Comunidades de bactérias endofíticas e epifíticas associadas à cana-de-açúcar e prospecção de promotores de crescimento em plantas
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Data
2020-09-11
Autores
Sierra, Luis Guillermo Teheran
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Universidade Estadual Paulista (Unesp)
Resumo
As bactérias associadas a plantas constituem apenas um dos grupos que conformam o microbioma, o qual é responsável pela nutrição, saúde e homeostase geral da planta. A prospecção de bactérias com traços de promoção de crescimento é uma alternativa para o aproveitamento do microbioma cultivável das plantas e é a principal fonte dos microrganismos benéficos usados como inoculantes. O presente estudo teve como objetivo investigar as comunidades de bactérias associadas aos diferentes tecidos (ambientes) de cana-de-açúcar sob duas formas de cultivo contrastantes, na forma de comunidades, tanto endofíticas como epifíticas, com capacidade de promoção de crescimento vegetal. Foram prospectadas 944 comunidades usando um meio de cultura proposto pelo grupo para conformar um banco de comunidades. Posteriormente foram testadas com experimentos in planta usando a gramínea Cynodon dactylon (grama bermuda). Posteriormente foram feitos testes de seleção baseados em características fenotípicas tais como a produção de ácido indol-acético - AIA e a capacidade de solubilização de fosfatos. Um grupo final de 17 comunidades foi caracterizado em profundidade, na busca de traços de promoção de crescimento vegetal em Brachiaria ruziziensis e outras características fisiológicas. Para identificar os membros das comunidades selecionadas, foi amplificada e sequenciada a região hipervariável V3-V4 do gene 16s rDNA na plataforma Illumina, acessando a abundância e riqueza de espécies em cada uma delas, potencial metabólico e redes de co-ocorrência, chegando no final, na identificação de 34 gêneros e 24 espécies distribuídas entre os filos Proteobacteria, Bacteroidetes, Firmicutes e Actinobacteria. Foram identificados ademais, vários gêneros com alto nível de centralidade nas análises de redes: Chryseobacterium, Leucobacter e Pseudomonas. Finalmente foram classificadas as melhores cinco comunidades promotoras de crescimento em plantas a partir das análises e testes realizados, das quais, quatro vêm de cana-de-açúcar convencional e uma de cultura orgânica, quatro de colmo, e uma de folha. Das cinco, três pertencem ao nicho endofítico e dois epifíticos, as quais tem potencial para serem exploradas como inoculantes biológicos.
Plant-associated bacteria constitute only one of the groups that constitute the microbiome, responsible for homeostasis and boost the nutrition and health of the plant. Prospecting bacteria with plant growth-promotion traits is an alternative for exploiting the cultivable microbiome of plants and offers a primary source of beneficial microorganisms used as inoculants. This study aimed to investigate bacterial communities associated with soil and sugarcane tissues under two forms of contrasting agricultural management in the form of communities, both endophytic and epiphytic, with the capacity to promote plant growth. A total of 944 communities were obtained using a new proposed culture medium to form a community bank. Later they were tested with in planta experiments using Cynodon dactylon (bermudagrass). Subsequently, selection tests based on phenotypic characteristics such as the production of 3-indoleacetic acid - IAA and the ability to solubilize phosphate were performed. A final group of 17 communities was characterized in depth, searching for plant growth-promotion traits using Brachiaria ruziziensis and other physiological characteristics. For identification of the species that constitute each of the selected communities, the hypervariable region V3-V4 of the 16s rDNA gene was amplified and sequenced in the Illumina platform, accessing the abundance and richness of species, metabolic potential, and co-occurrence networks, identifying 34 genera and 24 species distributed among the phyla Proteobacteria, Bacteroidetes, Firmicutes, and Actinobacteria. We point three genera with a high centrality level in the network analysis: Chryseobacterium, Leucobacter, and Pseudomonas. Finally, the five-best growth-promoting communities were classified from the analyses and tests performed, finding that four of them come from conventional sugar cane and one from organic culture, four from stalks, and one from the leaf. Of these five communities, three belong to the endophytic niche and two epiphytic, which can be explored as inoculants.
Plant-associated bacteria constitute only one of the groups that constitute the microbiome, responsible for homeostasis and boost the nutrition and health of the plant. Prospecting bacteria with plant growth-promotion traits is an alternative for exploiting the cultivable microbiome of plants and offers a primary source of beneficial microorganisms used as inoculants. This study aimed to investigate bacterial communities associated with soil and sugarcane tissues under two forms of contrasting agricultural management in the form of communities, both endophytic and epiphytic, with the capacity to promote plant growth. A total of 944 communities were obtained using a new proposed culture medium to form a community bank. Later they were tested with in planta experiments using Cynodon dactylon (bermudagrass). Subsequently, selection tests based on phenotypic characteristics such as the production of 3-indoleacetic acid - IAA and the ability to solubilize phosphate were performed. A final group of 17 communities was characterized in depth, searching for plant growth-promotion traits using Brachiaria ruziziensis and other physiological characteristics. For identification of the species that constitute each of the selected communities, the hypervariable region V3-V4 of the 16s rDNA gene was amplified and sequenced in the Illumina platform, accessing the abundance and richness of species, metabolic potential, and co-occurrence networks, identifying 34 genera and 24 species distributed among the phyla Proteobacteria, Bacteroidetes, Firmicutes, and Actinobacteria. We point three genera with a high centrality level in the network analysis: Chryseobacterium, Leucobacter, and Pseudomonas. Finally, the five-best growth-promoting communities were classified from the analyses and tests performed, finding that four of them come from conventional sugar cane and one from organic culture, four from stalks, and one from the leaf. Of these five communities, three belong to the endophytic niche and two epiphytic, which can be explored as inoculants.
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Palavras-chave
Amplicon, Culturômica, PGPB, Saccharum sp., Simbiose, Culturomics, Symbiosis