Resumo em Inglês:

Abstract The aims of this study were to estimate genetic parameters, predict genotypic values, and analyze the genotypic divergence in S0 and S1 peach trees evaluated in a subtropical environment by the mixed model methodology. For this, twenty-two clones were evaluated for plant and fruit traits. Genotypic variance among clones was significant. The individual broad-sense heritabilities ranged from 0.11 to 0.84, and the individual repeatability coefficients ranged from 0.15 to 0.89. The genotypic coefficients of variation were higher than 10% for most of the traits. Clustering based on plant and fruit traits led to the formation of two and five mutually exclusive groups, respectively. Multivariate analysis of principal components indicated that some traits could be excluded from genetic evaluation. Considering the yield trait and the selection of five clones, predicted gain from selection was 70%, which shows the possibility of considerable genetic progress from clonal selection in peach trees.

Resumo em Inglês:

Abstract Leaf spinescence in pineapple plants was evaluated in a total of 2.014 F1 individuals as follows: 1.125 plants of the progeny of the Imperial BRS cv. × Pérola cv. cross, and 889 plants of the progeny of the Pico de Rosa cv. × BRS Imperial cv. cross. The genetic hypothesis with two loci and epistatic interaction of the piping (P) over spiny (S) trait was tested. The chi-square test was performed on deviations between the observed and expected numbers based on the genetic hypotheses formulated. The “BRS Imperial” × “Pérola” and “Pico de Rosa” × “BRS Imperial” progenies segregated into 1:0:1 (spineless:spiny tip:spiny), expressing phenotypes of their respective parents. The spineless leaf (“BRS Imperial”) is determined by the “Ppss” genotype, with the locus “P” in heterozygosity and the locus “S” in recessive homozygosity. The spiny leaf margin (“Pérola” and “Pico de Rosa”) is controlled by the “ppss” genotype.

Resumo em Inglês:

Abstract Spike fertility index (SF) is a trait easily measured at maturity and strongly associated with the number of grains per unit area. In order to identify genomic regions involved in SF control, a biparental (Baguette 10 × Klein Chajá) population of 80 recombinant inbred lines (RIL) was used. Seven field trails were conducted to determine the SF BLUP value per RIL. RILs were genotyped using a commercial chip (Axiom® 35K SNP Wheat Breeder's Array, Affimetrix). A linkage map was constructed with 857 SNP markers, and SF QTL mapping was performed. The narrow-sense heritability of SF was 0.89. Three genomic regions (QTL) associated with SF were found on chromosomes 2D, 4A, and 7A. The proportion of genetic variation explained by these three QTL was 32%, with no significant epistatic interaction between QTL.

Resumo em Inglês:

Abstract Cassava (Manihot esculenta Crantz) is worldwide the sixth-largest food crop and highly drought resistant. The expression of the myeloblastosis (MYB) family protein MeMYB26 in cassava was previously reported to be significantly up-regulated under water deficit. To study the basic characterization, natural variations and potential functions of MeMYB26 for drought resistance in cassava, the protein was subjected to bioinformatics analysis, multiplex-PCR with next-generation sequencing and candidate association studies. The results indicated that MeMYB26 is a typical transcription factor, with two MYB DNA-binding and transcriptional activation domains. One stop-gained and five nonsynonymous variations in the genomic region of MeMYB26 were significantly associated with drought resistance traits. The results of the scale-free coexpression network showed that the MeMYB26 gene plays a critical role in plant stress resistance, growth and biomass development. It was concluded that MeMYB26 is a reliable candidate gene associated with drought tolerance and biomass storage in cassava.

Resumo em Inglês:

Abstract The agricultural yield of sugarcane (Saccharum spp.) is influenced by various abiotic stresses, including aluminum toxicity (Al3+). MicroRNAs (miRNAs) play a role in plant tolerance to such stresses by modulating the expression of several important target genes involved in plant growth. This study investigated the possible tolerance mechanisms of two sugarcane genotypes (CTC-2 and RB855453) under Al3+ stress through miRNA expression profiles and in silico analysis of target genes. The expression data obtained using RT-qPCR and co-expression network analysis identified two possible regulatory mechanisms in the tolerant genotype (CTC-2) under Al3+ stress. miR395 was involved in Al3+ detoxification, whereas miR160, miR6225-5p, and miR167 participated in the process of lateral root formation, conferring tolerance to the genotype. These findings might be useful for biotechnological strategies that aim for miRNA silencing or gene overexpression and provide subsidies for future genetic improvement programs aimed at the development of abiotic stress-tolerant sugarcane genotypes.

Resumo em Inglês:

Abstract The aims of this study were to evaluate the homology of the ZmMATE1 and ZmMATE2 gene sequences with those deposited in the international banks of sequences and quantify the differential expression of the genes ZmMATE1, ZmMATE2, and ZmNrat1 in germplasms of landrace and hybrid maize under aluminum (Al) stress in minimal solution. Fifty-two hybrids from different companies and 50 landrace varieties were genotyped for the genes ZmMATE1 and ZmMATE2. For studies of gene expression, the tolerant (H 44 and V 18) and the sensitive (H 22 and V 25) genotypes were exposed to minimal solution containing 4 mg L-1 of Al for different periods (0, 1, 3, 6, 9, 12, 24, and 48 h). The results showed greater differential expression in the tolerant V 18 landrace variety of the gene ZmMATE1, indicating that exudation of citrate may be the main mechanism of Al tolerance in this genotype.

Resumo em Inglês:

Abstract Potato virus Y (PVY) is one of the main diseases of tobacco (Nicotiana tabacum). Recent studies indicated that the Va gene (Ntab0942120) determines the susceptibility of the crop to PVY, and that the Va gene product interacts with the PVY genome-linked protein (VPg) to initiate the PVY genome translation process, which ultimately leads to the systemic infection of tobacco by the virus. In this research, tobacco cultivar LJ911 was used as receptor material for gene editing. Gene Va was knocked out through CRISPR/Cas9 technology, and transgene-free homozygous edited plants in the T1 generation were established. Pathology tests indicated that the edited plants had gained PVY resistance. Therefore, the edited materials generated in this study represent potentially useful genetic resources for breeding of PVY- resistant tobacco.

Resumo em Inglês:

Abstract Brazilian potato production is based on cultivars originating from the USA and Europe; however, these cultivars were developed under different environmental conditions than those found in Brazil. The aim of this study was to evaluate the adaptability and stability of 18 potato clones (MLG), developed by the Universidade Federal de Lavras, and four cultivars in six environments in the state of Minas Gerais, Brazil. The following traits were evaluated: marketable tuber yield (MTY), specific gravity (SG), and tuber appearance (TA). Clones, environments, and the genotype × environment interaction had significant effects on all traits. The GGE-biplot explained 71.78, 98.13, and 62.86 % of the sum of squares from the G+G×E for MTY, SG, and TA, respectively. Three MLG clones had higher adaptability and stability, as well as better performance, than the cultivars, making them good candidates for release as cultivars.

Resumo em Inglês:

Abstract The potato tuber moth (Phthorimaea operculella Zeller) (PTM) is a destructive potato pest. Bacillus thuringiensis cry genes encode crystal proteins that have toxic characteristics against PTM. The aim of the present study was to develop a PTM resistant potato cv. Agria using the synthetic Bt cry1Ab gene. The transformation vector was constructed by inserting the cry1Ab gene into the pBI121 binary expression vector. The Agrobacterium tumefaciens strain AGL1 harboring the pBI35SCry1Ab construct was used for potato transformation. The results indicated that out of 97 putative transformed lines, 30 lines were PCR positive. Southern blot analysis revealed that one to three copies of transgenes were inserted into transgenic lines. The immunoassay test revealed the expression of the Cry protein. Furthermore, the results of bioassays confirmed the high mortality level of neonate larvae. The results of this study suggested that the transgenic lines have significant potential in pest control.

Resumo em Inglês:

Abstract The genotype × environment (G×E) interaction plays an essential role in phenotypic expression and can lead to difficulties in genotypes recommendation. Thus, the objectives of this study were: i) propose the Multi-Environment Index Based on Factor Analysis and Ideotype-Design/Markov Chain Monte Carlo (FAI/MCMC index), and ii) apply it for soybean genotypes recommendation. To this end, a data set with 30 soybean genotypes evaluated in 10 environments for grain yield trait was used. Variance components, genetic parameters and genetic values were estimated through MCMC algorithm. Environmental stratification was conducted by factor analyses and the selection of soybean genotypes was performed using the FAI/MCMC index. The results indicated the existence of genotypic variability and G×E interaction. The environments were grouped into three factors. The predicted genetic gains from indirect selection was 4.81%. Thus, our results suggest that the FAI/MCMC index can be successfully used in soybean breeding.

Resumo em Inglês:

Abstract Interspecific crosses between the more than 520 Passiflora species may or may not be compatible. The sequences ITS, matK, psbA-trnH, rbcL and trnL-F were used to confirm species identity and to estimate the genetic distances among 48 Passiflora accessions of a germplasm bank. Twenty species were used for crosses within and between distinct Passiflora subgenera. The phylogenetic resolution based on ITS data was superior to that of any single chloroplast marker, recommending it as a DNA barcode for this genus. However, the tree topology based on Bayesian phylogenetic analysis using the combination of the four chloroplast markers possessed greater support for subclades within the subgenus Passiflora, which contains more species of interest for breeders. We could not identify a clear cutoff value of pairwise Kimura two-parameter (K2P) distances to predict success or failure of crosses. Rather, the clustering of species pairs together within the same or closely related phylogenetic subclades predicted the probability of wide cross compatibility more reliably.

Resumo em Inglês:

Abstract Advances in genotyping technologies have transformed the way breeding programs manage their genetic resources. The identification of single nucleotide polymorphisms (SNPs) can improve understanding of the genetic diversity of maize (Zea mays) inbred lines and their classification into heterotic groups, which is useful in determining certain crosses to obtain hybrids with higher yield performance. The genetic diversity of 293 inbred lines was investigated with 5252 SNPs with minor allele frequency (MAF)>5%. There was an average of 525 SNPs per chromosome. Polymorphism information content (PIC) averaged 0.297. The unweighted pair group method with arithmetic mean analysis (UPGMA) and principal component analysis (PCA) based on the genetic distance matrix revealed four similar clusters and high cophenetic correlation coefficients (0.953 and 0.863, respectively). The results showed consistency between genetic distance-based grouping and the heterotic groups previously established using pedigree and topcross information for the inbred lines studied.

Resumo em Inglês:

Abstract In comparison to tomato plants without the dwarfism gene, dwarf tomato plants were shorter, had a smaller canopy diameter and remained upright during maturation, thereby reducing the fruit-soil contact, resulting in healthier fruits. This study evaluated tomato families of a BC1F3 population carrying the dwarf gene for industrial yield. The 150 BC1F3 families and the two parents (hybrid H-9889 and accession BGH-9889) as controls were assessed in an augmented block design with four replications. The data were subjected to variance analysis and the F test. A selection index, based on the sum of ranks of Mulamba and Mock (1978), was used for the selection of genotypes, considering the most relevant traits, i.e., canopy diameter, yield, lodging and fruit firmness. Thus, selection resulted in a yield gain of 8.04%.