Harllen Sandro Alves Silva

Bioprospecting endophytic bacteria for biological control of coffee leaf rust

Suppression of plant diseases due to the action of endophytic microorganisms has been demonstrated in several pathosystems. Experiments under controlled conditions involving endophytic bacteria isolated from leaves and branches of Coffea arabica L and Coffea robusta L were conducted with the objective of evaluating the inhibition of germination of Hemileia vastatrix Berk. & Br., race II, urediniospores and the control of coffee leaf rust development in tests with leaf discs, detached leaves, and on potted seedling of cv. Mundo Novo. The endophytic bacterial isolates tested proved to be effective in inhibiting urediniospore germination and/or rust development, with values above 50%, although the results obtained in urediniospore germination tests were inferior to the treatment with fungicide propiconazole. Endophytic isolates TG4-Ia, TF2-IIc, TF9-Ia, TG11-IIa, and TF7-IIa, demonstrated better coffee leaf rust control in leaf discs, detached leaves, and coffee plant tests. The endophytic isolates TG4-Ia and TF9-Ia were identified as Bacillus lentimorbus Dutky and Bacillus cereus Frank. & Frank., respectively. Some endophytic bacterial isolates were effective in controlling the coffee leaf rust, although some increased the severity of the disease. Even though a relatively small number of endophytic bacteria were tested, promising results were obtained regarding the efficiency of coffee leaf rust biocontrol. These selected agents appears to be an alternative for future replacement of chemical fungicide.

Evidence that the biocontrol agent Bacillus cereus synthesizes protein that can elicit increased resistance of tomato leaves to Corynespora cassiicola

Isolate UFV-101 of Bacillus cereus was selected in previous studies for promoting growth inducing resistance in plants. In a previous study, supernatant from cultures of the microorganism in a liquid medium was found to induce resistance in tomato foliage against the pathogens Pseudomonas syringae pv. tomato, Xanthomonas vesicatoria, Alternaria solani and Corynespora cassiicola. In the present work the microorganism was grown in a minimal medium for 48 h and the cells precipitated for centrifugation. The supernatant was concentrated by lyophilization, dialyzed in a 12 kDa cut-off point membrane and fractioned in column containing Sephadex G25 balanced in PBS buffer. The fractions corresponding to a protein peak were applied to tomato seedlings. After four days leaflets were collected and inoculated with the pathogen. C. cassiicola. The numbers of lesions produced by the pathogen on leaflets exposed to the bacterial supernatant were similar to those exposed to acibenzolar-S-methyl but fewer than in those treated with water. It is concluded that the supernatant contained protein which induced resistance in the tomato leaves against C. cassiicola.

Antagonismo direto e biocontrole da podridão‑mole‑do‑tomateiro pelo uso de procariotas

O objetivo deste trabalho foi avaliar procariotas quanto ao potencial de antagonismo direto para o biocontrole da podridao-mole-do-tomateiro (Pectobacterium carotovorum subsp. carotovorum). Avaliaram-se 45 isolados bacterianos pelo teste de antibiose contra o patogeno. Foram feitos dois ensaios em que sementes de tomate (Lycopersicon esculentum Mill.) cv. Santa Clara foram infectadas com isolados antagonicos. As mudas foram transplantadas para solos infestados com suspensoes de propagulos P. carotovorum com OD540 de 0,45 e 0,65. Os antagonistas UFV-0005, UFV-043, UFV-BF112 e UFV-0006 foram eficientes em proteger plantas de tomateiro contra a podridao-mole.

Detecção de Pseudomonas viridiflava em sementes importadas de couve chinesa (Brassica rapa var. pekinensis)

ABSTRACT A natural occurrence of Pseudomonas viridiflava inchinese cabbage ( Brassica rapa var. pekinensis ) imported seedsfrom Japan is described. From the epidemiological point of Maciel, K.W.; Almeida, I.M.G.; Silva, H.S.A; Rodrigues, L.M.S.; Beriam, L.O.S. Detection of Pseudomonas viridiflava in imported chinesecabbage ( Brassica rapa var. pekinensis ) seeds. Summa Phytopathologica, v.36, n.1, p.83-84, 2010. Keywords: bacterial disease. Palavras-chave adicionais: cdoenca bacteriana RESUMO A ocorrencia de Pseudomonas viridiflava e descrita em sementesde couve chinesa ( Brassica rapa var. pekinensis ) importadas do Japao.Do ponto de vista epidemiologico, a deteccao dessa bacteria e deextrema importância. Embora ja existam, em nosso pais, relatos desse Maciel, K.W.; Almeida, I.M.G.; Silva, H.S.A; Rodrigues, L.M.S.; Beriam, L.O.S. Deteccao de Pseudomonas viridiflava em sementes importadasde couve chinesa ( Brassica rapa var. pekinensis ). Summa Phytopathologica, v.36, n.1, p.83-84, 2010.