LETTER Partial diallel crosses for predicting yield of semiexotic maize populations.

In Brazil, the total production of maize has increased continuously due to the advances in technology but also to the new frontiers for the maize crop, including the expansion of the second crop (safrinha; usually maize after soybean). Therefore, the exploitation of new sources of germplasm seems to be imperative to attend the actual and future demands for modern cultivars adapted to the greatly variable environments available to the maize crop. The present study was based on a partial diallel (intergroup) cross to provide quantitative information on the potential of two groups of varieties (NAP - exotics and HG - local) and their combining abilities to direct the synthesis of new populations to be used in hybrid crosses or as a base for breeding programs. The experiments were carried out in two planting seasons (safra - 1st crop; safrinha - 2nd crop) following the completely randomized block design with four replications of plots 5 m long spaced 0.9 m with 25 plants per plot after thinning. The following traits were analyzed: male flowering (days), stalk diameter (mm), plant height (m), ear height (m), tassel length (cm), tassel branch number, ear length (cm), ear diameter (cm), ear yield (t/ha), and grain yield (t/ha). The populations under study presented acceptable levels for yield potential and agronomic traits, thus assuring good perspectives for their use in breeding programs. The prediction for the new populations to be synthesized from the cross between the two groups of varieties contributed positively and HG-3 population was the most appropriate, in both eras, as the parent variety most promising in Group II (HG to be used as a base) for incorporation of varieties of Group I (NAP).

Validation of EST-derived microsatellite markers for two Cerrado-endemic Campomanesia (Myrtaceae) species.

We assessed the transferability of 120 EST-derived Eucalyptus microsatellite primers to Campomanesia adamantium and C. pubescens. Both species are berry trees native to the Brazilian Cerrado, and population genetic information is poor. Twelve markers were used to analyze the genetic variability of four sampled populations. Regarding DNA extraction, we sampled leaf tissues from two populations of each species (80 individuals). Of the 120 primers evaluated, 87 did not amplify any PCR products, and 21 rendered nonspecific amplification. Twelve primers were successfully transferred, providing a low combined probability of genetic identity for both species (5.718 x 10(-10) for C. adamantium; 1.182 x 10(-11) for C. pubescens) and a high probability of paternity exclusion (0.99939 for C. adamantium; 0.99982 for C. pubescens). The average number of alleles in the polymorphic loci was 6.8 for C. adamantium and 7.8 for C. pubescens, ranging from 2 to 16 alleles per locus. The observed heterozygosity values for C. adamantium and C. pubescens were 0.504 and 0.503, respectively, and the expected heterozygosity values for C. adamantium and C. pubescens were 0.517 and 0.579, respectively. The populations exhibited structured genetic variability with qP values of 0.105 for C. adamantium and 0.249 for C. pubescens. Thus, we concluded that these 12 microsatellite markers, transferred from Eucalyptus, were efficient for population genetic studies of C. adamantium and C. pubescens.

Variability and inbreeding in semiexotic maize populations.

Three semiexotic populations (CRE-01, CRE-02, CRE-03) obtained by incorporation of exotic germplasm (lines from CIMMYT, Colombia; selected for resistance to corn stunt complex) were evaluated in two cycles of recurrent selection with half-sib families. In cycle-I, samples comprising 50, 70, and 50 half-sib families were evaluated at Jataí (GO) and traits analyzed were ear yield, plant height, and ear height. For yield (t/ha), populations means were 5.86, 6.19, and 5.31, representing approximately 73% of hybrid check. Sets of parameters estimates representing the three populations were: [237, 485, and 608] for the additive genetic variance (σ(2)A: g/plant); [0.393, 0.584, 0.658] for the coefficient of heritability (h(2)m: progeny mean basis), and [0.464, 0.684, and 0.801] for the index of variation (θ). In cycle-II, materials analyzed included 60 non-inbred (half-sib) and 60 inbred (S1) families from each population, evaluated at Anhembi (SP) with two replications; traits analyzed included ear yield plus ear weight and grains weight of four ears, two plant traits (plant height and ear height), two ear traits (length and diameter), two tassel traits (branch number and length), and resistance to corn stunt complex. Means of half-sib families for ear yield (t/ha) were [10.614, 10.419, 10.842], representing 83 to 86% of the hybrid check. The same pattern of variation was observed for ear weight and grain weight of four ears. Means of S1 families were [6.465, 5.527, 5.925] and the inbreeding depression in percent of the non-inbred families were [39.1, 46.9, 45.3]. Estimates for other traits are also shown.

Genetic diversity of gabiroba based on random amplified polymorphic DNA markers and morphological characteristics.

The fragmentation of the original vegetation of the Cerrado biome, caused by the expansion of agricultural areas, mainly in central-west Brazil, calls for an assessment of the native population of this vegetation, especially of the species of interest for domestication and sustainable use. The purpose of this study was to characterize the genetic diversity of 140 gabiroba mother plants (Campomanesia spp) and their progenies from 17 locations in Goiás. The morphological characteristics of the mother plants were evaluated, and the leaflets were collected for molecular analysis using 12 random amplified polymorphic DNA primers. The seed progenies of these matrices were transplanted to the field and morphologically evaluated. Distance matrices of the morphological data of the mother plants and progenies as well as the molecular data of the mother plants were constructed, and groups were formed using the Tocher method and the unweighted pair-group method based on arithmetic averages. The polymorphism level in the matrix was 90.44%. The greatest molecular distance (0.66) was observed between mother plants from Santa Rita do Araguaia and Alexânia. By the Tocher method, 10, 13, and 17 groups were formed. The morphological evaluation of the mother plants and progenies as well as the molecular analysis of the mother plants showed genetic diversity. Significant genetic variability was detected in the progenies of the gabiroba base collection planted in Campus Jataí, Goiás.

Influência de desfolhas artificiais para simular perdas na produção do feijoeiro (Phaseolus vulgaris L. cv. Xamego) / Influence of artificial defoliation to simulate losses in production of beans (Phaseolus vulgaris L. cv. Xamego)

A redução da área foliar é uma das causas da queda de produção em feijoeiro comum. O objetivo deste trabalho foi verificar a influência de diferentes níveis de desfolha em vários estádios de desenvolvimento sobre a produtividade, massa de 100 sementes e número de vagens por planta do feijoeiro da cultivar Xamego, em condições de campo no Sul do Espírito Santo. Utilizou-se o delineamento em blocos casualizados, sendo as parcelas dispostas no esquema fatorial 5 x 4: cinco épocas de desfolha (1ª folha trifoliolada, florescimento, formação das vagens, enchimento das vagem, e vagens secas) x quatro níveis de remoção das folhas (0, 33, 67 e 100%), com cinco repetições. Houve decréscimo linear da produtividade com os níveis de desfolha em todos os estádios de desenvolvimento, com exceção ao de vagens secas, sendo este decréscimo maior no estádio de formação das vagens. Pela análise de regressão atribui-se maior redução da produtividade com 100% de desfolha feita aos 44 dias após emergência. O componente de rendimento mais correlacionado com a produtividade foi o número de vagens por planta.

The reduction of foliar area can cause yield reduction in common bean crops. The objective of this work was to ascertain the effect of different defoliation levels realized in several developmental stages of common beans (Phaseolus vulgaris L. cv. Xamego) in regard to yield, weight of 100 seeds and number of pods per plant. A randomized complete block design was used considering a two-way 5 x 4 factorial arrangement: (i) five defoliation stages (first trifoliate leaf, flowering, pods formation, pods filling, and dry pods), and (ii) four defoliation levels (0, 33, 67 and 100%). Five replications were carried out. A linear decrease of yield was observed for all defoliation levels considering all development stages, except for dried pods. The highest decrease was detected for pods formation. At 100% of defoliation, a higher decrease of yield was observed when it was done at 44 days after emergence. Regression analysis gave a greater reduction in yield with 100% defoliation done at 44 days after emergence. The evaluation parameter that showed the best correlation with yield was the number of pods per plant.

Infarto agudo do miocárdio em gêmeos. Aspectos genéticos / Acute myocardial infarction in twins.Genetic aspects

Os autores apresentam uma familia constituida por 13 elementos, na qual duas gemeas univitelinas, de 36 anos, negras, tiveram infarto agudo do miocardio.Analisam os fatores intrinsecos e extrinsecos envolvidos na genese da cardiopatia nas pacientes e dislipidemias em seus familiares, com a intencao de detectar fatores responsaveis por coronariopatias, contribuindo assim para a sua prevencao.Concluem pela evidente implicacao genetica e chamam a atencao para esta possibilidade, especialmente em familias com alta recorrencia de coronariopatia