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Highlights • Partial diallel analysis is promising for production of second-generation ethanol. • Treatment × environment interaction was observed for all the evaluated traits. • Genetic variability was detected between the lines A and R of biomass sorghum. • The pyramiding of favorable alleles, aim at the development of superior hybrids. Abstract Mutant genotypes of biomass sorghum for low lignin - bmr (brown midrib) and sensitive to photoperiod are interesting for the production of second-generation ethanol. This research aimed to estimate the combining ability between lines A and R of biomass sorghum, both carrying the bmr-6 allele, for bioenergy potential. Three male-sterile lines (A) and ten fertility restorative lines (R) were used, generating 30 hybrids bmr and sensitive to photoperiod. The 30 hybrids, their parents, and six controls were evaluated in a triple lattice design (7 × 7), in two experimental areas of Embrapa Maize and Sorghum, in Sete Lagoas and Nova Porteirinha (Minas Gerais). These lines were crossed in a partial diallel design, based on the Griffing IV model (1956) adapted for partial diallel by Miranda Filho and Geraldi (1984). The evaluated traits were: days to flowering (DTF, days after sowing), plant height (PH, m), fresh biomass yield (FBY, ton.ha−1), dry matter (DM, %), and dry matter yield (DMY, t. ha−1). In addition, the FAI-BLUP selection Index was used to assist the selection of hybrids that simultaneously meet favorable traits. Results revealed that treatments x environment interaction had a significant effect (p < 0.01) for all traits. Moreover, genetic variability was detected between lines A and R, which can be explored by the pyramiding of their favorable alleles, aiming at developing superior hybrids for the production of second-generation bioethanol. [ABSTRACT FROM AUTHOR]

Autogamous plant breeders obtain numerous populations annually, and in the progeny selection process, the merit of the population is not considered. Thus, it would be important to have a progeny selection index that includes not only the effects of progenies in the different generations but also the effects of populations in all the generations and the data from parents and the F1 and F2 generations simultaneously. The main objective of this paper was to develop a selection method that encompasses the entire structure of an autogamous plant breeding program including all the data as of the parents, the F1 and F2 generations, and also both the progeny and population effects in the F3 to F6 generations. To do so, a selection index (called selection index with parents, populations, progenies, and generations [SIPPPG]), which includes all these effects, was proposed. Estimators were also derived for computation of the contribution (through indirect heritabilities and selective accuracies) of each source of information for predicting the additive genetic value of the lines to be obtained at the end of the selection process. The new approach was assessed through numerical evaluation and a total index was also obtained using field data derived from a breeding program with the common bean crop. This new index yields gains in selection efficiency ranging from 5 to 28% depending on the relative magnitude of the genetic variation among populations. [ABSTRACT FROM AUTHOR]

Studies highlight the hypocotyl diameter (HD) as an effective indicator of plant architecture (PA). Here, we estimated the genetic gain based on HD to improve PA. Twenty populations of cycles zero (C0) and one (C1), both in the F4 generation, were evaluated for PA, grain yield (GY) and HD. Plants with thickest HD in C0 were intercrossed in a circulant diallel mating design. In cycle C1, an estimated genetic gain of 4.93% was achieved for PA and 4.95% for HD. The populations with the highest probability of breeding lines with a thicker HD belong to cycle C1, and this selection strategy did not alter the GY of the populations of this cycle. Thus, indirect selection based on HD is promising for breeding for common bean PA by recurrent mass selection. [ABSTRACT FROM AUTHOR]

Persistence may be defined as high sustained yield over multi-harvest. Genetic insights about persistence are essential to ensure the success of breeding programs and any biomass-based project. This paper focuses on assessing the biomass yield persistence for bioenergy purpose of 100 elephantgrass clones measured in six growth seasons in Brazil. To assess the clones' persistence, an index based on random regression models and genotype-ideotype distance was proposed. Results suggested the existence of wide genetic variability between elephantgrass clones, and that the yield trajectories along the harvests generate genetic insights into elephantgrass clones’ persistence and G x E interaction. A gene pool that acts over the biomass yield (regardless of the harvest) was detected, as well as other gene pools, which show differences on genes expression (these genes are the major responsible for clones’ persistence). The lower and higher clones’ persistence was discussed based on genome dosage effect and natural biological nitrogen fixation ability applied to bioenergy industry. The huge potential of energy crops necessarily is associated with genetic insights into persistence, so just this way, breeding programs could breed a new cultivar that fulfills the bioenergy industries. [ABSTRACT FROM AUTHOR]

Flowering is an important agronomic trait. Quantile regression (QR) can be used to fit models for all portions of a probability distribution. In Genome-wide association studies (GWAS), QR can estimate SNP (Single Nucleotide Polymorphism) effects on each quantile of interest. The objectives of this study were to estimate genetic parameters and to use QR to identify genomic regions for phenological traits (Days to first flower—DFF; Days for flowering—DTF; Days to end of flowering—DEF) in common bean. A total of 80 genotypes of common beans, with 3 replicates were raised at 4 locations and seasons. Plants were genotyped for 384 SNPs. Traditional single-SNP and 9 QR models, ranging from equally spaced quantiles (τ) 0.1 to 0.9, were used to associate SNPs to phenotype. Heritabilities were moderate high, ranging from 0.32 to 0.58. Genetic and phenotypic correlations were all high, averaging 0.66 and 0.98, respectively. Traditional single-SNP GWAS model was not able to find any SNP-trait association. On the other hand, when using QR methodology considering one extreme quantile (τ = 0.1) we found, respectively 1 and 7, significant SNPs associated for DFF and DTF. Significant SNPs were found on Pv01, Pv02, Pv03, Pv07, Pv10 and Pv11 chromosomes. We investigated potential candidate genes in the region around these significant SNPs. Three genes involved in the flowering pathways were identified, including Phvul.001G214500, Phvul.007G229300 and Phvul.010G142900.1 on Pv01, Pv07 and Pv10, respectively. These results indicate that GWAS-based QR was able to enhance the understanding on genetic architecture of phenological traits (DFF and DTF) in common bean. [ABSTRACT FROM AUTHOR]

The objective of this study was to estimate the genetic gain of two recurrent selection cycles in common bean breeding and identify families with the potential to generate superior lines. The base population, cycle zero (C0), was obtained by combining 20 carioca bean parents, populations with favorable phenotypes for several agronomically important traits. The parents were recombined in a circulant diallel scheme, in which each parent participated in two crosses, generating 20 populations. From these populations, families were derived and evaluated for three seasons in the generations F2:3, F2:4 and F2:5. The same procedures of recombination and evaluation in C0 were performed in cycle one (CI). The genetic gain for yield, estimated from the simultaneous evaluation of the 40 best families of each cycle, was 8.6%. Families with potential to generate superior lines to cultivar Pérola were identified, especially among the CI families. [ABSTRACT FROM AUTHOR]

This study was carried out for the purpose of estimating genetic progress after two cycles of recurrent selection in red bean breeding and of obtaining new lines. In cycle zero, F3:5 and F3:6 families were evaluated. In cycle one, the families were extracted in generation F5 and evaluated in generations F5:6 and F5:7. As the families were evaluated in different years and generations, the estimate of genetic progress was obtained by simultaneously evaluating the 30 best lines obtained at the end of each cycle in experiments conducted through three crop seasons. After two cycles of recurrent selection, genetic progress, in the mean value of the crop seasons, was 7.5% for grain yield, 7% for grain appearance, 33.4% for resistance to rust and 13.2% for resistance to angular leaf spot. Lines of red beans were obtained with potential for being included in future Value for Cultivation and Use (VCU) testing for Minas Gerais, Brazil. [ABSTRACT FROM AUTHOR]

Background: Phosphorus (P) fixation on aluminum (Al) and iron (Fe) oxides in soil clays restricts P availability for crops cultivated on highly weathered tropical soils, which are common in developing countries. Hence, P deficiency becomes a major obstacle for global food security. We used multi-trait quantitative trait loci (QTL) mapping to study the genetic architecture of P efficiency and to explore the importance of root traits on sorghum grain yield on a tropical low-P soil. Results: P acquisition efficiency was the most important component of P efficiency, and both traits were highly correlated with grain yield under low P availability. Root surface area was positively associated with grain yield. The guinea parent, SC283, contributed 58% of all favorable alleles detected by single-trait mapping. Multi-trait mapping detected 14 grain yield and/or root morphology QTLs. Tightly linked or pleiotropic QTL underlying the surface area of fine roots (1–2 mm in diameter) and grain yield were detected at positions 1–7 megabase pairs (Mb) and 71 Mb on chromosome 3, respectively, and a root diameter/grain yield QTL was detected at 7 Mb on chromosome 7. All these QTLs were near sorghum homologs of the rice serine/threonine kinase, OsPSTOL1. The SbPSTOL1 genes on chromosome 3, Sb03g006765 at 7 Mb and Sb03g031690 at 60 Mb were more highly expressed in SC283, which donated the favorable alleles at all QTLs found nearby SbPSTOL1 genes. The Al tolerance gene, SbMATE, may also influence a grain yield QTL on chromosome 3. Another PSTOL1-like gene, Sb07g02840, appears to enhance grain yield via small increases in root diameter. Co-localization analyses suggested a role for other genes, such as a sorghum homolog of the Arabidopsis ubiquitin-conjugating E2 enzyme, phosphate 2 (PHO2), on grain yield advantage conferred by the elite parent, BR007 allele. Conclusions: Genetic determinants conferring higher root surface area and slight increases in fine root diameter may favor P uptake, thereby enhancing grain yield under low-P availability in the soil. Molecular markers for SbPSTOL1 genes and for QTL increasing grain yield by non-root morphology-based mechanisms hold promise in breeding strategies aimed at developing sorghum cultivars adapted to low-P soils. [ABSTRACT FROM AUTHOR]