Cláusio Antônio Ferreira de Melo

Melon has great economic importance in Brazil, and flower development is the basis for fruit and seed production. The objective of this study was to elucidate the variability of flowering characteristics and to compare qualitative and quantitative reproductive variations in relation to pollen viability and stigmatic receptivity in 21 genotypes, which includes 15 Brazilian accessions. In addition, we evaluated the influence of time on the growth of the pollen tube and its arrival at the ovule in vivo at different intervals (1 h, 2 h, 3 h) after hand pollination in three commercial varieties, one exotic accession, and two intervarietal hybrids, by epifluorescence technique. Three groups were distributed by the clustering method of Scott–Knott at 5% probability; group III included only commercial varieties for the flower width descriptor. C. melo germplasm presented 81% andromonoecious plants and 19% trimonoecious plants. Through the multivariate strategy, these 21 genotypes were distributed into six groups with distinct reproductive characteristics, and male flowering was accelerated compared to female flowering. Regarding pollen viability, it was greater than 95% according to staining methods. Pollen germination rate in vivo was affected by time, with an almost 12.5% increase between 1 h and 3 h after hand pollination, and the in vivo pollen germination in hybrids was lower than in commercial varieties. Brazilian accessions, despite stability in pollen viability and stigma receptivity, have great differences in reproductive terms, such as variations in the quantitative and qualitative characteristics of floral pieces and flowering. This work contributes to the knowledge on varieties, hybrids, exotic accession, and Brazilian melon germplasm by characterizing some of their main agricultural traits, such as reproduction floral biology, and opens up prospects for yield evaluation in plant breeding programs.

In June 2022, anthracnose was detected on the leaves of Annona muricata L. (soursop) in Ibirapitanga, Bahia, Brazil. To identify the pathogens, diseased leaves were surface sterilized and cultured on potato dextrose agar, resulting in the selection of two isolates, IBIRA-P5R2 and IBIRA-P2F1R2, which were used for further analysis. IBIRA-P5R2 exhibited gray to white mycelium with dark conidiomata, cylindrical conidia, and dark appressoria. In contrast, IBIRA-P2F1R2 exhibited dense, pale gray mycelium with distinct conidial and ascospore characteristics. Genetic analysis involved sequencing three regions: Internal Transcribed Spacer (ITS), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), and actin (ACT), with results deposited in GenBank. BLAST analysis revealed that IBIRA-P5R2’s sequences were 95.45% similar to Colletotrichum karstii, while IBIRA-P2F1R2’s sequences were 99.06% identical to . Colletotrichum fructicolaPathogenicity tests confirmed that both isolates caused anthracnose symptoms in soursop seedlings, with dark spots developing on leaves after three days. The pathogens were reisolated from infected leaves, confirming the same cultural and morphological traits as the original isolates. This study marks the firstrecorded occurrence of C. karstii and C. fructicola causing anthracnose on soursop in Bahia, Brazil. The findings aim to inform soursop farmers about this emerging disease, highlighting the need for tailored integrated management strategies to address different plant pathogens effectively.

Passiflora species are prized and grown as ornamental plants due to their stunning blooms. P. triloba has a unique petal count within the genus and remarkable flowers. To obtain cytogenetic and pollen data for this wild species, the following were performed: (i) karyotype and CMA3/DAPI banding; (ii) meiotic and post-meiotic analyses; (iii) pollen viability and in vitro pollen germination; and (iv) in vivo pollination. The species is diploid, with 2n = 2x = 18, and n = 9. The karyotype showed only metacentric chromosomes and CMA+ and DAPI– blocks in all centromeres and in the terminal regions of two chromosome pairs, indicating two pairs of satellites. Meiotic analysis revealed a low percentage of irregularities such as early and lagging chromosomes, asynchrony, and transverse spindle fibers. There was a predominance of interstitial chiasmata with a recombination index of 18.88. In the post-meiotic analysis, few irregularities such as dyads and triads were found, and the meiotic index was 99.08%. Pollen viability was 80.54%, but non-viable pollen grains were also observed with contracted cytoplasm (0.38%), empty (9.9%), pulverized (8.44%), and micrograin (0.64%), while 31.88% of pollen grains emitted pollen tubes after in vitro germination testing. Pollen tube emission and fertilization occurred within 2 hours of in vivo pollination. The cytogenetic and pollen analyses in this study indicate that P. triloba has the chromosome number typical of the Passiflora subgenus, regular meiotic behavior, high pollen viability, and the ability to emit pollen tubes and achieve fertilization, supporting its potential use in interspecific hybridization.

Characterizing and predicting genetic diversity within the genus Passiflora is critical for promoting diversified strategies in genetic improvement programs. The present study aimed to characterize the morphology of pollen grains and seeds, and to infer the 2C DNA content using flow cytometry in species of the genus Passiflora with ornamental potential. For the morphological characterization of pollen grains and seeds, 11 and 12 descriptors were used, respectively. The data obtained were analyzed using ANOVA and grouped according to the Scott-Knott method. To study genetic diversity, the Mahalanobis distance matrix, and the UPGMA agglomerative method were used. For the morphological characterization of pollen and seeds, the results indicated significant differences across all descriptors. Four descriptors were particularly remarkably divergent: colpus width, equatorial axis, polar axis length, and the number of ornaments on the seeds. The species were grouped into three clusters in the dendrogram using the clustering method. 2C DNA content values demonstrated high interspecific variability, possibly due to chromosomal number and size. These results enabled the detection of genetic diversity, the significance of the biological trait values, and a better knowledge of interspecific gene interactions, all of which aid the selection of ornamental parent plants.

The species Passiflora alata, P. cincinnata, and P. edulis have great economic value due to the use of their fruits for human consumption. In this study, we compared the repetitive genome fractions of these three species. The compositions of the repetitive DNA of these three species’ genomes were analyzed using clustering and identification of the repetitive sequences with RepeatExplorer. It was found that repetitive DNA content represents 74.70%, 66.86%, and 62.24% of the genome of P. alata, P. edulis, and P. cincinnata, respectively. LTR Ty3/Gypsy retrotransposons represent the highest genome proportions in P. alata and P. edulis, while Ty1/Copia comprises the largest proportion of P. cincinnata genome. Chromosomal mapping by Fluorescent In Situ Hybridization (FISH) showed that LTR retrotransposons have a dispersed distribution along chromosomes. The subtelomeric region of chromosomes is where 145 bp satellite DNA is located, suggesting that these elements may play important roles in genome structure and organization in these species. In this work, we obtained the first global characterization of the composition of repetitive DNA in Passiflora, showing that an increase in genome size is related to an increase in repetitive DNA, which represents an important evolutionary route for these species.

Cacao fruits are agronomically important and show wide variability for several morphological descriptors. The present study aimed to characterize the genetic distance of 51 genotypes of Theobroma cacao L. in the cocoa-producing region of Southern Bahia (Brazil) based on morpho-agronomic descriptors. The inference of genetic similarity was performed from the phenotypic data derived simultaneously from qualitative and quantitative variables, using the Ward-MLM procedure (Modified Location Model) with the SAS^® software. The distance matrix was obtained using the Gower logarithmic function. For this, 28 descriptors were evaluated, five qualitative and 23 quantitative. Furthermore, using the likelihood function procedure, the optimal number of groups was five indicating wide variability. Of 23 quantitative descriptors evaluated by fruits and leaves, 95% showed significant differences. The exception was seed width. Groups 1 and 5 were the most distant, while groups 2, 3, and 4 were closest to each other. The greatest difference between increments was 35.32 for the fifth group. The analysis of the first two canonical axes revealed that both represented 81.88% of the variation, with CAN1 and CAN2 responsible for 53.66% and 28.22% of the variation. The most promising genotypes for breeding programs belong to group 5 due to their superior performance for almost all characteristics analyzed.

Black pod disease, caused by Phytophthora spp., is one of the main diseases that attack cocoa plantations. This study validated, by association mapping, 29 SSR molecular markers flanking to QTL (Quantitative Trait Loci) associated with Phytophthora palmivora Butler (Butler) (PP) resistance, in three local ancient varieties of the Bahia (Comum, Pará, and Maranhão), varieties that have a high potential in the production of gourmet chocolate. Four SSR loci associated with resistance to PP were detected, two on chromosome 8, explaining 7.43% and 3.72% of the Phenotypic Variation (%PV), one on chromosome 2 explaining 2.71%PV and one on chromosome 3 explaining 1.93%PV. A functional domains-based annotation was carried out, in two Theobroma cacao (CRIOLLO and MATINA) reference genomes, of 20 QTL regions associated with cocoa resistance to the pathogen. It was identified 164 (genome CRIOLLO) and 160 (genome MATINA) candidate genes, hypothetically involved in the recognition and activation of responses in the interaction with the pathogen. Genomic regions rich in genes with Coiled-coils (CC), nucleotide binding sites (NBS) and Leucine-rich repeat (LRR) domains were identified on chromosomes 1, 3, 6, 8, and 10, likewise, regions rich in Receptor-like Kinase domain (RLK) and Ginkbilobin2 (GNK2) domains were identified in chromosomes 4 and 6.

O objetivo deste estudo foi otimizar e estabelecer um protocolo visando elevar a qualidade e quantidade do ácido desoxirribonucleico (DNA) extraído de folhas, em diferentes estágios de desenvolvimento e conservação, coletadas em plantas adultas e plantas jovens. Além disso, almejou-se padronizar a amplificação via reação de polimerase em cadeia (PCR) e selecionar os marcadores de inter sequência simples repetida (ISSR) de Elaeis guineensis (dendezeiro). O protocolo brometo de cetiltrimetilamônio (CTAB) modificado, devido à suplementação com betamercapto etanol (0,3%) e polivinilpirrolidone (PVP) (3%) no tampão de extração e CTAB 10% com 1,4 M de NaCl a 20 min de incubação, a 650C, resultou em melhorias qualitativas e quantitativas na extração do DNA, mas com variações entre amostras, provavelmente, devido às variações na degradação e estágio de desenvolvimento das folhas. Foram utilizados dois protocolos de PCR (I e II) para a amplificação do DNA, os quais diferiram principalmente com relação à presença de albumina de soro bovino (BSA) e concentração de primer. Não foi realizada a correlação entre amplificação via PCR e qualidade de DNA, obtidos de folhas danificadas ou sadias, mas se observou que a adição de BSA (0,075 mg/mL) e o aumento na concentração de primer (0,5 pcmol) (protocolo II) resultou em bandas mais intensas e distinguíveis, porém se ressalta que a qualidade do DNA foi essencial para uma boa amplificação, considerando-se todas as amostras. A amplificação do DNA com o protocolo II possibilitou a seleção de cinco primers: UBC 807, 810, 812, 834 e 848; os quais foram utilizados para a amplificação de13 famílias, compostas de uma planta parental e oito progênies cada.