The maize (Zea mays L.) endophytic bacteriome under different genetic, organ and cultivation site influences
The Corn (Zea mays L.) is the main cereal produced in Brazil, planted in large quantities in the semi-arid region of the Northeast. However, like all cultivation carried out in semi-arid environments, water, saline and nutritional stresses, as well as diseases caused by phytopathogens, end up limiting plant growth and annual production of those cultures. A biotechnological alternative to alleviate biotic and abiotic stresses in cultures is the inoculation of these plants with growth-promoting bacteria plant, capable of promoting positive effects of growth in the plant. However, for selection of the best candidates for these inoculums, it is necessary to study in-depth analysis of the microbiota associated with plants. To study the corn microbiome, this work promoted the massive sequencing of the 16S rRNA gene from roots and stems of 4 corn genotypes (BRS4107, BRS4105, BR5036, BR5037) planted in two different regions of the Pernambuco hinterland (Serra Talhada and Araripina). Through alpha diversity analysis, differences were detected in the richness of OTUs between the genetics (BR5037 richer than the others), and between plant organs (richer root than the culm). The stem samples showed less diversity, in contrast to the roots, by the Shannon index. There were no significant differences for indices of alpha diversity as a function of the planting site. Regarding beta diversity, in which the composition is the main element, the plant organ proved to be the main factor of influence between bacterial communities, that is, the differences between them outweigh the genetics. However, the collection area was also a significant factor in defining of the community. More than 300 genera have been identified in maize roots and stems. The genus Leifsonia, which has the phytopathogenic species Leifsonia xyli, was found in great abundance among the samples (between 3% and 40%). In the co-occurrence networks of stem samples, this genus showed strong mutual exclusion relationships with OTUs of the Enterobacteriaceae group, suggesting that they would be the most susceptible to dysbiosis caused by this bacterial genus. Other genera notable for their greater abundance were Bacillus, Klebsiella, Streptomyces, Bradyrhizobium, Pseudomonas, Acinetobacter, Geobacillus, among others. The knowledge of the corn microbiome will be used for the generation of plant growth-promoting bioinoculants.