Molecular dissection of interspecific variation between Gossypium hirsutum and G. barbadense (cotton) by a backcross-self approach: II. Fiber fineness

A backcross-self population from a cross between Gossypium hirsutum and G. barbadense was used to dissect the molecular basis of genetic variation governing two parameters reflecting lint fiber fineness and to compare the precision of these two measurements. By applying a detailed restriction fragment length polymorphism (RFLP) map to 3,662 BC₃F₂ plants from 24 independently derived BC₃ families, we were able to detect 32 and nine quantitative trait loci (QTLs) for fiber fineness and micronaire (MIC), respectively. The discovery of larger numbers of QTLs in this study than previously found in other studies based on F₂ populations grown in favorable environments reflects the ability of the backcross-self design to resolve smaller QTL effects. Although the two measurements differed dramatically in the number of QTLs detected, seven of the nine MIC QTLs were also associated with fiber fineness. This supports other data in suggesting that fiber fineness more accurately reflects the underlying physical properties of cotton fibers and, consequently, is a preferable trait for selection. Negative transgression, with the majority of BC₃F₂ families showing average phenotypes that were poorer than that of the inferior parent, suggests that many of the new gene combinations formed by interspecific hybridization are maladaptive and may contribute to the lack of progress in utilizing G. barbadense in conventional breeding programs to improve upland cotton.Electronic Supplementary Material Supplementary material is available for this article at     

Molecular dissection of phenotypic variation between Gossypium hirsutum and Gossypium barbadense (cotton) by a backcross-self approach: III. Fiber length

A backcross-self population from a cross between Gossypium hirsutum and G. barbadense was used to dissect the molecular basis of genetic variation governing 15 parameters that reflect fiber length. Applying a detailed restriction fragment length polymorphism (RFLP) map to 3,662 BC₃F₂ plants from 24 independently derived BC₃ families, we detected 28, nine, and eight quantitative trait loci (QTLs) for fiber length, length uniformity, and short fiber content, respectively. For eight, six, and two chromosomal regions containing quantitative trait loci (QTLs) for fiber length, length uniformity, and short fiber content (respectively), two-way analysis of variance showed a significant (P<0.001) among-family genotypic effect. A total of 13, two, and four loci showed genotype × family interaction, illustrating some of the complexities that are likely to be faced in introgression of exotic germplasm into the gene pool of cultivated cotton. Co-location of many QTLs for fiber length, length uniformity, and short fiber content accounted for correlations among these traits, while the discovery of many QTLs unique to each trait suggests that maximum genetic gain will require breeding efforts that target each trait (or an index including all three). The availability of DNA markers linked to G. barbadense QTLs identified in this and other studies promise to assist breeders in transferring and maintaining valuable traits from exotic sources during cultivar development.Electronic Supplementary Material Supplementary material is available for this article at     

Investigation of some yield and fibre quality characteristics of interspecific hybrid (Gossypium hirsutum L. x G. barbadense L.) cotton varieties

Interspecific hybrid cottons (Gossypium hirsutum L. x G. barbadense L.) have great both yield and quality potential. This study was conducted to determine potential yields and quality characteristics of hybrid cotton varieties in southeastern Anatolia region of Turkey. The experiment was set out a completely randomized block design with four replications during 2003 and 2004 at University of Dicle, Faculty of Agriculture Experimental Field. Seven interspecific hybrid cotton varieties (48-08, Sevilla, Europe, Ica, Etna, 14-08 and Acalpi) which were obtained from Israel, and commonly grown varieties in this region, non-hybrid cotton varieties, GW Teks and DP-Opal were used as the materials of the study. Difference among the cultivars was significant for all traits except sympodial branch. Maximum number of boll and lint yield was 20.18 n plant(-1) and 1685.8 kg ha(-1) from interspecific hybrid cotton Ica, while interspecific hybrid cotton Europe recorded the lowest number of boll and lint yield. Interspecific hybrid cotton varieties showed higher value for fibre length, fibre fineness and fibre strength than non-hybrid cotton varieties. The longest fibres were obtained from Acalpi and Etna (34.08 and 33.88 mm), while non-hybrid varieties, DP-Opal and GW-Teks, had the lowest fibre length, 28.50 and 30.03 mm, respectively. The finest fibres obtained from Ica and 48-08 (3.42 and 3.45 mic.), the strongest fibres from Etna and Acalpi (40.07 and 40.23 g tex(-1)), and most elongation fibres from Acalpi (8.00%) and Sevilla (7.45%). Lint yield correlated positive and significant with fiber length.     

A combined RFLP-SSR-AFLP map of tetraploid cotton based on a Gossypium hirsutum x Gossypium barbadense backcross population.

An interspecific Gossypium hirsutum x Gossypium barbadense backcross population of 75 BC1 plants was evaluated for 1014 markers. The map consists of 888 loci, including 465 AFLPs, 229 SSRs, 192 RFLPs, and 2 morphological markers, ordered in 37 linkage groups that represent most if not all of the 26 chromosomes, altogether spanning 4400 cM. Loci were not evenly distributed over linkage groups, and 18 of the 26 long groups had a single dense region. This paper proposes a partially revised list of the 13 pairs of homoeologous A/D chromosomes of the 2n = 4x = 52 tetraploid cotton genome. The major revisions, which involve the c3-c17, c4-c22, c5-D08, and c10-c20 homoeologous pairs, are based on the mapping of 68 SSR and RFLP loci with a known chromosome assignment, as well as on comparative alignments with previously published G. hirsutum x G. barbadense maps. The overall congruency in the locus orders and distances of common SSR and RFLP loci in these maps allows for an estimation of the consensus length that reaches a minimum of 5500 cM, and is encouraging for future efforts aimed at developing an integrated map of cultivated cotton. The present map also provides a firm framework for precision mapping of Mendelian components of quantitative traits in cotton     

Isolation,culture, and cell division in cotyledon protoplasts of cotton (Gossypium hirsutum and G. barbadense)

Protoplasts were isolated from cotyledons and foliage leaves of cotton (Gossypium hirsutum and G. barbadense). Cotyledon protoplasts were larger and responded to culture better than leaf protoplasts. Cotyledon derived protoplasts regenerated cell walls and formed microcolonies of 2–3 cells in G. hirsutum and 5–8 cells in G. barbadense. However, the microcolonies did not grow beyond this stage. Protoplast yield and viability, cell wall regeneration and cell division were influenced by several factors, e.g., genotype, age, tissue and growth condition of donor plant, enzyme mixture and concentration, preplasmolysis period, incubation period, and culture medium.Abbreviations 2,4-D 2,4-dichlorophenoxyacetic acid - NAA -naphthaleneacetic acid - BAP 6-benzylaminopurine - GA₃ gibberellic acid - p CPA p-chlorophenoxyacetic acid - MES 2[N-morpholino]ethanesulfonic acid     

利用海岛棉渐渗系改良陆地棉纤维品质

棉花是世界上种植最广泛的纤维作物,随着人们生活水平的提高和棉纺织工业的发展,对棉花的纤维品质提出了更高的要求.本研究利用渐渗系ZP171为亲本,该材料以陆地棉中棉所8号为遗传背景携带了纤维品质优异的海岛棉Pima90-53片段,构建遗传群体并选育优异种质材料.基于群体在多环境下的纤维品质鉴定结果,发现纤维长度和比强度与...     

Cotton Fiber Cell Walls of Gossypium hirsutum and Gossypium barbadense Have Differences Related to Loosely-Bound Xyloglucan

Cotton fiber is an important natural textile fiber due to its exceptional length and thickness. These properties arise largely through primary and secondary cell wall synthesis. The cotton fiber of commerce is a cellulosic secondary wall surrounded by a thin cuticulated primary wall, but there were only sparse details available about the polysaccharides in the fiber cell wall of any cotton species. In addition, Gossypium hirsutum (Gh) fiber was known to have an adhesive cotton fiber middle lamella (CFML) that joins adjacent fibers into tissue-like bundles, but it was unknown whether a CFML existed in other commercially important cotton fibers. We compared the cell wall chemistry over the time course of fiber development in Gh and Gossypium barbadense (Gb), the two most important commercial cotton species, when plants were grown in parallel in a highly controlled greenhouse. Under these growing conditions, the rate of early fiber elongation and the time of onset of secondary wall deposition were similar in fibers of the two species, but as expected the Gb fiber had a prolonged elongation period and developed higher quality compared to Gh fiber. The Gb fibers had a CFML, but it was not directly required for fiber elongation because Gb fiber continued to elongate rapidly after CFML hydrolysis. For both species, fiber at seven ages was extracted with four increasingly strong solvents, followed by analysis of cell wall matrix polysaccharide epitopes using antibody-based Glycome Profiling. Together with immunohistochemistry of fiber cross-sections, the data show that the CFML of Gb fiber contained lower levels of xyloglucan compared to Gh fiber. Xyloglucan endo-hydrolase activity was also higher in Gb fiber. In general, the data provide a rich picture of the similarities and differences in the cell wall structure of the two most important commercial cotton species.     

Genetic mapping of a cross between Gossypium hirsutum (cotton) and the Hawaiian endemic, Gossypium tomentosum

The existence of five tetraploid species that derive from a common polyploidization event about 1 million years ago makes Gossypium (cotton) an attractive genus in which to study polyploid evolution and offers opportunities for crop improvement through introgression. To date, only crosses (HB) between the cultivated tetraploid cottons Gossypium hirsutum and G. barbadense have been genetically mapped. Genetic analysis of a cross (HT) between G. hirsutum and the Hawaiian endemic G. tomentosum is reported here. Overall, chromosomal lengths are closely correlated between the HB and HT maps, although there is generally more recombination in HT, consistent with a closer relationship between the two species. Interspecific differences in local recombination rates are observed, perhaps involving a number of possible factors. Our data corroborate cytogenetic evidence that chromosome arm translocations have not played a role in the divergence of polyploid cottons. However, one terminal inversion on chromosome (chr.) 3 does appear to differentiate G. tomentosum from G. barbadense; a few other apparent differences in marker order fall near gaps in the HT map and/or lack the suppression of recombination expected of inversions, and thus remain uncertain. Genetic analysis of a discrete trait that is characteristic of G. tomentosum, nectarilessness, mapped not to the classically reported location on chr. 12 but to the homoeologous location on chr. 26. We propose some hypotheses for further study to explore this incongruity. Preliminary quantitative trait locus (QTL) analysis of this small population, albeit with a high probability of false negatives, suggests a different genetic control of leaf morphology in HT than in HB, which also warrants further investigation.     

Inheritance of stomatal conductance in cotton (Gossypium barbadense)

Stomatal conductance in improved Pima cotton cultivars (Gossypium barbadense) has been previously shown to be positively associated with heat resistance and yield potential. In the present study we determined the mode of inheritance of stomatal conductance in crosses of six G. barbadense parents varying in origin, degree of agronomic development and stomatal conductance. Parents included a primitive tropical cotton (B368), two obsolete cultivars (St Vincent V135, Pima 32), one modern commercial line (Pima S-6) and two elite genotypes of the Pima germplasm (P70, P73). These lines showed distinct differences in stomatal conductance, under greenhouse and field conditions. The primitive B368 had the lowest conductance, and the elite lines the highest. Generation means analysis was used to quantify genetic effects in the crosses P70 × St Vincent V135, Pima S-6 × B368, Pima S-6 × Pima 32, P73 × Pima 32 and P73 × Pima S-6. Best-fit models of the inheritance of stomatal conductance varied in complexity from a simple additive-dominance model in the cross P70 × St. Vincent V135 to models displaying digenic epistatic interactions in the remaining crosses. Significant additive mean effects for stomatal conductance were detected in all crosses. Dominance mean effects were significant in the crosses P73 × Pima 32 and P73 × Pima S-6. Broadsense heritability estimates of stomatal conductance were relatively low (0.16–0.44) in all crosses except Pima S-6 × B368 (0.74). Results also show that the mode of inheritance of stomatal conductance is multigenic, and may have maternal as well as nuclear components. Recouping higher stomatal conductance levels from genetically wider crosses appears feasible and could proceed at a moderate rate. Fixing higher levels of stomatal conductance in populations from crosses of elite germplasm may be more difficult because of the presence of dominant mean effects and digenic epistatic interactions.     

Molecular insight into cotton leaf curl geminivirus disease resistance in cultivated cotton (Gossypium hirsutum)

Cultivated cotton (Gossypium hirsutum) is the most important fibre crop in the world. Cotton leaf curl disease (CLCuD) is the major limiting factor and a threat to textile industry in India and Pakistan. All the local cotton cultivars exhibit moderate to no resistance against CLCuD. In this study, we evaluated an exotic cotton accession Mac7 as a resistance source to CLCuD by challenging it with viruliferous whiteflies and performing qPCR to evaluate the presence/absence and relative titre of CLCuD‐associated geminiviruses/betasatellites. The results indicated that replication of pathogenicity determinant betasatellite is significantly attenuated in Mac7 and probably responsible for resistance phenotype. Afterwards, to decipher the genetic basis of CLCuD resistance in Mac7, we performed RNA sequencing on CLCuD‐infested Mac7 and validated RNA‐Seq data with qPCR on 24 independent genes. We performed co‐expression network and pathway analysis for regulation of geminivirus/betasatellite‐interacting genes. We identified nine novel modules with 52 hubs of highly connected genes in network topology within the co‐expression network. Analysis of these hubs indicated the differential regulation of auxin stimulus and cellular localization pathways in response to CLCuD. We also analysed the differential regulation of geminivirus/betasatellite‐interacting genes in Mac7. We further performed the functional validation of selected candidate genes via virus‐induced gene silencing (VIGS). Finally, we evaluated the genomic context of resistance responsive genes and found that these genes are not specific to A or D sub‐genomes of G. hirsutum. These results have important implications in understanding CLCuD resistance mechanism and developing a durable resistance in cultivated cotton.     

Genetic diversity of sea-island cotton (Gossypium barbadense) revealed by mapped SSRs

In order to evaluate the genetic diversity of sea-island cotton (Gossypium barbadense), 237 commonly mapped SSR markers covering the cotton genome were used to genotype 56 sea-island cotton accessions. A total of 218 polymorphic primer pairs (91.98%) amplified 361 loci, with a mean of 1.66 loci. Polymorphism information content values of the SSR primers ranged from 0.035 to 0.862, with a mean of 0.320. The highest mean polymorphism information content value for the SSR motifs was from a compound motif (0.402), and for the chromosomes it was Chr10 (0.589); the highest ratio of polymorphic primers in Xinjiang accessions was from Chr21 (83.33%). Genetic diversity was high in Xinjiang accessions. AMOVA showed that variation was 8 and 92% among populations and within populations, respectively. The 56 sea-island accessions were divided into three groups in the UPGMA dendrogram: Xinhai5 was in the first group; accessions from Xinjiang, except the five main ones, were in the second group, and the other 34 accessions were in the third group. Accessions from the former Soviet Union and Xinjiang main accessions were closely related. Both PCA and UPGMA confirmed that Xinhai5 was distinct from the other accessions, and accessions from Xinjiang were in an independent group. Given the differences between principal components analysis and UPGMA results, it is necessary to combine molecular markers and pedigree information so that genetic diversity can be objectively analyzed.     

Quantitative trait loci mapping and genetic dissection for lint percentage in upland cotton (Gossypium hirsutum)

Lint percentage is an important character of cotton yield components and it is also correlated with cotton fibre development. In this study, we used a high lint percentage variety, Baimian1, and a low lint percentage, TM-1 genetic standard for Gossypium hirsutum, as parents to construct a mapping populations in upland cotton (G. hirsutum). A quantitative trait locus/loci (QTL) analysis of lint percentage was performed by using two mapping procedures; composite interval mapping (CIM), inclusive composite interval mapping (ICIM) and the F_2:3 populations in 2 years. Six main-effect QTL (M-QTL) for lint percentage (four significant and two suggestive) were detected in both years by CIM, and were located on chr. 3, chr. 19, chr. 26 and chr. 5/chr. 19. Of the six QTL, marker intervals and favourable gene sources of the significant M-QTL, qLP-3(2010) and qLP-3(2011) were consistent. These QTL were also detected by ICIM, and therefore, should preferentially be used for marker-assisted selection (MAS) of lint percentage. Another M-QTL, qLP-19(2010), was detected by two mapping procedures, and it could also be a candidate for MAS. We detected the interaction between two M-QTL and environment, and 11 epistatic QTL (E-QTL) and their interaction with environment by using ICIM. The study also found two EST-SSRs, NAU1187 and NAU1255, linked to M-QTL for lint percentage that could be candidate markers affecting cotton fibre development.     

Molecular characterization of an elicitor-responsive Armadillo repeat gene (GhARM) from cotton (Gossypium hirsutum)

Only a few Armadillo (ARM) repeat proteins have been characterized in plants where they appear to have diverse functions, including the regulation of defence responses. In this study, the identification, cloning and characterization of a gene, encoding an ARM repeat protein (GhARM), is described. GhARM exists as multiple copies in cotton, with an 1713 bp ORF encoding 570 amino acids. The predicted protein contains three consecutive ARM repeats within an Armadillo-type fold, with no other distinguishing domains. Sequence alignments and phylogenetic analysis revealed that GhARM has a high homology with other ARM proteins in plants. The predicted three dimensional model of GhARM displayed a characteristic right-handed superhelical twist. In silico analysis of the promoter sequence revealed that it contains several defence- and hormone-responsive cis-regulatory elements. Expression of GhARM was significantly down-regulated in response to treatment with a V. dahliae elicitor suggesting that GhARM may function as a negative-regulator of cotton defence signalling against V. dahliae. To date, GhARM is the only ARM repeat gene that has been completely sequenced and characterized in cotton.     

Genetic dissection of the introgressive genomic components from Gossypium barbadense L. that contribute to improved fiber quality in Gossypium hirsutum L.

We crossed Luyuan343, containing the Gossypium barbadense (GB) genomic component, with Lumianyan22, a high-yielding Gossypium hirsutum (GH) variety, to evaluate the introgressive exogenous genomic components that contribute to fiber quality in upland cotton. A total of 158 of 334 mapping simple sequence repeats (SSR) loci screened from 18,467 SSR primer pairs were identified as putative GB introgression loci. Twenty-four quantitative trait loci (QTLs) for fiber quality and lint percentage were detected by WinQTLCart 2.5 based on three phenotypic datasets collected over 2 years in two different locations. Of these QTLs, 20 were mapped in the introgression chromosomal regions; the GB alleles contributed to improved fiber quality at eight loci, which were located in the introgression segments of chromosome (Chr.) 3, Chr.7 and Chr.25. A total of eight digenic epistasis and nine significant QTL × environment (QE) interactions were identified by QTLNetwork-2.2. Fiber elongation was found to be most easily influenced by environment since all QTLs for this trait showed significant QE interaction with large effects. Fiber length, fiber strength, and lint percentage were scarcely affected by environment as no or minor QE interaction effects for these traits were detected. Genome-wide identification of the introgressive GB components and mapping of the fiber-related QTLs indentified in this study will be beneficial for the simultaneous marker-assistant selection of improved fiber quality and lint yield in upland cotton breeding.     

Delineation of interspecific epistasis on fiber quality traits in Gossypium hirsutum by ADAA analysis of intermated G. barbadense chromosome substitution lines

Genetic diversity is the foundation of any crop improvement program, but the most cultivated Upland cotton [Gossypium hirsutum L., 2n?=?52, genomic formula?2(AD)₁] has a very narrow gene pool resulting from its evolutionary origin and domestication history. Cultivars of this cotton species (G. hirsutum L.) are prized for their combination of exceptional yield, other agronomic traits, and good fiber properties, whereas the other cultivated 52-chromosome species, G. barbadense L. [2n?=?52, genomic formula?2(AD)₂], is widely regarded as having the opposite attributes. It has exceptionally good fiber qualities, but generally lower yield and less desirable agronomic traits. Breeders have long aspired to combine the best attributes of G. hirsutum and G. barbadense, but have had limited success. F₁ hybrids are readily created and largely fertile, so the limited success may be due to cryptic biological and technical challenges associated with the conventional methods of interspecific introgression. We have developed a complementary alternative approach for introgression based on chromosome substitution line, followed by increasingly sophisticated genetic analyses of chromosome-derived families to describe the inheritance and breeding values of the chromosome substitution lines. Here, we analyze fiber quality traits of progeny families from a partial diallel crossing scheme among selected chromosome substitution lines (CS-B lines). The results provide a more detailed and precise QTL dissection of fiber traits, and an opportunity to examine allelic interaction effects between two substituted chromosomes versus one substituted chromosome. This approach creates new germplasm based on pair wise combinations of quasi-isogenic chromosome substitutions. The relative genetic simplicity of two-chromosome interactions departs significantly from complex or RIL-based populations, in which huge numbers of loci are segregating in all 26 chromosome pairs. Data were analyzed according to the ADAA genetic model, which revealed significant additive, dominance, and additive-by-additive epistasis effects on all of the fiber quality traits associated with the substituted chromosome or chromosome arm of CS-B lines. Fiber of line 3-79, the donor parent for the substituted chromosomes, had the highest Upper Half Mean length (UHM), uniformity ratio, strength, elongation, and lowest micronaire among all parents and hybrids. CS-B16 and CS-B25 had significant additive effects for all fiber traits. Assuming a uniform genetic background of the CS-B lines, the comparative analysis of the double-heterozygous hybrid combinations (CS-B?×?CS-B) versus their respective single heterozygous combinations (CS-B?×?TM-1) demonstrated that interspecific epistatic effects between the genes in the chromosomes played a major role in most of the fiber quality traits. Results showed that fiber of several hybrids including CS-B16?×?CS-B22Lo, CS-B16?×?CS-B25 and CS-B16?×?TM-1 had significantly greater dominance effects for elongation and hybrid CS-B16?×?CS-B17 had higher fiber strength than their parental lines. Multiple antagonistic genetic effects were also present for fiber quality traits associated with most of the substituted chromosomes and chromosome arms. Results from this study highlight the vital importance of epistasis in fiber quality traits and detected novel effects of some cryptic beneficial alleles affecting fiber quality on the 3-79 chromosomes, whose effects were not detected in the 3-79 parental lines.     

Production and characterization of asymmetric hybrids between upland cotton Coker 201 (Gossypium hirsutum) and wild cotton (G. klozschianum Anderss)

Asymmetric somatic hybrids were obtained between Gossypium hirsutum Coker 201 and wild cotton G. klozschianum Anderss. An investigation on the effect of ultraviolet (UV) irradiation on donor protoplasts was carried out, and the lethal dose was determined to be 38.7 J cm⁻². We firstly screened the putative hybrids by the color of the calli produced, followed by morphological, cytological, and molecular analysis of putative hybrid plants. Most regenerated plants derived from fused protoplasts displayed a recipient-like morphology, while some showed an intermediate phenotype between Coker 201 and G. klozschianum. Chromosome numbers in these somatic hybrids ranged from 54 to 74. The hybrids were verified by random amplified polymorphic DNA (RAPD) and simple sequence repeat (SSR). Absence or co-existence of parents’ genome DNA fragments was identified through molecular analysis. The heredity of cytoplasm was investigated by cleaved amplified polymorphic sequence (CAPS) analysis using mitochondrial and chloroplast universal primer pairs. The results indicated that recombination and rearrangements might have occurred in some regions of mitochondria (mt) and chloroplast (cp) DNA. To our knowledge, this is the first report about asymmetric protoplast fusion in cotton, and the hybrids obtained would be useful for breeding programs.     

Inheritance of the fuzzless-lintless character in cotton (Gossypium hirsutum)

Summary A fuzzless-lintless mutant was identified in MCU.5 (Gossypium hirsutum) cotton in 1984. The inheritance of this character is reported in this paper. The fuzzless-lintless mutant was crossed with fuzzy-linted parents viz. MCU.5, MCU.7, Express Sindh (W), Piedmont Cleveland and Sindis Wild and the segregation pattern was studied in F₂ and BC₁F₁ generations. The segregation ratios for fuzzy-linted and fuzzless-lintless were 151 in the first cross, 631 in the second, third and fourth crosses and 2551 in the fifth cross. These ratios indicated that this character is controlled by 2–4 gene pairs, and the fuzzless-lintless character is a recessive to fuzzy-linted character. The chi-square test was significant only in the BC₁F₁ generation with MCU.7 and Express Sindh (W). The test revealed that the observed values deviated significantly from the expected ratio of 71, suggesting that this character is also influenced by modifier gene complex.