Understanding the crop diversity is critical for a successful breeding program, helping to dissect the genetic relationship among lines, and to identify superior parents. This study aimed to investigate the genetic diversity of maize (Zea mays L.) inbred lines and to verify the relationship between genetic diversity and heterotic patterns based on hybrid yield performance. A total of 1,041 maize inbred lines were genotyped-by-sequencing, generating 32,840 quality-filtered single nucleotide polymorphisms (SNPs). Diversity analyses were performed using the neighbor-joining clustering method, which generated diversity groups. The clustering of lines based on the diversity groups was compared with the predefined heterotic groups using the additive genomic relationship matrix and unweighted pair group method with arithmetic mean. Additionally, the genetic diversity of lines was correlated with yield performance of their corresponding 591 single-cross hybrids. The SNP-based genetic diversity analysis was efficient and reliable to assign lines within predefined heterotic groups. However, these genetic distances among inbred lines were not good predictors of the hybrid performance for grain yield, once a low but significant Pearson's correlation (.22, p-value ≤ .01) was obtained between parental genetic distances and adjusted means of hybrids. Thus, SNP-based genetic distances provided important insights for effective parental selection, avoiding crosses between genetically similar tropical maize lines.

Sorghum [Sorghum bicolor (L.) Moench] biomass hybrids with high productivity and enhanced levels of lignin are seen as a promising alternative of feedstock for direct burning in ovens designed for cogeneration of electricity. The objective of this study was to estimate the genetic combing capacity of biomass sorghum lines and conduct multivariable selection of photosensitive biomass sorghum hybrids for use in cogeneration. Thirty‐six photosensitive hybrids, the control BRS716, and 12 parental lines were evaluated in a seven‐by‐seven triple lattice design at two locations, and 12 characters were evaluated. There was superiority of additive effects on the genetic control of all the characteristics studied in both environments, less for female lines in the diallelic analysis of F1 hybrids. The inclusion of parents in the estimates of combining capacities indicated predominance of dominance effects involved in the genetic control of the traits analyzed. The results demonstrate the action of epistasis of the dwarf genes present in the female lines for the biomass parameter and the false interpretation when these lines are included in the diallelic analysis. With the use of the index based on factor analysis and genotype–ideotype distance (FAI‐BLUP index), four factors were established, which separated the characteristics of production and quality, as well as the two environments, resulting from the high hybrid × environment interaction. With the index, five hybrids with higher potential for burning (H5‐5, H2‐1, H1‐1, H1‐5, and H5‐1) were selected. However, no hybrids obtained gains for the characteristics of production and quality, simultaneously, which indicates the need for genetic improvement of the parents used in the program.

Sorghum breeding programs are based predominantly on developing homozygous lines to produce single cross hybrids, frequently with relatively narrow genetic bases. The adoption of complementary strategies, such as genetic diversity study, enables a broader vision of the genetic structure of the breeding germplasm. The purpose of this study was to evaluate the genetic diversity of sorghum breeding lines using structure analysis, principal components (PC) and clustering analyses. A total of 160 sorghum lines were genotyped with 29,649 SNP markers generated by genotyping-by-sequencing (GBS). The PC and clustering analyses consistently divided the R (restorer) and B (maintainer) lines based on their pedigree, generating four groups. Thirty-two B and 21 R lines were used to generate 121 single-cross hybrids, whose performances were compared based on the diversity clustering of each parental line. The genetic divergence of B and R lines indicated a potential for increasing heterotic response in the development of hybrids. The genetic distance was correlated to heterosis, allowing for the use of markers to create heterotic groups in sorghum.

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Native genetic resistance has been considered an effective and environmentally safe alternative to control fungal infections and to reduce mycotoxins accumulation in maize grains. Marker-assisted breeding can be used to accelerate the genetic gains for fumonisin contamination resistance. Thus, the objective of this study was to identify quantitative trait loci (QTLs) and candidate genes for resistance to fumonisin contamination in an Embrapa’s tropical maize panel. Two-hundred and five inbreed lines were evaluated in three field trials Brazil in order to quantify fumonisin contamination in maize grains. The lines were genotyped-by-sequencing (GBS), generating 385,654 high-quality polymorphic SNPs. Mycotoxins in the grain samples were isolated using commercial immunoaffinity columns and its concentrations were evaluated by fluorometric technique. Nine quantitative trait loci (QTL) were found associated with fumonisin concentration resistance in maize. Seven candidate genes with annotated functions associated with biosynthetic pathways of pathogen resistance and four genes have not been previously described as related to fumonisins contamination resistance. These findings will be important to better understand the fumonisin contamination resistance and to support the development of SNP markers to accelerate the selection process in tropical maize breeding programs.