Abstract Hancornia speciosaGomes, a native fruit tree, plays an important socio-economic role in Brazil's traditional communities. The objective was to estimate the genetic structure of 176 individuals from eight locations in the Cerrado, Caatinga and Atlantic Forest biomes, based on six microsatellite markers. The analyzes revealed the formation of five population groups: A- Pernambuco, Paraíba and Sergipe (Atlantic Forest), B- Maranhão (Cerrado); both, var. speciosa, C- Bahia (Caatinga / Cerrado transition zone) and Ceará (Caatinga), D- Goiás (Cerrado) and E- Minas Gerais (Cerrado,) being groups C, D and E possibly var. pubescens. Most of the genetic variation is within the groups (65.61%, Fst = 0.34, p <0.001). Although group A had the highest Ho (0.66), it had a negative fixation index (f = -0.02), while the other had positive values. Our results revealed high levels of genetic diversity and provide support the development of more efficient conservation strategies for H. speciosa.

Abstract Repetitive DNA is an important component of eukaryotic genomes, accounting for more than 90% of the genome size of some species, including mobile elements and satellite DNA sequences. The aim of study was to characterize the genome of Hancornia speciosa Gomes using C-value genome size estimate and repetitive DNA sequences analysis. The genome size estimate was obtained by flow cytometry and the repetitive DNA sequences were accessed using graph-based clustering. Evolutionary relationships among species of Apocynaceae was obtained using reads of Catharanthus roseus L., Rhayza stricta Decne, and Asclepias syriaca L. from the NCBI and analyzed by graph-based clustering. The genome size estimates in two botanical varieties showed 2C-values ranging from 0.88 to 1.08 pg, indicating small genome size. Clusters representing repeats making up at least 0.01% of the genome revealed the proportion of repetitive DNA ranging from 19.87% (H. speciosa) to 51.674% (A. syriaca), of which the mobile elements were more abundant. Satellite DNA sequences were not found in H. speciosa and R. stricta, while at least one satellite was detected in C. roseus and A. syriaca, suggesting that the LTR retrotransposon Ty3/Gypsy/Chromovirus may have replaced the satellite DNA in H. speciosa and R. stricta.

Abstract This study reports the complete chloroplast sequences of three Spondias species. The genome sequences were obtained for Spondias tuberosa, Spondias bahienses, and Spondias mombin using the Illumina sequencing technology by a combination of de novo methods and a reference-guided assembly using Sapindus mukorossi as reference. The genomes of S. tuberosa, S. bahiensis, and S. mombin had 162,036, 162,218, and 162,302 bp, respectively. The coding regions exhibited 130 genes, including 34–35 tRNAs and 4 rRNAs. The results revealed synteny among the genomes, with high conservation in the gene order and content and CG content. The inverted repeat regions (IRA and IRB) and the large and small single copies were very similar among the three genomes. The phylogenomic analysis reported similar topologies as that of previous studies, which used partial chloroplast, wherein S. mombin was the first diverging lineage, while S. tuberosa and S. bahiensis were derived, indicating that the phylogenetic analysis using partial or complete genome produces similar results. In summary, (1) we presented the first complete chloroplast genome for the genus Spondias, (2) phylogenies analyzed using the complete chloroplast genomes revealed a robust phylogenetic topology for Spondias, and (3) gene order, content, and orientation in Spondias are highly conserved.

Abstract Brazil is the largest sugarcane producer in the world and, the main varieties grown in Brazil, known as RB cultivars, were developed by the Interinstitutional Network for the Development of the Sugar and Alcohol Sector (RIDESA) and are used in 58.9% of the planted area in Brazil. These varieties were obtained through intercrosses between genotypes from the Serra do Ouro germplasm bank and successive crosses with related genotypes may have increased the level of genetic similarity. The aim of the present study was to analyze the genetic base of the Serra do Ouro germplasm bank over the past decades using microsatellite molecular markers. The genetic similarity among varieties using all the markers ranged from 0.166 to 0.823, and regression analysis showed an increase in genetic similarity in the 1970s; however, a narrowing of the genetic base over the last five decades was not observed.

Abstract The genus Spondias (family Anacardiaceae) comprises 19 taxa, ten of which occur in Neotropical regions. Spondias bahiensis has been suggested to be a hybrid, although initial evidence does not support this hypothesis. The aim of this study was to test the hypothesis of the hybrid origin of S. bahiensis using high-throughput sequencing with single nucleotide polymorphism (SNP) analysis, characterization of intragenomic nuclear ribosomal DNA (nrDNA), and nuclear and chloroplast phylogenomic analyses. The SNP analysis revealed a high number of SNPs in the S. bahiensis genome, and with respect to nrDNA, S. bahiensis shared approximately half of the SNP alleles with S. tuberosa, but not with S. mombin. Combining the SNP analysis with nrDNA phylogeny confirmed the hybrid origin of S. bahiensis and put S. tuberosa as the female genitor. Considering the phylogeny of the genus Spondias and intraspecific SNPs in S. bahiensis, the putative male genitor is S. dulcis.

RESUMO: O objetivo do estudo foi analisar a expressão de genes de referência em cana-de-açúcar sob estresse hídrico. As cultivares RB72454 e RB72910 foram cultivadas em campo e os tratamentos controle e estresse foram aplicados após 135 dias. O estresse das plantas foi mensurado utilizando as variáveis fisiológicas: taxa fotossintética, transpiração e condutância estomática. Para cada repetição biológica, a expressão gênica foi conduzida usando PCR tempo real para os genes α-tubulina, β-tubulina, β-actina, ciclofilina, fator 1 de alongamento eucariótico, gliceraldeído 3-fosfato desidrogenase (GAPDH), histona H3 e ubiquitina. A estabilidade dos genes foi avaliada usando os softwares geNorm,NormFinder e BestKeeper. Entre os genes candidatos, GAPDH foi identificado como o mais estável nos três métodos de análises, indicando ser estável para estudos de expressão gênica em cana-de-açúcar sob estresse hídrico; seguindo o gene β-actina como o segundo mais estável. Os resultados concluem que os genes GAPDH e β-actina são indicados para normalização em expressão gênica relativa, associada com estresse hídrico em cana-de-açúcar.

ABSTRACT: The aim of this study was to analyze the expression of putative reference genes in sugarcane under drought stress. The varieties RB72454 and RB72910 were cultivated and the treatments control and drought stress applied to 135-day-old plants grown under field conditions. The stress level of the plants was measured by rate of photosynthesis, transpiration, and stomatal conductance. For each biological replicate, expression analyses were conducted using quantitative polymerase chain reaction for the genes α-tubulin, β-tubulin, β-actin, cyclophilin, eukaryotic elongation factor 1, glyceraldehyde 3-phosphate dehydrogenase (GAPDH), histone H3 and ubiquitin. Stability was evaluated using the geNorm, NormFinder, and BestKeeper software packages. Among the candidate genes, GAPDH was identified as the most stable in all software, indicating its suitability for gene expression studies in sugarcane undergoing drought stress; the gene β-actin was the second most stable. These findings suggest using GAPDH and β-actin for normalization in relative gene expression in sugarcane.

ABSTRACT Neoleucinodes elegantalis is an important tomato pest in Brazil, occurring throughout the country and resulting in economic losses in agriculture. In several species, biogeographic studies in Brazil indicate the structuring of populations, following the refuge model, with a split between the populations of the northeast and the southeast regions of Brazil. The objective of this work was to analyze the phylogeography of N. elegantalis in Brazil, understanding its population structure and the demographic patterns. Larvae were collected from eight locations throughout Brazil, and the mitochondrial cytochrome c oxidase subunit 1 gene was analyzed. A total of 628 bp in 51 individuals were obtained, showing 12 haplotypes with a haplotype diversity of 0.836. Spatial analysis of molecular variance (SAMOVA) and cluster analysis showed two populations, indicating population structuring between individuals from the northeast (population 1) and southeast (population 2) regions of Brazil. Phylogenetic analysis indicated that the clades corresponding to the groups defined by SAMOVA have a divergence time of 0.2–0.5 million years, suggesting isolation during climatic events and a separation of the two populations coinciding with the predicted refuges to the Atlantic forest.

Abstract Drought is a major factor in decreased sugarcane productivity because of the resulting morphophysiological effects that it causes. Gene expression studies that have examined the influence of water stress in sugarcane have yielded divergent results, indicating the absence of a fixed pattern of changes in gene expression. In this work, we investigated the expression profiles of 12 genes in the leaves of a drought-tolerant genotype (RB72910) of sugarcane and compared the results with those of other studies. The genotype was subjected to 80–100% water availability (control condition) and 0–20% water availability (simulated drought). To analyze the physiological status, the SPAD index, Fv/Fm ratio, net photosynthesis (A), stomatal conductance (gs) and stomatal transpiration (E) were measured. Total RNA was extracted from leaves and the expression of SAMDC, ZmPIP2-1 protein, ZmTIP4-2 protein, WIP protein, LTP protein, histone H3, DNAj, ferredoxin I, β-tubulin, photosystem I, gene 1 and gene 2 was analyzed by quantitative real-time PCR (RT-PCR). Important differences in the expression profiles of these genes were observed when compared with other genotypes, suggesting that complex defense mechanisms are activated in response to water stress. However, there was no recognizable pattern for the changes in expression of the different proteins associated with tolerance to drought stress.

Cultivars of sugarcane (Saccharum) are hybrids between species S. officinarum (x = 10, 2n = 8x = 80) and S. spontaneum (x=8,2n=5-16x =40-128). These accessions have 100 to 130 chromosomes, 80-85% of which are derived from S. officinarum, 10-15% from S. spontaneum, and 5-10% are possible recombinants between the two genomes. The aim of this study was to analyze the repetition of DNA sequences in S. officinarum and S. spontaneum. For this purpose, genomic DNA from S. officinarum was digested with restriction enzymes and the fragments cloned. Sixty-eight fragments, approximately 500 bp, were cloned, sequenced and had their identity analyzed in NCBI, and in the rice, maize, and sorghum genome databases using BLAST. Twelve clones containing partial transposable elements, one single-copy control, one DNA repetitive clone control and two genome controls were analyzed by DNA hybridization on membrane, using genomic probes from S. officinarum and S. spontaneum. The hybridization experiment revealed that six TEs had a similar repetitive DNA pattern in the genomes of S. officinarum and S. spontaneum, while six TEs were more abundant in the genome of S. officinarum. We concluded that the species S. officinarum and S. spontaneum have differential accumulation LTR retrotransposon families, suggesting distinct insertion or modification patterns.

O armazenamento de pólen é uma importante ferramenta para programas de melhoramento de milho, permitindo preservar, sob condições artificiais, a viabilidade de gametas masculinos e ampliar as possibilidades de cruzamentos, independente da época do florescimento das variedades genitoras. O presente trabalho teve como objetivo avaliar meios de cultivo para a germinação in vitro de pólen de milho e analisar condições de conservação. Para avaliar viabilidade, foram testados seis meios de cultivo, contendo sacarose, ácido bórico, cloreto de cálcio hidratado e ágar. Para a conservação de pólen foram analisadas duas temperaturas (4 ºC e -20 ºC) e dois agentes desidratantes de pólen (sílica gel e cloreto de cálcio hidratado). Os altos valores de viabilidade do pólen no período de até 30 dias de armazenamento indicam que a desidratação em sílica gel e armazenamento a 4 ºC conservam a viabilidade de pólen de milho. O meio de cultivo que proporcionou a maior taxa de germinação in vitro foi com a composição de 0,7% de ágar, 17% de sacarose, 0,01% de ácido bórico e 0,03% de cloreto de cálcio hidratado.

The storage of pollen can be considered an important tool for maize breeding programs, allowing to preserve, under artificial conditions, the viability of male gametes and extend the possibilities of crossings regardless of flowering time of parental varieties. This study aimed to evaluate the culture media for in vitro germination of corn pollen and analyze storage conditions. To examine viability, six different culture media containing sucrose, boric acid, calcium chloride and agar were evaluated. For pollen preservation, two temperatures (4 ºC and -20 ºC) and two agents of pollen dehydration (silica gel and hydrated calcium chloride) were evaluated. The high values of pollen viability up to 30 days of storage indicate that dehydration in silica gel and storage at 4 ºC preserve the viability of corn pollen. The culture medium that provided the highest germination rate in vitro was the composition of 0.7% agar, 17% sucrose, 0.01% boric acid and 0.03% calcium chloride hydrate.

Espécies silvestres são fontes importantes de variabilidade genética e podem ser exploradas pelos programas de melhoramento. Cruzamentos entre teosinto e milho ocorrem naturalmente, e o teosinto pode ser utilizado como fonte de caracteres agronômicos para introdução em milho. O objetivo deste estudo foi estimar a variabilidade genética entre e dentro de populações de milho e teosinto (Zea mays mexicana). Duas populações de milho doce (BR400 e BR402), duas de milho comum (Suwan e Pampa) e uma de teosinto foram analisadas utilizando-se marcadores microssatélites. Os resultados indicaram que 64,5% da variação foi detectada dentro das populações, sugerindo a possibilidade de obtenção de progresso genético através da seleção dentro de cada população. A análise de 25 locos microssatélites permitiu identificar 92 alelos, com uma média de 3,7 alelos por loco. O percentual de locos polimórficos variou de 64% nas populações BR400 e Pampa a 80% na população de teosinto. A distância genética estimada confirmou a similaridade genética entre milho e teosinto.

Wild species are important sources of genetic variability and may be exploited by breeding programs. Crosses between teosinte and maize occur freely and teosinte serves as genetic source of agronomic traits for introduction in maize. The objective of this study was to estimate genetic variability among and within maize and teosinte populations (Zea mays mexicana). Two sweet maize populations (BR400 and BR402), two common maize populations (Suwan and Pampa) and one teosinte population were analyzed using microsatellites markers. Results indicated that 64,5% of the variation was detected within the populations, suggesting the possibility of obtaining genetic progress by selection within each population. The analysis with 25 microsatellites loci enabled the identification of 92 alleles with a mean of 3.7 alleles per locus. The average Polymorphism Information Content (PIC) was 0.52. The percentage of polymorphic loci varied from 64% in the BR400 and Pampa populations to 80% in the teosinte population. The estimated genetic distance confirmed the genomic similarity of maize and teosinte.