Antônio Félix da Costa

Rhynchospora nervosa is a weed associated with infestations in economically important agricultural crops in several regions of Brazil. In this context, the present study aimed to perform phytochemical screening and evaluate the allelopathic effects of aqueous extracts from the aerial (AEAP) and underground (AEUP) parts of R. nervosa on the germination and initial development of cowpea (cultivar IPA 206). The presence of phenols, flavonoids, terpenes, and saponins was observed in AEAP, while only phenols were identified in AEUP. Furthermore, fractionation of the crude extract suggested the possible presence of kaempferol, a flavonoid, detected in the ethyl acetate fraction of the aerial parts of R. nervosa. At the highest concentration (100%), AEAP and AEUP inhibited cowpea seed germination by only 11.67% and 6.67%, respectively, when compared to the control treatment (0% inhibition). Furthermore, no significant differences were observed in the fresh and dry masses of seedlings exposed to the different concentrations of the extracts. Hypocotyl length increased significantly (above 8.25 cm) at all concentrations tested compared to the control (6.40 cm). The rootlets also showed significant growth (above 6.60 cm) compared to the control (4.43 cm). Based on these results, further investigation into the potential application of aqueous extracts of R. nervosa as biostimulants for cowpea, under both greenhouse and field conditions, is warranted.

The pod fly Melanagromyza vignalis Spencer (Diptera: Agromyzidae) has posed a major constraint to cowpea cultivation because it damages pods and seeds, thus representing a pest of significant economic importance. This study aimed to clarify the identity of the pod fly responsible for damage to cowpea crops in the North and Northeast regions of Brazil. Specimens collected from cowpea production areas in the states of Pará, Paraíba, and Pernambuco were identified as M. vignalis through morphological and molecular analyses. The species is native to the African continent, and this report constitutes the first record for South America. The larvae damage developing grains, rendering them unfit for consumption. Species identification represents the first step toward implementing appropriate control strategies for this pest in Brazil.

O cultivo da palma no semiárido brasileiro cresce devido à sua alta produtividade, resistência climática e adaptação a ambientes áridos. Apesar de estudos sobre sua produtividade, há pouca investigação sobre o impacto das características morfológicas na diversidade fenotípica e desempenho agronômico da mesma. A variação entre gêneros e espécies ressalta a importância da caracterização fenotípica e catalogação do germoplasma para o melhoramento genético. Este estudo caracterizou morfologicamente acessos de palma forrageira dos gêneros Opuntia e Nopalea do Banco Ativo de Germoplasma do IPA. O experimento foi realizado em Arcoverde-PE, avaliando 80 acessos conforme descritores da cultura. A análise comparativa revelou significativa diversidade fenotípica, com variações morfológicas interligadas impactando a dissimilaridade entre acessos. Para Nopalea, a Análise de Componentes Principais (PCA) explicou 72% da variabilidade dos dados, separando os acessos em três grupos distintos. Enquanto Opuntia, a PCA explicou 40,1% da variabilidade, formando oito grupos e evidenciando maior diversidade. Os acessos de Nopalea apresentaram estrutura fenotípica mais homogênea, em contraste Opuntia mostrou maior variação. Desta forma, as 15 características morfológicas utilizadas foram eficazes na discriminação dos acessos, demonstrando a relação entre variabilidade morfológica e estrutura genética. A análise de caracteres quantitativos revelou padrões fenotípicos associados a grupos genéticos e adaptação local, contribuindo para futuras estratégias de melhoramento genético da palma forrageira.

Cowpea (Vigna unguiculata) is a crop of significant socioeconomic importance, particularly in the semi-arid regions of Africa and America. However, its productivity has been adversely affected by viral diseases, including the cowpea aphid-borne mosaic virus (CABMV), a single-stranded RNA virus. It is known that the VPg protein interacts with the host’s translation initiation factor (eIF4E), promoting viral replication. This study aimed to investigate the relationship between mutations in the cowpea eIF4E gene and resistance to CABMV. Twenty-seven cultivars were screened by PCR and bioassays for presence/absence of mutations associated with resistance or susceptibility to Potyviruses. Of the cultivars with mutations previously associated with susceptibility, 88.24% exhibited viral symptoms, while 62.5% associated with resistance remained asymptomatic. The in silico analyses revealed that non-synonymous mutations (Pro68Arg, Gly109Arg) alter the structure of the eIF4E protein, reducing its affinity to VPg. Molecular dynamics simulations also pointed to an enhanced structural stability of eIF4E in resistant cultivars and reinforced, for the first time, key mutations and the functional role of the eIF4E gene in resistance to CABMV in cowpea. Our results offer valuable insights for virus disease management and for genetic improvement programs for this important crop.

The genus Vigna Savi (Leguminosae Juss.) comprises approximately 150 species, classified into five subgenera, most of which exhibit a diploid chromosome number of 2n = 22. However, the wild species Vigna lasiocarpa (Benth) Verdc. (V. subg. Lasiospron) is notable for its dysploid chromosome number of 2n = 20. This study aimed to elucidate the chromosomal events involved in the karyotype evolution of V. lasiocarpa (Vla). We used oligopainting probes from chromosomes 1, 2, 3, and 5 of Phaseolus vulgaris L. and two barcode probes from the genome of V. unguiculata (L.) Walp. Additionally, bacterial artificial chromosomes (BACs) from V. unguiculata and P. vulgaris, along with a telomeric probe from Arabidopsis thaliana (L.) Heynh., were hybridized to V. lasiocarpa metaphase chromosomes to characterize Vla3, Vla7/5, and Vla9. Our findings revealed conserved oligo-FISH patterns on chromosomes 2, 6, 8, 10, and 11 between V. unguiculata and V. lasiocarpa. Paracentric and pericentric inversions were identified for Vla3 and Vla9, respectively. Our integrative approach revealed that the dysploid chromosome originated from an “end-to-end fusion” of homoeologous chromosomes 5 and 7. This is the first report on the chromosomal mechanisms underlying descending dysploidy in Vigna, providing new insights into the evolutionary dynamics of the genus.

Energy demand has become a global bottleneck, and the search for alternative sources is intensifying worldwide. In this context, elephant grass emerges as an excellent alternative due to its high dry matter production capacity coupled with beneficial biomass quality, high fiber content, high C/N ratio, and high calorific value. Given the significance of forage in bioenergy production, this study aimed to estimate the adaptability and stability parameters through mixed models (restricted maximum likelihood/best linear unbiased prediction [REML/BLUP) and repeatability for the selection of the best elephant grass genotypes. Seventy‐three genotypes were evaluated in a randomized block design with three replicates from the Active Elephant Grass Germplasm Bank of the State University of Northern Rio de Janeiro, located in Campos dos Goytacazes, RJ, Brazil. Dry matter yield, number of tillers, plant height, and stem diameter were evaluated. The statistical analysis was based on mixed models using REML/BLUP. The repeatability values obtained demonstrated that the genotypes' performance remained consistent across all measurements, with eight measurements necessary to ensure the selection of the best genotypes. The genotypes King Grass, Taiwan A‐46, Pasto Panamá, Três Rios, and Guaçu/I.Z.2 were the most productive, adaptable, and stable, displaying potential for cultivation in the northern region of Rio de Janeiro and for use in breeding programs.

Histone methyltransferases (SDGs) and demethylases (JMJs) are well-established regulators of transcriptional responses in plants under adverse conditions. This study characterized SDG and JMJ enzymes in the cowpea (Vigna unguiculata) genome and analyzed their expression patterns under various stress conditions, including root dehydration and mechanical injury followed by CABMV or CPSMV inoculation. A total of 47 VuSDG genes were identified in the cowpea genome and classified into seven distinct classes: I, II, III, IV, V, VI, and VII. Additionally, 26 VuJMJ-coding genes were identified and categorized into their respective groups: Jmj-only, JMJD6, KDM3, KDM5, and KDM4. Analysis of gene expansion mechanisms for the studied loci revealed a predominance of dispersed duplication and WGD/segmental duplication events, with Ka/Ks ratios indicating that all WGD/segmental duplications are under purifying selection. Furthermore, a high degree of conservation was observed for these loci across species, with legumes displaying the highest conservation rates. Cis-Regulatory Element analysis of VuSDG and VuJMJ gene promoters revealed associations with Dof-type and bZIP transcription factors, both of which are known to play roles in plant stress responses and developmental processes. Differential expression patterns were observed for VuSDG and VuJMJ genes under the studied stress conditions, with the highest number of upregulated transcripts detected during the root dehydration assay. Our expression data suggest that as the referred stress persists, the tolerant cowpea accession decreases methylation activity on target histones and shifts towards enhanced demethylation. This dynamic balance between histone methylation and demethylation may regulate the expression of genes linked to dehydration tolerance. During the mechanical injury and viral inoculation assays, VuSDG and VuJMJ transcripts were upregulated exclusively within 60 min after the initial mechanical injury combined with CABMV or CPSMV inoculation, indicating an early role for these enzymes in the plant’s defense response to pathogen exposure. The current study presents a detailed analysis of histone modifiers in cowpea and indicates their role as important epigenetic regulators modulating stress tolerance.

The common bean (Phaseolus vulgaris L.) is crucial for human nutrition, providing proteins and essential nutrients to millions of families globally. This crop faces significant challenges from diseases caused by phytopathogenic fungi like Macrophomina phaseolina and Fusarium spp.. Trichoderma sp. is known for its ability to produce secondary metabolites with antagonistic properties against various phytopathogens. This study aimed to evaluate the antagonistic potential of volatile and non-volatile metabolites produced by Trichoderma in inhibiting the mycelial growth of Macrophomina phaseolina, Fusarium triseptatum, Fusarium annulatum, and Fusarium fabacearum. Tests involved three Trichoderma species (T. asperelloides, T. asperellum, and T. afroharzianum). Volatile metabolites were tested using the double plate method, while non-volatile metabolites were assessed by incorporating Trichoderma filtrate into 25% Potato Dextrose Agar (PDA), with the pathogen placed in the Petri dish center. Results demonstrated that both types of metabolites effectively controlled phytopathogens, with T. asperelloides (URM8945 and URM8946) showing notable inhibition of M. phaseolina isolates, and T. asperellum (URM8998) and T. afroharzianum (URM8938) exhibiting activity against F. annulatum. Volatile compounds were generally more effective against Fusarium spp. isolates compared to non-volatile metabolites. Therefore, metabolites from these Trichoderma species should be considered for sustainable disease management in common bean crops.

Cowpea (Vigna unguiculata (L.) Walp.) is an important legume cultivated mainly in regions with limited water availability across the African and American continents. Its productivity is significantly affected by environmental stresses. Thaumatin-like proteins (TLPs), which belong to the PR-5 (pathogenesis-related 5) protein family, are known to be responsive to both biotic and abiotic stresses. However, their role remains controversial, with some TLPs associated with plant defense (particularly against fungal infections) and others associated with abiotic stresses response. In this study, we evaluated the structural diversity and gene expression of TLPs in cowpea (VuTLPs) under different stress conditions, including biotic [mechanical injury followed by inoculation with Cowpea Aphid-borne Mosaic Virus (CABMV) or Cowpea Severe Mosaic Virus (CPSMV)] and abiotic (root dehydration). Genomic anchoring of VuTLPs revealed 34 loci encoding these proteins. Neighbor- joining analysis clustered the VuTLPs into three distinct groups. We identified 15 segmental duplication and 6 tandem duplication gene pairs, with the majority of VuTLP genes found to be under purifying selection. Promoter analysis associated VuTLPs with bHLH, Dof-type, and MYB- related transcription factors, supporting their diverse roles. Diversity in VuTLP function was also observed in their expression profiles under the studied stress conditions. Gene expression data showed that most VuTLPs are recruited within the first minutes after biotic stress imposition. For the root dehydration assay, the most transcripts were up-regulated 150 min post-stress. Moreover, the gene expression data suggested that VuTLPs exhibit functional specialization depending on the stress condition, highlighting their diverse roles and biotechnological potential.

O Brasil é um dos maiores produtores e consumidores de feijão, destacando-se pela importância dessa cultura na segurança alimentar e na economia agrícola do país. O feijão comum tem origem na Mesoamérica e América do Sul, regiões com alta diversidade genética essencial para o melhoramento genético. A conservação do germoplasma dessas áreas é crucial para evitar a erosão genética e preservar alelos importantes. A caracterização morfológica e fisiológica do feijão comum é fundamental no processo de melhoramento, permitindo a identificação de características desejáveis, como tamanho, forma dos grãos, e resistência a condições adversas. Essas análises são essenciais para desenvolver variedades que combinem alta produtividade, resistência a doenças e adaptação a diferentes ambientes de cultivo. O sucesso do melhoramento genético depende da colaboração entre instituições públicas e privadas, que juntas garantem a conservação da diversidade genética e o avanço contínuo das cultivares. Esse processo é vital para a segurança alimentar e a sustentabilidade agrícola no Brasil, possibilitando a criação de cultivares mais produtivas, adaptadas e resilientes, contribuindo para uma agricultura eficiente e duradoura.