Banca de QUALIFICAÇÃO: FABÍOLA KELLY NASCIMENTO DOS SANTOS

Ammonium-excreting diazotrophic bacteria and overproducers of indoles with the potential to maximize upland rice grain production

Upland rice; Plant-bacteria interactions; Sustainable Agriculture

Diazotrophic bacteria are known for their ability to fix atmospheric nitrogen and,
among other functional capabilities, many are capable of producing auxin in large quantities
for plant growth promotion. However, ammonium excretion and
overproduction of auxin are not commonly identified features in these bacteria.
Through these characteristics, diazotrophic bacteria can have these potentiated effects
in plant growth and development. For this reason, the objective of this work is to
to select bacteria-derived indole overproducers and ammonium excretors mutants
diazotrophs through the evaluation of the potential as a bioinoculant for the rice crop of
upland. A total of 52 strains that are deposited in the Genetics and Biochemistry laboratory
from Embrapa Agrobiologia will be evaluated in this work. These strains come from
genetic mutations induced by chemical agents, of which 19 are potentially
ammonium excretors from wild-type PAL5 strains of the Gluconacetobacter 
diazotrophicus, SP245 from Azospirillum baldaniorum and others from the CBAMC strain of the species
Nitrospirillum amazonense. In addition to these, 33 are potentially overproducer mutants of
auxin from strain SP245. The abilities of these mutants to overproduce
auxin or excrete ammonium, have not been tested so far, so they will initially be
in vitro tests were performed to confirm these physiological characteristics. Furthermore, they will
evaluated  in a greenhouse to verify the potential of these mutants in the
growth of rice plants. Finally, the genomes of the most promising mutant strains
in rice growth promotion will be evaluated and compared with the genomes of
wild strains in order to verify the corresponding “improved” genetic component
to the promising phenotype. At least two mutant strains are expected to demonstrate effects
beneficial in the development of rice plants, showing potential to be used
as promising biofertilizers.