The Stilbene Synthase Family in Arachis: A Genome-Wide Study and Functional Characterization in Response to Stress.

Peanut (Arachis hypogaea) and its wild relatives are among the few species that naturally synthesize resveratrol, a well-known stilbenoid phytoalexin that plays a crucial role in plant defense against biotic and abiotic stresses. Resveratrol has received considerable attention due to its health benefits, such as preventing and treating various human diseases and disorders. Chalcone (CHS) and Stilbene (STS) Synthases are plant-specific type III Polyketide Synthases (PKSs) that share the same substrates and are key branch enzymes in the biosynthesis of flavonoids and stilbenoids, respectively. Although resveratrol accumulation in response to external stimulus has been described in peanut, there are no comprehensive studies of the CHS and STS gene families in the genus Arachis. In the present study, we identified and characterized 6 CHS and 46 STS genes in the tetraploid peanut and an average of 4 CHS and 22 STS genes in three diploid wild species (Arachis duranensis, Arachis ipaënsis and Arachis stenosperma). The CHS and STS gene and protein structures, chromosomal distributions, phylogenetic relationships, conserved amino acid domains, and cis-acting elements in the promoter regions were described for all Arachis species studied. Based on gene expression patterns of wild A. stenosperma STS genes in response to different biotic and abiotic stresses, we selected the candidate AsSTS4 gene, which is strongly induced by ultraviolet (UV) light exposure, for further functional investigation. The AsSTS4 overexpression in peanut hairy roots significantly reduced (47%) root-knot nematode infection, confirming that stilbene synthesis activation in transgenic plants can increase resistance to pathogens. These findings contribute to understanding the role of resveratrol in stress responses in Arachis species and provide the basis for genetic engineering for improved production of valuable secondary metabolites in plants.

Transcriptome Responses of Wild Arachis to UV-C Exposure Reveal Genes Involved in General Plant Defense and Priming.

Stress priming is an important strategy for enhancing plant defense capacity to deal with environmental challenges and involves reprogrammed transcriptional responses. Although ultraviolet (UV) light exposure is a widely adopted approach to elicit stress memory and tolerance in plants, the molecular mechanisms underlying UV-mediated plant priming tolerance are not fully understood. Here, we investigated the changes in the global transcriptome profile of wild Arachis stenosperma leaves in response to UV-C exposure. A total of 5751 differentially expressed genes (DEGs) were identified, with the majority associated with cell signaling, protein dynamics, hormonal and transcriptional regulation, and secondary metabolic pathways. The expression profiles of DEGs known as indicators of priming state, such as transcription factors, transcriptional regulators and protein kinases, were further characterized. A meta-analysis, followed by qRT-PCR validation, identified 18 metaDEGs as being commonly regulated in response to UV and other primary stresses. These genes are involved in secondary metabolism, basal immunity, cell wall structure and integrity, and may constitute important players in the general defense processes and establishment of a priming state in A. stenosperma. Our findings contribute to a better understanding of transcriptional dynamics involved in wild Arachis adaptation to stressful conditions of their natural habitats.

Population genetic relationships between Casearia sylvestris (Salicaceae) varieties occurring sympatrically and allopatrically in different ecosystems in south-east Brazil.

BACKGROUND AND AIMS: Species delimitation can be problematic, and recently diverged taxa are sometimes viewed as the extremes of a species' continuum in response to environmental conditions. Using population genetic approaches, this study assessed the relationship between two Casearia sylvestris (Salicaceae) varieties, which occur sympatrically and allopatrically in the landscape of south-east Brazil, where intermediate types are also found. METHODS: In total, 376 individuals from nine populations in four different ecosystems were sampled, and nine microsatellite markers were used to assess the relative effects of the ecosystems and varieties on the distribution of genetic diversity among populations of this species. KEY RESULTS: As a by-product of this study, several PCR products with more than two alleles were observed. The possibility that extra bands represent non-specific amplification or PCR artefacts was discarded by sequencing a sample of these bands. We suggest that (partial) genome duplication in C. sylvestris most probably explains this phenomenon, which may be a key factor in the differentiation of the two taxa, as it was markedly more frequent in one of the varieties. AMOVA indicated that approx. 22 % of the total genetic diversity was found between the two varieties. Bayesian analysis identified varieties and ecosystems as evolutionary units, rather than the individual populations sampled. CONCLUSIONS: The results are in agreement with field observations and support the recognition of two varieties, as well as documenting the occurrence of hybridization between them.

Chemical composition and biological activities of Arachis species.

Arachis hypogaea , known as the peanut, is native to South America. Peanut contains several active components including flavonoids, phenolic acids, phytosterols, alkaloids, and stilbenes. Some therapeutic effects have been reported for peanut seed extracts, such as antioxidative, antibacterial, antifungal, and anti-inflammatory activities. This paper aims to give an overview of the chemical composition, focusing on secondary metabolites, and of the biological activity of A. hypogaea, to stimulate new studies about species of the Arachis genus.

Transferability and use of microsatellite markers for the genetic analysis of the germplasm of some Arachis section species of the genus Arachis

The Arachis section is the most important of the nine sections of the genus Arachis because it includes the cultivated peanut, Arachis hypogaea. The genetic improvement of A. hypogaea using wild relatives is at an early stage of development in spite of their potential as sources of genes, including those for disease and pests resistance, that are not found in the A. hypogaea primary gene pool. Section Arachis species germplasm has been collected and maintained in gene banks and its use and effective conservation depends on our knowledge of the genetic variability contained in this material. Microsatellites are routinely used for the analysis of genetic variability because they are highly polymorphic and codominant. The objective of this study was to evaluate the transferability of microsatellite primers and the assay of genetic variability between and within the germplasm of some species of the Arachis section. Fourteen microsatellite loci developed for three different species of Arachis were analyzed and 11 (78 percent) were found to be polymorphic. All loci had transferability to all the species analyzed. The polymorphic loci were very informative, with expected heterozygosity per locus ranging from 0.70 to 0.94. In general, the germplasm analyzed showed wide genetic variation.

Acid phosphatase polymorphism within and among populations of Cauliflower (Brassica oleracea var botrytis)

Eighty-one lines of cauliflower (Brassica oleracea var. botrytis) from 12 populations used to produce commercial hybrids in Brazil were screened for polymorphism in the acid phosphatase system, in order to evaluate the usefulness of this marker for the determination of the parental contamination level in hybrid seeds. Little polymorphism was detected in the examined lines, but the system appeared to be very useful for hybrid identification, since the only condition required was polymorphism between the two parental lines. If the analyzed lines were used for hybrid production, 8.4 percent and 12.3 percent of the possible crosses would result in hybrids which can be positively identified using the APS-1 and B1 loci, respectively. If only one plant of each homozygous type (SS or FF) was analyzed in each population, 41 percent and 50 percent of the possible crosses would result in hybrids which can be positively identified using the APS-1 and B1 loci, respectively

Genetic characterization of isolates of the Basidiomycete Agaricus Blazei by rapd

The genetic divergence of five isolates of Agaricus blazei was determined based on RAPD data. Results indicate that there is little genetic variability among the commercialized strains and that RAPD is a feasible and low cost technique that can be used to characterize this fungus.

Análise cromossômica e molecular do javali europeu Sus scrofa scrofa e do suíno doméstico Sus scrofa domesticus / Cytogenetic and molecular analysis of a european wild boar Sus scrofa scrofa and domestic swine Sus scrofa domesticus

A presente investigação teve como objetivos: analisar animais presentes em diferentes criações de javalis no estado de São Paulo, com o intuito de auxiliar a identificação de javalis "puros" assim como javalis híbridos provenientes do cruzamento com o suíno doméstico, para tanto foram utilizadas avaliação do fenótipo dos animais, análises citogenéticas e da técnica molecular de RAPD (Random Amplified Polymorphic DNA).O estudo do número de cromossomos nas células diplóides em 104 animais destinados a análise citogenética e fenotípica, revelou polimorfismo de 2n=36, 37 e 38 cromossomos. Por meio da técnica de bandamento GTG foi possível identificação da translocação Robertsoniana entre os cromossomos 15 e 17 como responsável por esse polimorfismo. Todavia, somente com a análise citogenética isolada, não foi possível determinar se a origem desse polimorfismo é decorrente das hibridações com o suíno doméstico ou se são características inerentes ao javali. Contudo, quando associado a análise citogenética com as características fenotípicas, foi possível identificar a existência de hibridações. A análise citogenética nos animais submetidos a técnica de RAPD, revelou 2n=36 cromossomos nos 16 javalis assim como 2n=38 cromossomos nos 11 suínos e, por meio dessa técnica, foram possíveis agrupamentos, separando o suíno doméstico, javali e um possível híbrido revelando-se uma técnica com potencial no auxílio da identificação de híbridos