency of using monosomic alien addition lines (MAALs) to introgress agronomical traits of interest carried by wild diploid Gossypium species into the main cultivated cotton species G. hirsutum depends on the opportunities of confronting the alien chromosome with the recipient background genome at each generation and on the occurrence of translocations and homoeologous recombinations. The selfed-progeny of five MAALs of G. australe in G. hirsutum was screened with SSR markers to determine the transmission frequency of the alien chromosome and monitor its integrity. Three MAALs revealed a transmission frequency significantly lower than the expected ratio and one MAAL presented an exclusive transmission of the additional chromosome. In these four MAAL the alien chromosome was transmitted almost unaltered. With the fifth MAAL the alien chromosome was normally transmitted but was altered in half of the plants carrying it. In one MAAL, normally carrying brown fiber, the emergence of some plants carrying white and brown fiber revealed the somatic elimination of the additional chromosome. The loss of this chromosome seems to be triggered by its deletion.     

Molecular mapping and characterization of traits controlling fiber quality in cotton

Cotton (Gossypium spp) is the world's leading natural fiber crop. Genetic manipulation continues to play a key role in the improvement of fiber quality properties. By use of DNA-based molecular markers and a polymorphic mapping population derived from an inter specific cross between TM-1 (G. hirsutum) and 3-79 (G. barbadense), thirteen quantitative trait loci (QTLs) controlling fiber quality properties were identified in 3-79, an extra long staple (ELS) cotton. Four QTLs influenced bundle fiber strength, three influenced fiber length, and six influenced fiber fineness. These QTLs were located on different chromosomes or linkage groups and collectively explained 30% to 60%of the total phenotypic variance for each fiber quality property in the F₂ population. The effects and modes of action for the individual QTLs were characterized with 3-79 alleles in TM-1 genetic background. The results indicated more recessive than dominant, with much less additive effect in the gene mode. Transgressive segregation was observed for fiber fineness that could be beneficial to improvement of this trait. Molecular markers linked to fiber quality QTLs would be most effective in marker-assisted selection (MAS) of these recessive alleles in cotton breeding programs. This revised version was published online in August 2006 with corrections to the Cover Date.     

Genetic detection of node of first fruiting branch in crosses of a cultivar with two exotic accessions of upland cotton

Flowering time has biological and agricultural significance for crops. In Upland cotton (Gossypium hirsutum L.), photoperiodic sensitivity is a major obstacle in the utilization of primitive accessions in breeding programs. Quantitative trait loci (QTLs) analysis was conducted in two F₂ populations from the crosses between a day-neutral cultivar Deltapine 61 (DPL61) and two photoperiod sensitive G. hirsutum accessions (T1107 and T1354). Node of first fruiting branch (NFB) was used to measure relative time of flowering. Different flowering time genetic patterns were observed in the two populations. Two QTLs were found across five scoring dates, accounting 28.5 (qNFB-c21-1) and 15.9% (qNFB-c25-1) of the phenotypic variation at the last scoring date in Pop. 1107 (DPL61 by T1107); whereas, one major QTL (qNFB-c25-1) can be detected across five scoring dates, explained 63.5% of the phenotypic variation at the last scoring date in Pop. 1354 (DPL61 by T1354). QTLs with minor effects appeared at various scoring date(s), indicating their roles in regulating flowering at a lower or higher node number. Genetic segregation analysis and QTL mapping results provide further information on the mechanisms of cotton photoperiodic sensitivity. Part of a Ph.D. dissertation by senior author submitted to the Department of Plant and Soil Sciences, Mississippi State University, December 2007. Contribution of USDA-ARS in cooperation with the Mississippi Agric. and Forestry Exp. Stn. Journal paper J. 11276 of Mississippi Agric. and Forestry Exp. Stn.     

Interspecific hybridization in Gossypium L.: characterization of progenies with different ploidy‐confirmed multigenomic backgrounds

Cytological and molecular investigations were undertaken for parent and progeny derived from a trispecific line [2(Gossypium arboreum × G. anomalum) × G. hirsutum var. BWR], which was crossed with G. hirsutum var. JLH168. Cytomorphological analysis of the F₁ (G. arboreum × G. anomalum), its amphidiploid and progeny from trispecies hybrid showed distorted ploidy segregation with monovalents to hexavalents and high intergenomic (small A₂ and large B₁) allosynthetic chromosome pairing. Microsatellite analysis identified three fragments associated with G. arboreum and G. anomalum and six fragments associated with G. hirsutum in derivates of the trispecies line × G. hirsutum var. JLH168. Inter‐Retrotransposon Amplified Polymorphism (IRAP) analysis revealed fragments of G. arboreum and G. anomalum, only in F₁ and amphidiploid. Chromosomal association and microsatellite analysis of three progeny genotypes (i.e. haploid, hexaploid and tetraploid no. 1) confirmed that they share multigenomic background from the three cotton species (A₂, A_hD_h and B₁ genome). The interspecific hybrid cotton genotypes studied are likely to be useful for the introgression of genes from diploid species to commercial upland cultivars.     

Genetic analysis of agronomic and fibre traits using four interspecific chromosome substitution lines in cotton

Backcrossed chromosome substitution lines (CS‐B) have been developed with a homologous pair of chromosomes or chromosome arms of Gossypium barbadense (3‐79) germplasm substituted for the homologous Gossypium hirsutum(TM‐1) chromosomes or chromosome segments. We report on agronomic and fibre trait performance of four backcrossed chromosome or chromosome arm substitution lines including chromosomes 01, 11sh (chromosome 11 short arm), 12 sh and 26 Lo (chromosome 26 long arm). Data for agronomic and fibre traits were collected from replicated field experiments at two different locations in 2 years, and analysed under an additive dominance genetic model. CS‐B 12sh had higher, while CS‐B 01 and CS‐B 26Lo had lower boll weight than TM‐1. The presence of significant negative additive effects for micronaire with CS‐B 01 and significant positive additive effects for elongation and fibre strength with CS‐B 11sh suggested the substituted chromosome arms of 3‐79 in these CS‐B lines were more likely carrying genes causing these effects. Results revealed that several CS‐B lines had significant homozygous and heterozygous dominance effects for different agronomic and fibre traits suggesting that specific CS‐B lines may be useful for improving agronomic and fibre traits in hybrid cottons. These CS‐B lines also provide novel genetic resources for improving upland cotton germplasm.     

Exploitation of the late flowering species <Emphasis Type="Italic">Brassica oleracea</Emphasis> L. for the improvement of earliness in <Emphasis Type="Italic">B. napus</Emphasis> L.: an untraditional approach

The oilseed Brassica rapa flowers and matures earlier than B. oleracea, as well as their amphidiploid B. napus. Therefore, earliness of B. rapa has been investigated as a source of variation for earliness in B. napus breeding programs. Variation for days to flower exists in B. oleracea; however, its earliest flowering variant B. alboglabra flowers 2–3 weeks later than B. napus. We hypothesized that the C genome of B. alboglabra carries alleles for early flowering which are different from the C-genome alleles of B. napus; and these alleles can be used for the improvement of B. napus. To test this, we examined flowering time in pedigree and DH populations from two B. napus × B. alboglabra crosses. A B. napus line with about a week earlier flowering than the B. napus parent was achieved through reconstitution of its C genome following pedigree selection. Introgression of the B. alboglabra allele in the early flowering pedigree lines is also evident from the presence of B. alboglabra-specific SSR alleles in this line. However, application of doubled haploidy failed to generate any line that flowered earlier than the B. napus parent, which is probably due to the difficulty of obtaining large numbers of euploid B. napus DH lines from this interspecific cross. Thus, we demonstrate that a trait of the diploid species, which apparently looks undesirable, might in fact be highly valuable for the improvement of amphidiploids; and knowledge from this research can also be applied for other traits.     

Morph-physiological responses of cotton interspecific chromosome substitution lines to low temperature and drought stresses

Limited knowledge about genetic and physiological traits associated with drought and low temperature stresses and narrow genetic diversity in Upland cotton (Gossypium hirsutum L.) are serious impediments in its genetic improvement. The objectives of this research were to determine the genetic and physiological traits associated with drought and low temperature effects and to identify chromosomal effects on these traits using chromosome substitution (CS) lines from three alien species of Gossypium, G. barbadense, G. tomentosum, and G. mustelinum, respectively. Two experiments were conducted to study low temperature and drought stress effects during seedling emergence and early growth stages in 21 cotton CS-lines with parent, Texas Marker (TM)-1. In Experiment I, plants were grown at optimum (30/22 °C) and low (22/14 °C) temperature conditions under optimum water and nutrient conditions. In Experiment II, plants were grown at optimum water (soil moisture content of 0.167 m³ m^?3) and in drought (soil moisture content 0.105 m³ m^?3) conditions under optimum temperature conditions. Above- and below-ground growth traits including several root traits of the CS lines were assessed at 25 days after sowing. The findings suggest which substituted chromosome or chromosome segment from the alien species likely harbors one or more genes for higher and lower tolerance to low temperature, respectively. CS-T04 and CSB08sh showed higher and lower tolerance to low temperature, respectively and CS-T04 and CS-B22sh showed higher and lower tolerance, respectively, to drought. CS lines are valuable analytical tool and useful genetic resources for targeted exploitation of beneficial genes for drought and low temperature stresses in Upland cotton.     

Induction of fertile flowers in potato (Solanum tuberosum L.) by silver thiosulphate anionic complex

Summary The effect of gibberellic acid containing mixtures, silver thiosulphate and extended photoperiod on flowering induction in 16 non-flowering potato genotypes and on flowering enhancement in 14 normally potato flowering genotypes was studied in sub-tropical plains of India during short-day autumn crop season of 2000–2001 and 2001–2002. Extended photoperiod alone was not successful in induction of flowering. Silver thiosulphate in combination with extended photoperiod effectively induced flowering in 16 potato genotypes studied for flowering induction. Induced flowers of some genotypes were male fertile. Normal berry setting was observed on induced flowers and seeds obtained from such berries germinated normally. Gibberellic acid containing treatments were not very effective in flower induction as they induced some flowering only in few genotypes. In the normally flowering genotypes silver thiosulphate enhanced maximum flowering and duration of flowering to a great extent.     

Evaluation of drought tolerance for Atlas fescue,perennial ryegrass,and their progeny

Primitive cottons (Gossypium spp.) represent resources for genetic improvement. Most primitive accessions are photoperiod sensitive; they do not flower under the long days of the U.S. cotton belt. Molecular markers were used to locate quantitative trait loci (QTLs) for node of first fruiting branch (NFB), a trait closely related to flowering time in cotton. An F₂ population consisted of 251 plants from the cross of a day neutral cultivar Deltapine 61, and a photoperiod sensitive accession Texas 701, were used in this study. Segregation in the population revealed the complex characteristics of NFB. Interval mapping and multiple QTL mapping were used to determine QTLs contributing to NFB. Three significant QTLs were mapped to chromosome 16, 21, and 25; two suggestive QTLs were mapped to chromosome 15 and 16. Four markers associated with these QTLs accounted for 33% of the variation in NFB by single and multiple-marker regression analyses. Two pairs of epistasis interaction between markers were detected. Our results suggested that at least three chromosomes contain factors associated with flowering time for this population with epistasis interactions between chromosomes. This research represent the first flowering time QTL mapping in cotton. Makers associated with flowering time may have the potential to facilitate day neutral conversion of accessions. Contribution of USDA-ARS in cooperation with the Mississippi Agric. and Forestry Exp. Stn. Journal paper J-11131 of Mississippi Agric. and Forestry Exp. Stn. Mention of trademark, proprietary product, or vendor does not constitute a guarantee or warranty of the product by USDA, ARS and does not imply its approval to the exclusion of other products or vendors that may also be suitable.