Fiber-related Traits Research Articles

Association Mapping for Fiber-Related Traits and Digestibility in Alfalfa (Medicago sativa).

Association mapping is a powerful approach for exploring the molecular genetic basis of complex quantitative traits. An alfalfa (Medicago sativa) association panel comprised of 336 genotypes from 75 alfalfa accessions represented by four to eight genotypes for each accession. Each genotype was genotyped using 85 simple sequence repeat (SSR) markers and phenotyped for five fiber-related traits in four different environments. A model-based structure analysis was used to group all genotypes into two groups. Most of the genotypes have a low relative kinship (<0.3), suggesting population stratification not be an issue for association analysis. Generally, the Q + K model exhibited the best performance to eliminate the false associated positives. In total, 124 marker-trait associations were predicted (p < 0.005). Among these, eight associations were predicted in two environments repeatedly and 20 markers were predicted to be associated with multiple traits. These trait-associated markers will greatly help marker-assisted breeding programs to improve fiber-related quality traits in alfalfa.

COMBINING ABILITY FOR YIELD AND YIELD CONTRIBUTING CHARACTERS IN KENAF (Hibiscus cannabinus L.)

Combining ability in 6 x 6 half diallel crosses were estimated for yield and yield contributing characters in kenaf (Hibiscus cannabinus L.). Combining ability analysis revealed that mean square due to general combining ability (GCA) and specific combining ability (SCA) were significant for all the characters studied suggesting the presence of both additive and non-additive gene action for the inheritance of the concerned characters. The magnitude of GCA variance was considerably higher than that of SCA variance for days to 1st flowering, fibre weight per plant and 1000-seed weight indicating the importance of additive gene action for these traits. The other characters were preponderantly controlled by non-additive gene action. Ranking of parents on GCA performance indicated that parent P6 (Acc.2731) was the best general combiner for fibre yield and yield attributes. On the other hand, parents P2 (Acc.4197) and P3 (Acc.2922) were found to be the best for seed related traits. On SCA performance, the crosses P3 x P5, P1 x P6, P3 x P6 and P4 x P5 were found to be the best for fibre related traits, while the best specific crosses for seed related traits were P2 x P3 and P2 x P4. For the development of high fibre or seed yielding kenaf varieties, either pedigree selection method or recurrent breeding is suggested depending on the genetic behavior of the trait.DOI: http://dx.doi.org/10.3329/bjpbg.v24i1.16307

QTL for fibre-related traits in grain × sweet sorghum as a tool for the enhancement of sorghum as a biomass crop

Compared to maize and temperate grasses, sorghum has received less attention in terms of improving cell wall components. The objectives of this study were to identify quantitative trait loci (QTL) with main effects, epistatic and pleiotropic effects along with QTL×environment (QE) interactions controlling fibre-related traits in sorghum. Neutral detergent fibre (NDF), acid detergent fibre (ADF), acid detergent lignin (ADL), cellulose, hemicellulose, fresh leaf mass, stripped stalk mass, dry stalk mass, fresh biomass and dry biomass were analysed from a population of 188 grain×sweet sorghum recombinant inbred lines. A genetic map consisting of 157 DNA markers was constructed, and QTL were detected using composite interval mapping (CIM). CIM detected more than 5 additive QTL per trait explaining 7.1-24.7% of the phenotypic variation. Abundant co-localization of these QTL was observed across all chromosomes, and the highest cluster was identified on chromosome 6. Searching for candidate genes using the confidence interval of our QTL clusters reveals that these clusters might comprise a set of genes that are tightly linked. Some QTL showed multiple effects; however, the allele for each trait was favouring the parent with the increasing effect. QE interactions were observed for QTL showing multiple effects. Additive×additive interaction was observed for 7 out of 10 traits, indicating the importance of epistatic analysis. However, the phenotypic variation explained by digenic interactions was lower compared to the individual QTL. Our results indicate that various genetic components contribute to fibre-related traits and should be considered during the enhancement of sorghum for lignocellulosic biomass.

Genetic effects of introgression genomic components from Sea Island cotton (Gossypium barbadense L.) on fiber related traits in upland cotton (G. hirsutum L.)

The germplasm with exotic genomic components especially from Sea Island cotton (Gossypium barbadense L. Gb) is the dominant genetic resources to enhance fiber quality of upland cotton (G. hirsutum L., Gh). Due to low efficiency of phenotypic evaluation and selection on fiber quality, genetic dissection of favorable alleles using molecular markers is essential. Genetic dissection on putative Gb introgressions related to fiber traits were conducted by SSR markers with mapping populations derived from a cross between Luyuan343 (LY343), a superior fiber quality introgression line (IL) with genomic components from Gb, and an elite Upland cotton cv. Lumianyan#22 (LMY22). Among 82 polymorphic loci screened out from 4050 SSRs, 42 were identified as putative introgression alleles. A total of 29 fiber-related QTLs (23 for fiber quality and six for lint percentage) were detected and most of which clustered on the putative Gb introgression chromosomal segments of Chr.2, Chr.16, Chr.23 and Chr.25. As expected, a majority of favorable alleles of fiber quality QTLs (12/17, not considering the QTLs for fiber fineness) came from the IL parent and most of which (11/12) were conferred by the introgression genomic components while three of the six (3/6) favorable alleles for lint percentage came from the Gh parent. Validation of these QTLs using an F8 breeding population from the same cross made previously indicated that 13 out of 29 QTLs showed considerable stability. The results suggest that fiber quality improvement using the introgression components could be facilitated by marker-assisted selection in cotton breeding program.

Relationship between Yield, Fiber Length and other Fiber-Related Traits in Advanced Cotton Strains

The objective of this study was to determine the relationship between yield, fiber length and other fiber related traits in advanced cotton strains, derived from a cotton breeding program. The experiments were conducted in the Southeastern Anatolia Agricultural Research Institute’s experimental area according to randomized complete block design (RCBD) with four replications during 2007 and 2008 cotton growing season. In the study, 9 advanced cotton strains and 2 check varieties (‘GW-Teks’ and ‘Stoneville 468’) were used as plant materials. The results of the statistical analysis indicated that the advanced cotton strains had significant differences in terms of the investigated characteristics when compared to the check varieties. The highest seed cotton yield (4087.0 kg ha-1) and fiber yield (1632.2 kg ha-1) were obtained from ‘SET-34’ cotton strain which had acceptable fiber quality properties. However, the highest fiber length (32.33 mm) was obtained from ‘ERA-85’. The correlation analysis indicated that there were significant negative correlations between fiber length and seed cotton yield, lint yield and ginning percentage, while there were positive and significant correlations between fiber length and fiber strength.

Genetic Linkage Mapping and Analysis of Muscle Fiber-Related QTLs in Common Carp (Cyprinus carpio L.)

A genetic linkage map of common carp (Cyprinus carpio L.) was constructed using Type I and Type II microsatellite markers and a pseudo-testcross mapping strategy. The microsatellite markers were isolated from microsatellite-enriched genomic libraries and tested for their segregation in a full-sib mapping panel containing 92 individuals. A total of 161 microsatellite loci were mapped into 54 linkage groups. The total lengths of the female, male and consensus maps were 2,000, 946, and 1,852cM, with an average marker spacing of approximately 13, 7, and 11cM, respectively. Muscle fiber-related traits, including muscle fiber cross-section area and muscle fiber density, were mapped to the genetic map. Three QTLs for muscle fiber cross-section area and two QTLs for muscle fiber density were identified when considering both significant and suggestive QTL effects. The QTLs with largest effects for muscle fiber cross-section area and muscle fiber density were 21.9% and 18.9%, and they were located in LG3, respectively.

Finding heterosis for fiber traits in intervarietal crosses of cotton, Gossypium hirsutum L.

Raising yield and fiber quality of cotton through heterosis (hybrid vigor) has been an objective of plant breeders and scientists. Heterosis over mid parent for fiber-related traits was calculated in three crosses of cotton (Gossypium hirsutum L.) involving five cotton varieties, viz., CIM 506, CIM 702, CIM 443, FH 1000 and CIM 1100 being commercially grown in Pakistan. Heterosis was observed for all four characters. The cross CIM 443 × CIM 1100 showed maximum positive heterosis (8.57%) for ginning outturn (GOT) (%) followed by fineness (7.81%) and staple length (1.01%). Therefore, the cross CIM 506 × CIM 1100 appeared to be promising for providing potential breeding materials for further commercial exploitation of heterosis in Pakistan, and heterosis breeding has a great potential for increasing stagnant cotton yields around the world.

Genetic parameters and relationships between fibre and type traits in two breeds of Peruvian alpacas

Four fibre traits (fibre diameter, FD; coefficient of variation of FD, comfort factor; and standard deviation of FD) were jointly analysed with six subjectively scored type traits (fleece density, crimp, lock structure, head, coverage, and balance) in two breeds of Peruvian Altiplano alpaca (Suri, SU; and Huacayo, HU) to ascertain their genetic relationship. A total of 2405 fibre records and 2194 type scores were available for the HU breed whereas these figures were 709 for fibre records and 650 for type scores for the SU breed. Estimated heritabilities for fibre traits were moderate to high, ranging from 0.565 to 0.699 in the SU breed and from 0.255 to 0.417 in the HU breed. Genetic and permanent environmental correlations between fibre related traits were extremely similar across breeds suggesting that these traits are fairly the same. Heritabilities estimated for the type traits tended to be lower than those estimated for the fibre traits particularly in the SU breed (ranging from 0.173 to 0.272). Fibre and type traits were, in general, genetically poorly correlated except for crimp in the HU breed, which had favourable correlations, from moderate to high, for fibre traits. In Altiplano areas in which fibre performance recording could not be implemented, crimp scoring makes it feasible to carry out mass selection in the Huacayo breed and furthermore include rural communities in national or regional selection programmes.

Identification of associations between SSR markers and fiber traits in an exotic germplasm derived from multiple crosses among Gossypium tetraploid species

Genetic improvement in yield and fiber quality is needed for worldwide cotton production. Identification of molecular markers associated with fiber-related traits can facilitate selection for these traits in breeding. This study was designed to identify associations between SSR markers and fiber traits using an exotic germplasm population, species polycross (SP), derived from multiple crosses among Gossypium tetraploid species. The SP population underwent 11 generations of mixed random mating and selfing followed by 12 generations of selfing. A total of 260 lines were evaluated for fiber-related traits under three environments in 2005 and 2006. Large genotypic variance components in traits were identified relative to components of genotype x environment. Eighty-six primer pairs amplified a total of 314 polymorphic fragments among 260 lines. A total of 202 fragments with above 6% allele frequency were analyzed for associations. Fifty-nine markers were found to have a significant (P < 0.05, 0.01, or 0.001) association with six fiber traits. There were six groups identified within the population using structure analysis. Allele frequency divergence among six groups ranged from 0.11 to 0.27. Of the 59 marker-trait associations, 39 remained significant after correction for population structure and kinship using a mixed linear model. The effect of population sub-structure on associations was most significant in boll weight among the traits analyzed. The sub-structure among the SP lines may be caused by natural selection, the breeding method applied during development of inbred lines, and unknown factors. The identified marker-trait associations can be useful in breeding and help determine genetic mechanisms underlying interrelationships among fiber traits.

Construction of a genetic linkage map and QTL analysis of fiber-related traits in upland cotton (Gossypium hirsutum L.)

A genetic linkage map with 70 loci (55 SSR, 12 AFLP and 3 morphological loci) was constructed using 117 F2 plants obtained from a cross between two upland cotton cultivars Yumian 1 and T586, which have relatively high levels of DNA marker polymorphism and differ remarkably in fiber-related traits. The linkage map comprised of 20 linkage groups, covering 525 cM with an average distance of 7.5 cM between two markers, or approximately 11.8% of the recombination length of the cotton genome. The present genetic linkage map was used to identify and map the quantitative trait loci (QTLs) affecting lint percentage and fiber quality traits in 117 F2:3 family lines. Sixteen QTLs for lint percentage and fiber quality traits were identified in six linkage groups by multiple interval mapping: four QTLs for lint percentage, two QTLs for fiber 2.5% span length, three QTLs for fiber length uniformity, three QTLs for fiber strength, two QTLs for fiber elongation and two QTLs for micronaire reading. The QTL controlling fiber-related traits were mainly additive, and meanwhile including dominant and overdominant. Several QTLs affecting different fiber-related traits were detected within the same chromosome region, suggesting that genes controlling fiber traits may be linked or the result of pleiotropy.

Genetic mapping and QTL analysis of fiber-related traits in cotton ( Gossypium).

Cotton, the leading natural fiber crop, is largely produced by two primary cultivated allotetraploid species known as Upland or American cotton ( Gossypium hirsutum L.) and Pima or Egyptian cotton ( G. barbadense L.). The allotetraploid species diverged from each other and from their diploid progenitors (A or D genome) through selection and domestication after polyploidization. To analyze cotton AD genomes and dissect agronomic traits, we have developed a genetic map in an F2 population derived from interspecific hybrids between G. hirsutum L. cv. Acala-44 and G. barbadense L. cv. Pima S-7. A total of 392 genetic loci, including 333 amplified fragment length polymorphisms (AFLPs), 47 simple sequence repeats (SSRs), and 12 restriction fragment length polymorphisms (RFLPs), were mapped in 42 linkage groups, which span 3,287 cM and cover approximately 70% of the genome. Using chromosomal aneuploid interspecific hybrids and a set of 29 RFLP and SSR framework markers, we assigned 19 linkage groups involving 223 loci to 12 chromosomes. Comparing four pairs of homoeologous chromosomes, we found that with one exception linkage distances in the A-subgenome chromosomes were larger than those in their D-subgenome homoeologues, reflecting higher recombination frequencies and/or larger chromosomes in the A subgenome. Segregation distortion was observed in 30 out of 392 loci mapped in cotton. Moreover, approximately 29% of the RFLPs behaved as dominant loci, which may result from rapid genomic changes. The cotton genetic map was used for quantitative trait loci (QTL) analysis using composite interval mapping and permutation tests. We detected seven QTLs for six fiber-related traits; five of these were distributed among A-subgenome chromosomes, the genome donor of fiber traits. The detection of QTLs in both the A subgenome in this study and the D subgenome in a previous study suggests that fiber-related traits are controlled by the genes in homoeologous genomes, which are subjected to selection and domestication. Some chromosomes contain clusters of QTLs and presumably contribute to the large amount of phenotypic variation that is present for fiber-related traits.

Heritabilities and genetic and phenotypic parameters for gluteus medius muscle fibre type composition, fibre size and capillaries in purebred Spanish horses

Heritability and genetic correlation parameters for muscle fibre type composition, fibre size and capillaries of the gluteus medius muscle were estimated for purebred Spanish (Andalusian) horses using restricted maximum likelihood with an animal model. The data consisted of muscle biopsies (three samples per animal removed at different depths) from 4-year-old ( n=290) and older ( n=47, 8- to 23-year-old) purebred Spanish horses of both sexes (208 stallions and 129 mares). Heritabilities of muscle fibre type traits were moderate to low ( h 2=0.11 to 0.28). Heritabilities for type I fibres-related traits (fibre percentage, cross-sectional area and relative area, h 2=0.28±0.09, h 2=0.19±0.06 and h 2=0.23±0.09, respectively) were higher than those estimated for type II fibres-related traits ( h 2=0.11 to 0.17), but heritability for type IIX (fast glycolytic) fibre percentage was moderate ( h 2=0.25±0.09). Nevertheless, type I and type IIX fibre percentages were phenotypically ( r p=−0.86) and genetically ( r g=−0.36) negatively correlated. Both type I vs. type IIA and type IIA vs. type IIX were genetically negatively correlated ( r g=−0.48 and −0.85, respectively). Present data show that type I fibre-related traits are more heritable than type IIA and type IIX fibre properties. The phenotypic variability observed for these traits is largely explained by non-genetic factors (training, nutrition). As type I fibre percentage, cross-sectional area and relative area are directly correlated with success in endurance performance horses [Rivero et al., 1993; J. Appl. Physiol. 75:1758–1766], the inclusion of these traits in breeding programs of Andalusian horses could be of interest for early selection of appropriate sires and mares in order to improve the athletic endurance capacity of this breed.