Banca de DEFESA: RAQUEL RODRIGUES GONÇALVES

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : RAQUEL RODRIGUES GONÇALVES
DATE: 31/07/2023
TIME: 14:00
LOCAL: Videoconferência Google Meet
TITLE:

DIVERSITY AND GROWTH PROMOTION POTENTIAL OF ENDOPHYTIC BACTERIA FROM DIFFERENT GENOTYPES OF FORAGE PALM

KEY WORDS:

Opuntia. Nopalea. BOX-PCR. 16S. Mechanism

PAGES: 70
BIG AREA: Ciências Agrárias
AREA: Agronomia
SUBÁREA: Ciência do Solo
SPECIALTY: Microbiologia e Bioquímica do Solo
SUMMARY:

Endophytic bacteria are found in all plant species. Plants in dry regions, such as cacti, harbor beneficial endophytic microorganisms that can be a promising solution as they have the potential to alleviate stress. Thus, the study aimed to evaluate the diversity and potential of endophytic bacteria isolated from different genotypes of forage palm for plant growth promotion. Six cultivars of palm were evaluated: IPA-20 (Opuntia fucus-indica), African elephant ear (O. undulata Griffiths), Mexican elephant ear (O. stricta Haw), small nopalea, IPA Sertânia, and F 21 (all Nopalea cochenillifera Salm Dyck). A total of 241 strains were isolated using BOX-PCR for diversity analysis, resulting in 186 groups at 100% similarity. Gene sequencing of the 16S rRNA gene was performed for bacteria containing the acdS gene, which encodes the ACC deaminase enzyme. The groups formed by BOX were tested for growth promotion mechanisms. The presence of the acdS and nifH genes was detected by PCR. IAA production was quantified by enriching the medium with L-tryptophan and using the Salkowski reagent for coloration and spectrometry for reading. Phosphate solubilization was indicated by the appearance of a halo in a medium containing insoluble phosphate. Siderophore production was conducted in an iron-free medium using the CAS reagent for coloration and analysis by spectrometry. Osmotic adaptation was tested at three stress levels (10%, 20%, and 30% PEG8000) and analyzed by optical density. Twenty-four isolates were positive for the acdS gene and sent for sequencing. Fifteen strains showed 95.04% - 99.76% similarity with strains described in the BLAST, identified in 3 phyla, 4 classes, 7 orders, 9 families, and 10 genera: Ralstonia, Bacillus, Pseudomonas, Staphylococcus, Desertihabitans, Stenotrophomonas, Priestia, Citrobacter, Micrococcus, and Acinetobacter. In the in vitro evaluation, 41 strains amplified the nifH gene. Thirty strains were IAA producers, 15 strains were able to solubilize calcium phosphate, 75 strains produced siderophores, and 66 isolates withstood osmotic stress at least at one level. The strains were grouped based on the number of mechanisms they produced: 75 produced only one mechanism, 55 had two mechanisms, 17 had three mechanisms, and only 4 presented 4 mechanisms. Statistical tests showed no significant difference in the quantity of isolates among palm genera. However, the genus Opuntia had more isolates producing mechanisms compared to the genus Nopalea, and out of the 15 strains classified at the genus level, 14 were Opuntia. The bacteria isolated from forage palm demonstrated in vitro capacity to promote growth. However, further in vivo tests are necessary to confirm their efficiency in different situations

COMMITTEE MEMBERS:
Presidente - MARIO DE ANDRADE LIRA JUNIOR
Interna - GISELLE GOMES MONTEIRO FRACETTO
Externo à Instituição - ERIC XAVIER DE CARVALHO - IPA