Rizobactérias promotoras de crescimento de plantas associadas à Pereskia aculeata Mill.: potencial biotecnológico e identificação

Abstract

The ora-pro-nóbis (Pereskia aculeata) is a rustic species that grows well in diverse soils that have not necessarily been fertilized. In addition, the cultivation and consumption of this plant, as well as other non-conventional food plants, contribute to the promotion of food and nutritional security by its value in the preservation and rescue of food culture. Studies with non-conventional food plants also corroborate for their relevance in building and maintaining a healthier and more sustainable food system. Previous studies developed by Vega (2020) and collaborators found that the high protein content of ora-pro-nobis is not related to organic matter or nitrogen content in the soil and were identified the occurrence of associative bacteria of the genus Azospirillum predominantly in roots and rhizosphere of the plant. The genus Azospirillum represents an important group of associative bacteria that have the ability to promote plant growth. Thus, the objective of the study was to understand the behavior of this plant under water stress and the response of the microbiota associated with ora-pro-nóbis with the help of biological indicators, in addition to testing strains previously isolated (UFLA0261, UFLA0267T, UFLA0306T, UFLA0324, UFLA0346 and UFLA0327T), separately on pumpkin seed, co-inoculated in cowpea (cultivar quarantão) and genomic analysis of some strains previously selected (UFLA0325T, UFLA0267T, UFLA0327T and UFLA0306T). Microbial parameters, with few exceptions, did not vary between propagation methods and when compared over time. For microbial biomass carbon there were higher values with 14 consecutive days of irrigation suspension in the treatment with plants from seeds and the control irrigated in cuttings. Soil biomass respiration was highest in the control treatment and with 32 days without irrigation for seed propagation. The trials with co-inoculation in cowpea bean and inoculation in pumpkin seedling did not show statistical differences. All treatments were similar to the control with mineral nitrogen, except when inoculated with UFLA0306. Results of genomic analyses confirmed the existence of four new species, for which the names Azospirillum itumirinense (UFLA0325T), Azospirillum uflense (UFLA0267T), Azospirillum lavrensis (UFLA0327T) and Pseudomonas ijaciense (UFLA0306T) were proposed and considered as type strains.