Isolation and Characterization of Plant Growth-Promotion Diazotrophic Endophytic Bacteria Associated to Sugarcane (Saccharum officinarum L.) Grown in Paraíba, Brazil

Abstract: Sugarcane is an important Brazilian commodity, being usually cultivated in soils with low natural fertility. This study aimed to isolate diazotrophic endophytes from sugarcane tissues and evaluate the morphological and physiological characteristics of their colonies as well as their plant growth-promoting (PGP) traits in select diazotrophic endophytic bacteria. Fifty-six bacterial isolates were identified in the sugarcane tissues, and these isolates presented distinct morphological and physiological traits. A total of thirty-five bacterial isolates were biochemically evaluated. Overall, Bacillus was the dominant genus. Isolates of Methylobacterium spp. and Brevibacillus agri were present only in leaves, while Herbaspirillum seropedicae occurred only in stems. Except to IPA-CF45A, all isolates were nitrogenase positive. All endophytes exhibit production of indol 3-acetic acid. Over 50% of endophytes solubilize phosphate, release N-acyl homoserine lactones, and present the activity of 1-aminocyclopropane-1-carboxylic acid deaminase, catalase, lipase and protease. The network analysis showed that isolates belonged to Burkholderia, Herbaspirillum, and Methylobacterium interact with Bacillus. Bacterial endophytes exhibited distinct morphological, physiological, and PGP traits that are useful for sustainable agriculture, highlighting the isolates IPA-CC33, IPA-CF65, IPA-CC9 and IPA-CF27. Further studies on the effects of these diazotrophic endophytes and their potential for providing microbial inoculants for improving sugarcane fields will provide valuable information to maintain the sustainability and environment quality.

Inoculation of arbuscular mycorrhizal fungi as a strategy to improve annatto (Bixa orellana L. ) growth

This study aimed to assess the occurrence of arbuscular mycorrhizal fungi (AMF) in annatto (Bixa orellana L.) cultivars and their response to AMF inoculation using biometric parameters. The occurrence surveys were conducted in annatto fields in three municipalities from Pernambuco Forest Zone: Lagoa de Itaenga, Gloria de Goitá, and Vitoria de Santo Antão, and in four cultivars (Red Piave, Green Piave, Red Peruvian Paulista, and Green Peruvian Paulista). In a greenhouse, biometric parameters of annatto seedlings of Red Piave, Red Peruvian Paulista, Embrapa-36, and Embrapa-37 cultivars inoculated with AMF isolated from annatto fields. The Red Piave cultivar exhibited greater root colonization than the Green Peruvian Paulista in the Lagoa de Itaenga and Vitoria de Santo Antão municipalities. The cultivar Red Piave showed a more beneficial association with AMF in plants and soil than cultivar Green Peruvian Paulista did, in both Lagoa de Itaenga and Vitoria de Santo Antão. AMF inoculation was effective in promoting the growth of annatto plants, particularly those inoculants with S. heterogama and C. etunicatum.

Bacillus subtilis improves maize tolerance to salinity / Bacillus subtilis melhora a tolerância do milho a salinidade

ABSTRACT: The aim of this study was to evaluate the biochemical responses of maize, under saline stress, inoculated with Bacillus subtilis. Four levels of salinity were assessed: 0mM, 50mM, 100mM, and 200mM of sodium chloride (NaCl). Saline conditions influenced negatively maize growth. However, the inoculation of B. subtilis improved the plant growth at highest level of NaCl. Chlorophyll content decreased while proline increased in inoculated plants submitted to highest salt levels. Also, B. subtilis increased the relative water content in leaves. B. subtilis improves the plant growth under salinity and ameliorates the biochemical damages in maize.

RESUMO: O objetivo do estudo foi avaliar a resposta bioquímica do milho, sob stresse salino, inoculado com Bacillus subtilis. Quatro níveis de salinidade foram avaliados: 0mM, 50mM, 100mM e 200mM de cloreto de sódio (NaCl). Condições salinas influenciaram negativamente o crescimento do milho. Entretanto, a inoculação com B. subtilis melhorou o crescimento das plantas no maior nível de NaCl. O teor de clorofila decresceu enquanto que a prolina aumentou em plantas submetidas aos níveis salinos e inoculadas com B. subtilis. B. subtilis também aumentou o conteúdo de agua foliar. A inoculação com B. subtilis promove melhor crescimento das plantas sob salinidade e atenua os danos bioquímicos no milho.

Resposta da co-inoculação de bactérias promotoras de crescimento em plantas e Bradyrhizobium sp. em caupi / Co-inoculation response of growth promoting bacterias in plants and Bradyrhizobium sp. in cowpea

Para a região árida e semi-árida do Nordeste brasileiro, o cultivo do caupi (Vigna unguiculata [L.] Walp.) vem se destacando por ser uma cultura adaptável as condições da região. Devido à capacidade do caupi de, em simbiose com o rizóbio, realizar a FBN, a co-inoculação rizóbio e bactérias promotoras de crescimento em plantas (BPCP's) poderá optimizar a fixação do N2 atmosférico dependendo da combinação e compatibilidade das estirpes envolvidas. O objetivo do trabalho foi avaliar a resposta da co-inoculação de BPCP's e Bradyrhizobium sp. como alternativa para optimizar a performance simbiótica e o desenvolvimento do caupi em condições de casa-de-vegetação. O experimento foi instalado em casa de vegetação, utilizando como substrato areia lavada e autoclavada em vasos de Leonard. Os tratamentos foram: 22 estirpes de BPCP's comparadas com a estirpe padrão (BR 3267), no caupi cv. "IPA 206". A colheita foi efetuada aos 35 dias após o plantio (DAP) e foram avaliados as seguintes variáveis: altura de planta (AP) aos 15, 25 e 35 dias, comprimento da raiz (CR), matéria seca da parte aérea (MSPA), matéria seca da raiz (MSR), matéria seca do nódulo (MSN), nodulação específica (NE) e nitrogênio acumulado na parte aérea (Nac). Os resultados mostram que a cultura do caupi respondeu significativamente a inoculação de estirpes de Bacillus, Brevibacillus e Paenibacillus co-inoculados com a estirpe de Bradyrhizobium sp. (BR 3267). A interação dos micro-organismos estudados não influenciou as variáveis, nodulação específica e matéria seca dos nódulos no caupi cv. IPA 206. A estirpe de Paenibacillus graminis (MC 04.21) co-inoculada com Bradyrhizobium sp. (BR 3267) foi superior em relação às demais estirpes avaliadas na produção de nitrogênio acumulado na matéria seca da parte aérea, proporcionando uma melhor performance simbiótica.

In the arid and semi-arid northeastern Brazil, the cultivation of cowpea has stood out for being an adaptable culture conditions in the region. Because of the ability of cowpea, in symbiosis with rhizobia carry out the FBN, the co-inoculation Rhizobium and growth promoting bacteria in plants can optimize the fixation of atmospheric N2 depending on the combination and compatibility of the strains involved. The objective of this study was to evaluate the response of the inoculation BPCP's and Bradyrhizobium sp. as an alternative to optimize performance and development of symbiotic cowpea under conditions of green-house. The experiment was conducted in a greenhouse, using as substrate washed and sterilized sand in Leonard jars. The treatments were: 22 strains BPCP's compared with the strain (BR 3267), on cowpea cv. IPA 206. At harvest 35 days after planting (DAP) and the following variables were evaluated: plant height (AP) 15, 25 and 35 days, root length (CR), shoot dry matter (MSPA), root dry matter (MSR), nodule dry matter (MSN), specific nodulation (NE) and nitrogen accumulated in shoots (Nac). The results show that the culture of cowpea responded significantly to inoculation of strains of Bacillus, Brevibacillus and Paenibacillus co-inoculated with the strain of Bradyrhizobium sp. (BR 3267). The interaction of microorganisms studied non-influenced the variables specific nodulation and dry matter of nodules in cowpea cv. IPA 206. The strain of Paenibacillus graminis (MC 04/21) coinoculated with Bradyrhizobium sp. (BR 3267) was higher compared to other strains tested in the production of nitrogen accumulated in shoot dry matter, providing a better performance symbiotic.