Diversidade de bactérias epífitas e endofíticas da cultura do milho
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Data
2017-06-30
Autores
Milani, Rafael de Mello [UNESP]
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Universidade Estadual Paulista (Unesp)
Resumo
Bactérias que habitam os tecidos externos e internos de plantas sem lhes causarem prejuízos são conhecidas como epífitas e endofíticas, atuando como promotoras de crescimento em plantas ou agindo como agentes de controle biológico. Dentre os benefícios proporcionados por essas bactérias, destacam-se a solubilização do fósforo, a fixação do nitrogênio e a produção de ácido indol acético (fitohormônio), mas também a resistência a patógenos e a adaptação a situações de estresse. Os desafios da agricultura moderna e a importância da cultura do milho exigem inovações como o uso de microrganismos promotores de crescimento. Nesse sentido, o objetivo do presente estudo foi de isolar e caracterizar bactérias epífitas e endofíticas obtidas da cultura do milho com capacidade solubilizar fósforo, fixar nitrogênio e produzir ácido indol acético. O isolamento resultou em 320 isolados retirados das folhas, caules e raízes, sendo 57% epífitas e 43% endofíticas. Foram selecionados 10 isolados, todas solubilizadoras de fósforo e fixadoras de nitrogênio, além de produtoras de ácido indol acético, que também foi quantificado e comparadas ao controle positivo. Os microrganismos selecionados foram submetidos à reação em cadeia da polimerase (PCR) e análise da porção 16S do rDNA, sendo que a identificação resultou em três espécies bacterianas diferentes, 8 Bacillus subtilis, 1 Bacillus velezensis e 1 Lactococcus lactis, encontradas nos diferentes órgãos vegetais.
Bacteria that inhabit the external and internal tissues of plants without damaging them are known as epiphytes and endophytes, acting as growth promoters in plants or acting as biological control agents. Among the benefits provided by these bacteria, phosphorus solubilization, nitrogen fixation and the production of indole acetic acid (phytohormone), as well as resistance to pathogens and adaptation to stress situations are noteworthy. The challenges of modern agriculture and the importance of maize culture require innovations as the use of plant growth microorganisms, in this way the present study had as aim to isolate and characterize the epiphytic and endophytic bacteria obtained from maize culture with the ability to solubilize phosphorus, fix nitrogen and produce indole acetic acid. Isolation resulted in 320 isolates from leaves, stems, and roots, being 57% epiphytic and 43% endophytic. Ten isolates, all phosphorus solubilizers, and nitrogen fixers were selected, as well as indole acetic acid producers, which were also quantified and compared to the positive control. The selected microorganisms were submitted to polymerase chain reaction (PCR) and analysis of the 16S portion of rDNA, and the identification resulted in three different bacterial species, 8 Bacillus subtilis, 1 Bacillus velezensis and 1 Lactococcus lactis, found in the different plant organs.
Bacteria that inhabit the external and internal tissues of plants without damaging them are known as epiphytes and endophytes, acting as growth promoters in plants or acting as biological control agents. Among the benefits provided by these bacteria, phosphorus solubilization, nitrogen fixation and the production of indole acetic acid (phytohormone), as well as resistance to pathogens and adaptation to stress situations are noteworthy. The challenges of modern agriculture and the importance of maize culture require innovations as the use of plant growth microorganisms, in this way the present study had as aim to isolate and characterize the epiphytic and endophytic bacteria obtained from maize culture with the ability to solubilize phosphorus, fix nitrogen and produce indole acetic acid. Isolation resulted in 320 isolates from leaves, stems, and roots, being 57% epiphytic and 43% endophytic. Ten isolates, all phosphorus solubilizers, and nitrogen fixers were selected, as well as indole acetic acid producers, which were also quantified and compared to the positive control. The selected microorganisms were submitted to polymerase chain reaction (PCR) and analysis of the 16S portion of rDNA, and the identification resulted in three different bacterial species, 8 Bacillus subtilis, 1 Bacillus velezensis and 1 Lactococcus lactis, found in the different plant organs.
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Palavras-chave
AIA, Nitrogênio, PCR, Promotoras de crescimento, Solubilização de fósforo, Nitrogen, Growth promoters, Phosphorus solubilization