Microrganismos benéficos cultiváveis associados a Ananas spp. em diferentes ambientes

Abstract

CAPÍTULO 1 = The interactions between plants and soilborne microorganisms and endophytes have been highlighted in works, especially those involving beneficial microorganisms and their role in promoting plant growth and biocontrol of phytopathogens. However, studies on the composition of the microbiota associated with pineapple (Ananas spp.) are scarce. This work aimed to compare the diversity of microorganisms in association with Ananas spp., considered by the literature as beneficial, in ex situ conservation environment (Germoplasm Active Bank), of commercial cultivation and naturally occurring, in order to allow the conservation of isolates and the future use in Ananas spp. production. For this, samples were collected in three states, Bahia, Mato Grosso and Rondônia, followed by analysis of the composition of the cultivable microbiota associated with Ananas ssp. The samples were subdivided into different fractions: rhizospheric soil; soil of the rhizoplano; root; stem and leaf, and subjected to quantification of bacterial and fungal populations by counting colony forming units in basic culture media (bacteria and fungi) and selective for the main functional groups of microorganisms (siderophores producing bacteria [BPS ], endospores producing bacteria [BPE], actinobacteria and Trichoderma spp.). A total of 829 isolates were obtained, being 385 fungal and 444 bacterial. Analyzes based on the amplification of the ERIC and BOX repeating regions of the fungal and bacterial isolates obtained were used for the estimative of diversity of the samples. There was predominance of bacteria for the three environments, commercial field, ex situ and natural, with density of 79.7%, 89.5% and 88.8% respectively. The actinobacteria group were more representative in the ex situ environment, with 6.6 x 106 CFU.g-1, whereas in the other environments the BPSs presented the highest density, with 8.0 x 106 CFU.g-1 and 6.9 x 106 UFC.g-1, for the natural and commercial field environments respectively. The ERIC-PCR and BOX-PCR techniques allowed the grouping of microorganisms independent of the original sample, suggesting a similar distribution of the groups among samples from soil to plant shoot, especially those obtained on commercial production fields. In addition, there is a correlation between soil samples and functional groups, which indicates a requirement for these groups by plants. The obtained result for the inoculation of the isolates on micropropagated pineapple plants of the cv. „BRS Imperial‟ indicated the presence of fungi and bacteria with potential to promote growth in Ananas spp. and for biothecnological use, especially for those isolates obtained on commercial production fields. CAPÍTULO 2 = Brazil is among the world's largest fruit producers, with emphasis on pineapples (Ananas comosus var. comosus (L.) Merril y). It is believed that Ananas spp. maintain relations with a range of microorganisms, phytopathogenic or beneficial. However, studies on the microbial diversity associated with pineapple plants are still scarce. In this sense, the present work aimed to quantify and compare the diversity of microorganisms considered in the literature as beneficial, existing in the rhizospheric soil and the internal tissues of Ananas spp. from an environment of natural occurrence, commercial cultivation fields and ex situ conservation. For this, culture-dependent methods were applied, as well as molecular techniques with BOX and ERIC markers for characterization of the obtained samples and its fractions. These techniques allowed the grouping of isolates from different samples, such as those of soil, root and stem, in the same cluster, allowing to infer that there is a distribution of functional groups from soil to aerial parts of plants. In addition, correlation analyzes indicated the association of certain functional groups with the samples, which suggests that the plants are always requiring the same groups of microorganisms. CAPÍTULO 3 = The study of bacteria and fungi that compose the rhizospheric and endophytic microbiome of the genus Ananas, collected in their natural or cultivated environment, present an enormous potential for the discovery of biotechnological tools of agricultural interest, besides the possibility of restoration of the balance of agroecosystems. In this sense, the present study aimed to analyze the response of micropropagated plants of the BRS Imperial cultivar to the inoculation of fungi and bacteria isolated from rhizospheric soil and of natural and cultivated pineapple tissues. Twenty-five treatments were evaluated in a completely randomized design, being seven based on the mixture of bacteria from natural environment and seven from commertial fields, five treatments received mix of fungi from natural environment and five from commertial fields. The results showed that are fungi and bacteria with potential to promoth growth in pineapples plants, especially those from commercial field environment, seince that some treatments were able ensure high survive rates of the plants (> 90%) and promote gains on different agronomic traits such as dry and fresh matter, plant size, diameter of the rosett and number of leaves.