Resumo em Inglês:

Abstract The objective of this work was to map QTL for agronomic traits in a Brazilian soybean population. For this, 207 F2:3 progenies from the cross CS3035PTA276-1-5-2 x UFVS2012 were genotyped and cultivated in Viçosa-MG, using randomized block design with three replications. QTL detection was carried out by linear regression and composite interval mapping. Thirty molecular markers linked to QTL were detected by linear regression for the total of nine agronomic traits. QTL for SWP (seed weight per plant), W100S (weight of 100 seeds), NPP (number of pods per plant), and NSP (number of seeds per plant) were detected by composite interval mapping. Four QTL with additive effect are promising for marker-assisted selection (MAS). Particularly, the markers Satt155 and Satt300 could be useful in simultaneous selection for greater SWP, NPP, and NSP.

Resumo em Inglês:

Abstract Maize (Zea mays L.) inbred lines are under restricted use, protected by Patent and Plant Variety Protection (PVP) laws. Research objectives were i) to identify and validate heterotic groups and patterns, and ii) to determine if ex-PVP lines are useful for continued genetic progress in short-season environments. Three groups of crosses were made following North Carolina Mating Design II (NCII) including 12 NDSU, 24 ex-PVP lines, and seven current industry testers. Hybrids were planted in four different experiments at six ND environments following partially balanced lattice experimental designs in 2011 and 2012. Top heterotic patterns were selected based upon grain yield and other agronomic traits. Our research indicates most ex-PVP lines are genetically narrow and may not be immediately useful. Less protection (5-yr vs. 20-yr) might increase usefulness of ex-PVP lines. This change in intellectual property will allow public breeders to develop better versions of industry lines carrying known weaknesses.

Resumo em Inglês:

Abstract This study evaluated the mode of reproduction, the meiotic behavior and the pollen viability of three tetraploid plants (2n=4x=40) originated from somatic chromosome duplication of Paspalum notatum plants. The plant WKS 3 changed the mode of reproduction after duplication and became apomictic. The plants WKS 63 and WKS 92 confirmed sexual mode of reproduction identical to that of the original genotype. The analyzed plants presented meiotic abnormalities related to tetraploidy, and the chromosome pairing were variable, but it did not hinder the meiotic products, which were characterized by regular tetrads and satisfactory pollen fertility, ranging from 88.7 to 95.7%. Results show that all plants are meiotically stable and that they can be used in intraspecific crosses in the breeding program of Paspalum notatum.

Resumo em Inglês:

Abstract The objective of this study was to investigate the phenotypic and molecular variability in a F2 generation derived from a SCH (Second Cycle Hybrid) in order to detect QTLs for some fruit traits of tomato. Genome coverage at different levels was achieved by three types of molecular markers (polypeptides, sequence-related amplified polymorphism-SRAP and amplified restriction fragment polymorphism - AFLP). Different degrees of polymorphism were detected by SRAP and AFLP at the DNA structure level and also by polypeptides at the DNA expression level. The first two markers, associated with phenotypic variation, detected QTLs involved in important agronomic traits such as fruit shelf life, soluble solids content, pH, and titratable acidity. New gene blocks originated by recombination during the first cycle of crossing were detected. This study confirmed that the observed phenotypic differences represent a new gene rearrangement and that these new gene blocks are responsible for the presence of the genetic variability detected for these traits.

Resumo em Inglês:

Abstract The objective of this study was to identify superior parents for crosses and the best families to breed new clones of energy cane. The best-performing parents were RB867515, RB93509, KRAKATAU, IM76-228, IM76-229, and US85-1008. The heritability and accuracy values for the traits tons of cane per hectare, fiber, and sucrose content indicate high correlation between the predicted genotypic means and observed values, enabling efficient selection of the best cane energy families. The extensive genetic variation detected and the presence of promising seedlings in the selected segregating population indicate the possibility of using new crosses in some clones and even in future commercial plantings. It was possible to identify the best parents involved in the evaluated crosses, and to select, in the best families, seedlings with a high fiber and good sucrose content, seedlings with high fiber and low sugar content, as well as seedlings with the same fiber and sucrose contents as the current cultivars.

Resumo em Inglês:

Abstract Ancient wheats are increasingly considered as valuable resources for genes of interest which could be analyzed and introduced into cultivated varieties by genetic engineering technologies. The first stage of biotechnological crop improvement consists of successful in vitro plant regeneration. Twelve wheat germplasms with different genomic formulas (AA, AABB, AAGG, AABBDD, AADDGG genomes) were examined with the use of two explant types (immature vs. mature embryos). All of the tested germplasms were able to regenerate plants, although the morphogenic ability of immature embryos was higher. The highest rate of embryogenic/regenerable structure formation was found in immature embryo cultures of tetraploid species (T. polonicum, T. turgidum, T. carthlicum, and T. dicoccum) as well as of hexaploid T. spelta. At the same time, diploid einkorn wheat (T. monococcum) and polyploid species with G chromosomes (T. timopheevii and T. kiharae) were characterized by low embryogenesis and by the presence of albino plantlets among shoots.

Resumo em Inglês:

ABSTRACT Six cowpea genotypes and their F2 hybrid combinations were evaluated for general and specific combining ability. The Griffing's diallel cross design, Method 2, and mixed model B were used. The genotypes and hybrids differed statistically (p <0.01) for the 10 studied traits. With regard to the general and specific combining ability, there were statistical differences at 1% probability for all traits. The presence of additive and non-additive gene effects paves the way for breeding new hybrid cultivars. However, additive gene effects were predominant in the trait expression. Genotypes CE-542, CE-954 and CE-796 were identified as the most promising of the test group for inclusion in cowpea breeding programs.

Resumo em Inglês:

Abstract The objective of this study was to evaluate the stability and adaptability, using the method of harmonic means of the relative performance of genetic values and to estimate the genetic components of variance and average via mixed models of 14 genotypes of passion fruit in three environments. Data were obtained in a random block design with three replicates and nine plants per plot. For the hybrids in the final validation phase, the estimates of heritability and genetic gains in the evaluated environments showed good prospects for selection of superior genotypes. There was a pronounced effect of genotype-environment interaction (GxE) for all traits investigated except fruit length, percentage of pulp, soluble solids, titratable acidity and SS/TA ratio. The most stable and adaptable hybrids in the evaluated environments were BRS Gigante Amarelo, HFOP-09, H09-09, GP09-02, GP09-03 and BRS Sol do Cerrado.

Resumo em Inglês:

Abstract The software Selegen-REML/BLUP uses mixed models, and was developed to optimize the routine of plant breeding programs. It addresses the following plants categories: allogamous, automagous, of mixed mating system, and of clonal propagation. It considers several experimental designs, mating designs, genotype x environment interaction, experiments repeated over sites, repeated measures, progenies belonging to several populations, among other factors. The software adjusts effects, estimates variance components, genetic additive, dominance and genotypic values of individuals, genetic gain with selection, effective population size, and other parameters of interest to plant breeding. It allows testing the significance of the effects by means of likelihood ratio test (LRT) and analysis of deviance. It addresses continuous variables (linear models) and categorical variables (generalized linear models). Selegen-REML/BLUP is friendly, easy to use and interpret, and allows dealing efficiently with most of the situations in plant breeding. It is free and available at http://www.det.ufv.br/ppestbio/corpo_docente.php under the author's name.

Resumo em Inglês:

Abstract In cotton breeding programs, it is necessary to identify genotypes with predictable behavior on the length of fibers, and which are responsive to environmental variations, in specific or broad conditions. The aim of this study was to employ the methodology of mixed models for simultaneous selection of cotton genotypes with greater length of fibers, adaptability and stability. It was evaluated 36 lines in three trials located in Apodi (2013 and 2014) and Santa Helena (2013,) in a randomized block design with two replications. Genetic parameters were estimated by the restricted maximum likelihood/best linear unbiased predictor method (REML/BLUP) and the selection was based on the method of harmonic mean of the relative performance of genetic values. The genotypes CNPA 2012-55, CNPA 2012-58, CNPA 2012-62 and CNPA 2012-64 can be grown in all tested environments, since they gather greater length of fibers, stability and adaptability.

Resumo em Inglês:

Abstract This study aimed to evaluate the relationship between fruit traits and their direct and indirect effects on the content of ascorbic acid and carotenoids in peaches and nectarines. The traits fruit mass (FM); equatorial diameter (ED); suture diameter (SD); polar diameter (PD); pulp firmness (FIR); soluble solids (SS); titratable acidity (TA); SS/TA ratio; contents of ascorbic acid (AA) and carotenoids (CT); and skin and pulp color were evaluated in 28 peach cultivars, and two nectarine cultivars. The phenotypic correlation coefficients were estimated (rf), and after multicollinearity diagnosis, unfolding was carried out in direct and indirect effects of the explanatory variables in the response variable by using path analysis. The strongest correlations ​​were found between FM, SD, ED, and PD, and between carotenoid content and °h pulp. The traits considered in the path diagrams are not the main determinants of the ascorbic acid content. The yellow color of the pulp has the potential for indirect selection for carotenoid content.

Resumo em Inglês:

Abstract Studies of genetic diversity and structure are key elements in designing effective in situ and ex situ management plans, especially for species experiencing forest fragmentation. To investigate the level of genetic diversity in populations of Trichocentrum pumilum, eight polymorphic microsatellite loci were developed and used for genotyping 96 specimens from four disturbed populations. Low genetic diversity within populations was found (average number of alleles per locus ranging from 3.75 to 4.25, observed and expected heterozygosities from 0.238 to 0.333 and from 0.450 to 0.482, respectively). The fixation index () ranged from 0.35 to 0.47, with significant values for all populations. No genotypic disequilibrium was detected. A mixed breeding system was found through an apparent outcrossing rate estimate. Our results suggest that these microsatellite loci are suitable for genetic studies of this species, showing low within population genetic diversity and moderate structure for T. pumilum populations.

Resumo em Inglês:

Abstract IPR Aimoré is a new triticale cultivar that combines earliness and high yield. In Value for Cultivation and Use trials carried out in 33 environments, involving the main triticale producing states, IPR Aimoré surpassed 4% the controls means, with mean yield of 4.955 kg ha-1.

Resumo em Inglês:

Abstract The sugarcane varieties RB975201 and RB975242 were developed and released for harvest at the end of the season (late maturation) in the Central-South region of Brazil. In specific environments, these varieties were compared with commercial standards in sugar yield per area. They are resistant to major sugarcane diseases and present the Bru1 gene of resistance to brown rust.