Alternative substrates for conidiogenesis of the entomopathogenic fungus Beauveria bassiana (Bals) Vuillemin (Deuteromycotina: Hyphomycetes) / Substratos alternativos para conidiogênese do fungo entomopatogênico Beauveria bassiana (Bals) Vuillemin (Deuteromycotina: Hyphomycetes)

Abstract Beauveria bassiana is a promising fungus for the biological control of insect pests. The growing costs of conidia production have raised the need to ascertain the efficiency of some low cost substrates. The aim of this study was to analyze the potential use of different raw substrates without nutritional supplement for B. bassiana conidiogenesis. Growth and sporulation were evaluated using 30 g of substrate and 0.3 μL of a conidia suspension (1 x 106 conidia/mL). After 10 days of incubation (70 ± 10% humidity and temperature (T) = 29 ± 1 °C), rice (2.00 x 106 conidia/g substrate), algaroba (2.36 x 106 conidia/g), malt A (1.22 x 106 conidia/g) and malt B (1.75 x 106 conidia/g) showed the highest levels of conidia production. The resulting conidia showed insecticidal activity higher than 80% on coconut termites. These new raw substrates may represent viable alternatives for the production of entomopathogenic fungi for use in the biological control of various insect pests.

Resumo Beauveria bassiana é um fungo promissor no controle biológico de insetos-praga. As crescentes despesas na produção de conídios levantam a necessidade de averiguar a eficiência de alguns substratos de baixo custo. O objetivo deste trabalho foi analisar o potencial de utilização de diferentes substratos brutos para a conidiogênese de B. bassiana. O crescimento e esporulação foram realizados utilizando 30 g do substrato e 0,3 µL da suspensão de conídios (1 x 106 conídios/mL). Após 10 dias de incubação (umidade 70 ± 10% e temperatura T = 29 ± 1° C), o arroz (2,00 x 106 conídios/g de substrato), algaroba (2,36 x 106 conídios/g), malte A (1,22 x 106 conídios/g) e B (1,75 x 106 conídios/g), apresentaram maior produção de conídios. Os conídios produzidos mostraram atividade inseticida sobre o cupim do coqueiro acima de 80% de mortalidade. Estes novos substratos brutos podem representar uma alternativa viável para produção de fungos entomopatogênicos para uso no controle biológico de vários insetos praga.

Alternative substrates for conidiogenesis of the entomopathogenic fungus Beauveria bassiana (Bals) Vuillemin (Deuteromycotina: Hyphomycetes).

Beauveria bassiana is a promising fungus for the biological control of insect pests. The growing costs of conidia production have raised the need to ascertain the efficiency of some low cost substrates. The aim of this study was to analyze the potential use of different raw substrates without nutritional supplement for B. bassiana conidiogenesis. Growth and sporulation were evaluated using 30 g of substrate and 0.3 µL of a conidia suspension (1 x 106 conidia/mL). After 10 days of incubation (70 ± 10% humidity and temperature (T) = 29 ± 1 °C), rice (2.00 x 106 conidia/g substrate), algaroba (2.36 x 106 conidia/g), malt A (1.22 x 106 conidia/g) and malt B (1.75 x 106 conidia/g) showed the highest levels of conidia production. The resulting conidia showed insecticidal activity higher than 80% on coconut termites. These new raw substrates may represent viable alternatives for the production of entomopathogenic fungi for use in the biological control of various insect pests.

Alternative substrates for conidiogenesis of the entomopathogenic fungus Beauveria bassiana (Bals) Vuillemin (Deuteromycotina: Hyphomycetes)

Abstract Beauveria bassiana is a promising fungus for the biological control of insect pests. The growing costs of conidia production have raised the need to ascertain the efficiency of some low cost substrates. The aim of this study was to analyze the potential use of different raw substrates without nutritional supplement for B. bassiana conidiogenesis. Growth and sporulation were evaluated using 30 g of substrate and 0.3 L of a conidia suspension (1 x 106 conidia/mL). After 10 days of incubation (70 ± 10% humidity and temperature (T) = 29 ± 1 °C), rice (2.00 x 106 conidia/g substrate), algaroba (2.36 x 106 conidia/g), malt A (1.22 x 106 conidia/g) and malt B (1.75 x 106 conidia/g) showed the highest levels of conidia production. The resulting conidia showed insecticidal activity higher than 80% on coconut termites. These new raw substrates may represent viable alternatives for the production of entomopathogenic fungi for use in the biological control of various insect pests.

Resumo Beauveria bassiana é um fungo promissor no controle biológico de insetos-praga. As crescentes despesas na produção de conídios levantam a necessidade de averiguar a eficiência de alguns substratos de baixo custo. O objetivo deste trabalho foi analisar o potencial de utilização de diferentes substratos brutos para a conidiogênese de B. bassiana. O crescimento e esporulação foram realizados utilizando 30 g do substrato e 0,3 µL da suspensão de conídios (1 x 106 conídios/mL). Após 10 dias de incubação (umidade 70 ± 10% e temperatura T = 29 ± 1° C), o arroz (2,00 x 106 conídios/g de substrato), algaroba (2,36 x 106 conídios/g), malte A (1,22 x 106 conídios/g) e B (1,75 x 106 conídios/g), apresentaram maior produção de conídios. Os conídios produzidos mostraram atividade inseticida sobre o cupim do coqueiro acima de 80% de mortalidade. Estes novos substratos brutos podem representar uma alternativa viável para produção de fungos entomopatogênicos para uso no controle biológico de vários insetos praga.

Genetic diversity of the forage peanut in the Jequitinhonha, São Francisco, and Paranã River valleys of Brazil.

Arachis pintoi and A. repens are legumes with a high forage value that are used to feed ruminants in consortium systems. Not only do they increase the persistence and quality of pastures, they are also used for ornamental and green cover. The objective of this study was to analyze microsatellite markers in order to access the genetic diversity of 65 forage peanut germplasm accessions in the section Caulorrhizae of the genus Arachis in the Jequitinhonha, São Francisco and Paranã River valleys of Brazil. Fifty-seven accessions of A. pintoi and eight of A. repens were analyzed using 17 microsatellites, and the observed heterozygosity (HO), expected heterozygosity (HE), number of alleles per locus, discriminatory power, and polymorphism information content were all estimated. Ten loci (58.8%) were polymorphic, and 125 alleles were found in total. The HE ranged from 0.30 to 0.94, and HO values ranged from 0.03 to 0.88. By using Bayesian analysis, the accessions were genetically differentiated into three gene pools. Neither the unweighted pair group method with arithmetic mean nor a neighbor-joining analysis clustered samples into species, origin, or collection area. These results reveal a very weak genetic structure that does not form defined clusters, and that there is a high degree of similarity between the two species.

Genetic diversity of Metrodorea nigra (Rutaceae) from a small forest remnant in Brazil assessed with microsatellite markers.

Metrodorea nigra (Rutaceae) is an endemic Brazilian tree of great ecological importance, frequently found in the submontane regions of ombrophilous dense and semideciduous forests. This tree is useful for reforesting degraded areas and the wood can be employed in construction. We developed 12 microsatellite markers from a genomic library enriched for GA/CA repeats, for this species. Polymorphisms were assessed in 40 trees of a highly fragmented population found in Cravinhos, State of São Paulo, in southeastern Brazil. Among the 12 loci, 8 were polymorphic and only one had fixed alleles in this population. The number of alleles per locus and expected heterozygosity ranged from 2 to 11 and from 0.190 to 0.889, respectively. These results revealed moderate levels of genetic variation in M. nigra population when compared to other tropical species. Additionally, transferability of the 12 primers was tested in seven other Brazilian Rutaceae tree species (endemics: M. stipularis, Galipea jasminiflora, Esenbeckia leiocarpa and non-endemics: E. febrifuga, E. grandiflora, Balfourodendron riedelianum, Zanthoxylum riedelianum). Transferability ranged among species, but at least 8 loci (~67%) amplified in M. stipularis, demonstrating a high potential for transferring microsatellite markers between species of the same genus in the Rutaceae family.

Pathogenicity for onion and genetic diversity of isolates of the pathogenic fungus Colletotrichum gloeosporioides (Phyllachoraceae) from the State of Pernambuco, Brazil.

Onion anthracnose, caused by Colletotrichum gloeosporioides, is one of the main diseases of onions in the State of Pernambuco. We examined the pathogenicity of 15 C. gloeosporioides strains and analyzed their genetic variability using RAPDs and internal transcribed spacers (ITS) of the rDNA region. Ten of the strains were obtained from substrates and hosts other than onion, including chayote (Sechium edule), guava (Psidium guajava), pomegranate (Punica granatum), water from the Capibaribe River, maracock (Passiflora sp), coconut (Cocus nucifera), surinam cherry (Eugenia uniflora), and marine soil; five isolates came from onions collected from four different regions of the State of Pernambuco and one region of the State of Amazonas. Pathogenicity tests were carried out using onion leaves and bulbs. All strains were capable of causing disease in leaves, causing a variable degree of lesions on the leaves; four strains caused the most severe damage. In the onion bulb tests, only three of the above strains caused lesions. Seven primers of arbitrary sequences were used in the RAPD analysis, generating polymorphic bands that allowed the separation of the strains into three distinct groups. The amplification products generated with the primers ITS1 and ITS4 also showed polymorphism when digested with three restriction enzymes, DraI, HaeIII and MspI. Only the latter two demonstrated genetic variations among the strains. These two types of molecular markers were able to differentiate the strain from the State of Amazonas from those of the State of Pernambuco. However, there was no relationship between groups of strains, based on molecular markers, and degree of pathogenicity for onion leaves and bulbs.

Genetic diversity and population structure analysis of the tropical pasture grass Brachiaria humidicola based on microsatellites, cytogenetics, morphological traits, and geographical origin.

Brachiaria humidicola (Rendle) Schweick. is a warm-season grass commonly used as forage in the tropics. Accessions of this species were collected in eastern Africa and massively introduced into South America in the 1980s. Several of these accessions form a germplasm collection at the Brazilian Agricultural Research Corporation. However, apomixis, ploidy, and limited knowledge of the genetic basis of this germplasm collection have constrained breeding activities. The objectives of this work were to identify genetic variability in the Brazilian B. humidicola germplasm collection using microsatellite markers and to compare the results with information on the following: (1) collection sites of the accessions; (2) reproductive mode and ploidy levels; and (3) genetic diversity revealed by morphological traits. The evaluated germplasm population is highly structured into four major groups. The sole sexual accession did not group with any of the clusters. Genetic dissimilarities did not correlate with either geographic distances or genetic distances inferred from morphological descriptors. Additionally, the genetic structure identified in this collection did not correspond to differences in ploidy level. Alleles exclusive to either sexual or apomictic accessions were identified, suggesting that further evaluation of the association of these loci with apospory should be carried out.

Isolation and characterization of microsatellite loci in Pitcairnia albiflos (Bromeliaceae), an endemic bromeliad from the Atlantic Rainforest, and cross-amplification in other species.

Eight microsatellite markers were isolated from Pitcairnia albiflos, an endangered endemic bromeliad species restricted to 'inselberg' rock outcrops in the state of Rio de Janeiro, Brazil. The number of alleles observed for each locus ranged from two to 12. Average observed and expected heterozygosities were 0.408 and 0.663, respectively. The cross-amplification test in 16 taxa suggests that the markers will be useful in numerous related bromeliad species. The loci will be used to study genetic structure and reproductive biology in fragmented inselberg populations and the origin and maintenance of barriers to gene flow between sympatric Pitcairnia species.