Paulo Augusto Vianna Barroso

Meta-analysis of cotton fiber quality QTLs across diverse environments in a Gossypium hirsutum x G. barbadense RIL population

BackgroundCotton fibers (produced by Gossypium species) are the premier natural fibers for textile production. The two tetraploid species, G. barbadense (Gb) and G. hirsutum (Gh), differ significantly in their fiber properties, the former having much longer, finer and stronger fibers that are highly prized. A better understanding of the genetics and underlying biological causes of these differences will aid further improvement of cotton quality through breeding and biotechnology. We evaluated an inter-specific Gh × Gb recombinant inbred line (RIL) population for fiber characteristics in 11 independent experiments under field and glasshouse conditions. Sites were located on 4 continents and 5 countries and some locations were analyzed over multiple years.ResultsThe RIL population displayed a large variability for all major fiber traits. QTL analyses were performed on a per-site basis by composite interval mapping. Among the 651 putative QTLs (LOD > 2), 167 had a LOD exceeding permutation based thresholds. Coincidence in QTL location across data sets was assessed for the fiber trait categories strength, elongation, length, length uniformity, fineness/maturity, and color. A meta-analysis of more than a thousand putative QTLs was conducted with MetaQTL software to integrate QTL data from the RIL and 3 backcross populations (from the same parents) and to compare them with the literature. Although the global level of congruence across experiments and populations was generally moderate, the QTL clustering was possible for 30 trait x chromosome combinations (5 traits in 19 different chromosomes) where an effective co-localization of unidirectional (similar sign of additivity) QTLs from at least 5 different data sets was observed. Most consistent meta-clusters were identified for fiber color on chromosomes c6, c8 and c25, fineness on c15, and fiber length on c3.ConclusionsMeta-analysis provided a reliable means of integrating phenotypic and genetic mapping data across multiple populations and environments for complex fiber traits. The consistent chromosomal regions contributing to fiber quality traits constitute good candidates for the further dissection of the genetic and genomic factors underlying important fiber characteristics, and for marker-assisted selection.

In situ conservation and genetic diversity of three populations of Gossypium mustelinum Miers ex Watt

Gossypium mustelinum Miers ex Watt is a native from Northeastern Brazil and belongs to the primary gene pool of the cultivated cotton. The unique places where the species was known to occur were visited to plan ex situ and in situ preservation. Two populations at Caicó became extinct, and only eleven individuals were found. At Jaguarari, although one population became extinct, a new one was localized with approximately 500 adult plants, where a fence avoided cattle feeding. The population from Macururé consisted of 28 plants protected from animals by thorns of Bromelia laciniosa Mart. ex Schult. f. Thirteen SSR primer pairs amplified 40 alleles, among which 30% were exclusive of one of the populations. The genetic differences between populations represented 58.3% of the total genetic variation observed. The high genetic distances are likely to be caused by geographical isolation as well as by the small number of individuals which contribute to new generations, and consequential genetic drift.

Concentrações de ANA e BAP na micropropagação de abacaxizeiro L. Merrill (Ananas comosus) e no cultivo hidropônico das plântulas obtidas in vitro

The effect of different ANA and BAP concentrations on in vitro and hydroponic cultures were studied. Pineapple shoots derived from Perola explants variety were inoculated in MS media containing BAP and ANA in different concentrations. Growth parameters of shoots and plantlets were measured for in vitro and hydroponic cultures. Showed a highest multiplication rates of shoots and consequently highest fresh matter production were obtained with BAP and ANA at the concentrations of 1,0 and 0,5 mg L-1 respectively. However, the shoot length as well as the root number formed were higher in the T2 (0,5 de BAP + 0,25 de ANA) and T3 (0,25 de BAP + 0,12 de ANA) treatments. The results showed that after sixty days of hydroponic culture and in the presence of T1 treatment, all plantlets had good developing that was observed in the majority of morphological growth parameters evaluated. The results showed that it is possible to obtain high quantities of shoots and then plantlets which could be cultivated in hydroponic culture using the pineapple micropropagation procedures methods.

In situ and genetic characterization of Gossypium barbadense populations from the states of Pará and Amapá, Brazil

The objective of this work was to characterize the populations of Gossypium barbadense in the states of Amapa and Para, Brazil. In situ characterization was conducted through interviews with the owners of the plants and environmental observations. Leaf or petal tissue as well as seed samples were collected for genetic characterization by single sequence repeats markers and for storage in germplasm banks, respectively. The plants were maintained in dooryards and used mainly for medical purposes. The genetic analysis showed no heterozygous plants at the loci tested ( f = 1), indicating that reproduction occurs mainly through selfi ng. The total genetic diversity was high (H e = 0.39); and a high level of differentiation was observed between cotton plants from the two states (F ST = 0.36). Conventional methods of in situ maintenance of G. barbadense populations are not applicable. The conservation of the genetic variability of populations present in the two states could be achieved through germplasm collection and establishing of ex situ seed banks. Index term: cotton, genetic diversity, germplasm, SSR markers.

Predicting performance of soybean populations using genetic distances estimated with RAPD markers

Abstract In order to verify whether genetic distance (GD) is associated with population mean (PM), genetic variance (GV) andthe proportion of superior progenies generated by each cross in advanced generations of selfing (PS), the geneticdistances between eight soybean lines (five adapted and three non-adapted) were estimated using 213 polymorphicRAPD markers. The genetic distances were partitioned according to Griffing’s Model I Method 4 for diallel analysis,i.e.,GD ij =GD+ GGD i + GGD j + SGD ij . Phenotypic data were recorded for seed yield and plant height for 25 out of 28populations of a diallel set derived from the eight soybean lines and evaluated from F 2:8 to F 2:11 generations. Nosignificant correlation for seed yield was detected between GD and GV, while negative correlations were detectedbetween GD and PM and between GD and PS (r = -0.74** and -0.75**, respectively). Similar results were observedfor the correlation between GGD i + GGD j and PM and between GGD i + GGD j and PS (r = -0.78** and -0.80**,respectively). No significant correlation was detected for plant height. The magnitudes of the correlations for seedyield were high enough to allow predictions of the potential of the populations based on RAPD markers.

Efeito do cultivo in vitro na presença de NaCl em plantas de abacaxizeiro na fase de aclimatação

3 Depto. de GenOtica e Biologia Celular, UFRN 4 Embrapa Semi-`rido Resumo: A cultura de tecidos tem sido utilizada como ferramenta para gerar e selecionar variabilidade genOtica que confira maior toler‚ncia das espOcies cultivadas ‡ salinidade. Plantas de abacaxi das variedades POrola e Smooth Cayenne foram micropropagadas em meio de cultura contendo zero, 12,5 e 25 mM de NaCl e avaliadas durante a fase de aclimataAao quanto ‡s alteraAies induzidas pelo NaCl durante o cultivo in vitro e para determinar o melhor par‚metro para quantificar estas alteraAies. Foram avaliados os caracteres altura das plantas, di‚metro da roseta foliar, nœmero de folhas, comprimento e largura da folha eDi aos 0, 15, 45, 75 e 105 dias apUs a instalaAao do experimento. Observou-se que as plantas micropropagadas em meio com NaCl e sem NaCl apresentaram mOdias e taxas de crescimento semelhantes, mas diferiram quanto ‡s correlaAies entre os caracteres e ‡s vari‚ncias fenotIpicas. Os resultados indicaram que a vari‚ncia fenotIpica foi o par‚metro mais adequado para avaliar o impacto da seleAao in vitro sobre caracteres aparentemente nao relacionados com a salinidade em plantas de abacaxi. Palavras-chave: Ananas comosus, cultura de tecidos, salinidade Effects of in vitro culture in the presence of NaCl in pineapple plants during the acclimatization phase Abstract: Plant tissue culture has been used to induce and select genetic variability in order to increase the level of salinity tolerance in several species. Pineapple plants from POrola and Smooth Cayenne varieties were micropropagated for six months in a medium with 0, 12.5 and 25 mM of NaCl and evaluated during the acclimatization phase to verify the changes induced by NaCl during in vitro cultivation and to determine the best parameter to quantify these changes. The traits evaluated for plant height, plant diameter, leaf number, length and width of the D leaf at 0, 15, 45, 75 and 105 days after the installation of the experiment. There was no effect of different levels of NaCl during the micropropagation on the traits and mean growing rates. Differences were found in the correlation coefficients between the characters and mainly, in the phenotypic variances. The results indicated that the phenotypic variances were more adequate to evaluate the impact of in vitro selection for NaCl tolerance on traits apparently not related to salinity in pineapple plants.

Distância genética entre linhagens avançadas de germoplasma de algodão com uso de marcadores de RAPD e microssatélites

The objective of this work was to select similarity coefficients to be used among sets of cotton genotypes with low genetic diversity. Sixty-five lineages and four cotton cultivars were analyzed by RAPD and SSR markers; and the genetic similarity was estimated by seven similarity coefficients: Simple Matching, Rogers & Tanimoto, Ochiai, Hamman, Jaccard, Dice and Russel & Rao. The adequacy of the use of each coefficient to the collected data was verified by correlation between the distance matrices, the consensus index between the dendrograms and the Tochers optimization method. The coefficient of Russel & Rao was the most divergent, and its use is not recommended. Among the parameters used to estimate the quality of information provided by each coefficient, differences were observed only by the consensus index, which established two groups: one in which simultaneous absence of bands are taken into account, and other in which it is excluded. Considering the presence of only two microsatellite alleles per polymorphic locus and the higher consensus index coefficients, the Simple Matching, Hamman and Rogers & Tanimoto coefficients should be preferred when analyzing cotton elite genotypes with low genetic similarity.

BRS 336: a high-quality fiber upland cotton cultivar for Brazilian savanna and semi-arid conditions

Cotton cultivar BRS 336 is a high-quality fiber upland cultivar and has wide adaptation to the Brazilian growing areas, with resistance to bacterial blight. BRS 336 exhibited fiber length higher than 32.0 mm in all field tests. Also, fiber strength exceeded all upland cotton currently grown in Brazil.

Seleção massal e porcentagem de fibra em cultivar de algodoeiro colorido

Algodoeiros de fibras coloridas apresentam qualidade inferior em relacao aos de fibra branca, alem de menor potencial de rendimento, porque, comparados aos brancos, os coloridos foram pouco explorados em termos de melhoramento genetico. Este trabalho teve como objetivo avaliar o efeito da selecao massal para porcentagem de fibra alta, media e baixa, dentro de uma populacao da cultivar BRS Verde, lancada em 2003. Quinhentas plantas da cultivar BRS Verde foram colhidas ao acaso e estratificadas em quatro classes quanto a porcentagem de fibra. As sementes de cada classe foram misturadas e participaram de um ensaio em blocos ao acaso com quatro tratamentos, mais a populacao original e quatro repeticoes. Ficou evidenciada a eficiencia da selecao massal em alterar a media das populacoes selecionadas e o ganho de selecao foi de 11% quanto a porcentagem de fibra.

A SSR marker linked to the B 12 gene that confers resistance to race 18 of Xanthomonas axonopodis pv. malvacearum in cotton is also associated with other bacterial blight resistance gene complexes

The SSR marker CIR246, which is linked to the B12 gene that confers resistance to race 18 of Xanthomonas axonopodis pv. malvacearum (Xam), was used to evaluate a series of cotton germplasms that were also tested for their response to inoculation with race 18 of Xam (S-295, Delta Opal, 101-102B, Guazuncho-2, Acala 44, Mebane B1, and Stoneville 2B-S9). The allele associated with resistance was amplified in genotypes that carry the B12 gene (S-295 and Delta Opal) as well as in those that carry B2B3 (101-102B) and B9LB10L (Guazuncho-2), indicating that the molecular marker is able to identify genotypes resistant to the Xam races up to race 18, with resistance genes other than B12.