Banca de DEFESA: JÉSSICA DE PAULA FERREIRA
Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.STUDENT : JÉSSICA DE PAULA FERREIRA
DATE: 25/01/2021
TIME: 09:00
LOCAL: plataforma virtual Google Meet
TITLE:
Selection of efficient interactions between plant growth promoting bacteria and Brachiaria genotypes under conditions of water deficit.
KEY WORDS:
pastures, water stress, plant growth promoting bacteria
PAGES: 1
BIG AREA: Ciências Agrárias
AREA: Agronomia
SUBÁREA: Fitotecnia
SPECIALTY: Fisiologia de Plantas Cultivadas
SUMMARY:
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Abiotic stresses such as drought represent adverse environmental conditions which significantly damage plant growth and agricultural productivity. In this study, we are selecting efficient interactions between bacteria with ACC deaminase activity and Brachiaria genotypes grown under drought conditions. For this, the bacterial isolates were evaluated qualitatively and quantitatively for the activity of ACC deaminase, in addition to being also evaluated for the presence of the acdS gene in their genome. After this screening, we verified that 10 isolates showed ACC deaminase activity and had the acdS gene in their genome. Then, thirteen isolates with better performance in ACC deaminase activity were used in conjunction with Herbaspirillum frisingense GSF30T (BR11790), Gluconacetobacter diazotrophicus PAL5T and the strain Sp245 of Azospirillum brasilense in the greenhouse experiment. The trial was composed of three genotypes of Brachiaria brizantha (Marandu, Paiaguás and Xaraés) that were submitted or not to drought stress. The relative water content (RWC) and the fresh and dry mass of the plants were evaluated at 10 days after drought stress. The Marandu genotype inoculated with G. diazotrophicus strain PAL5T showed RWC values higher than that observed for the other treatments. In the case of the Paiaguás genotype, the NRB039 bacterium (N. amazonense) promoted a higher RWC value. For the Xaraés genotype, the highest RWC value was observed in plants inoculated with strain NRB058 (Pseudomonas cremoricolorata). Regarding the accumulation of biomass from the aerial part of the Marandu genotype after 10 days of stress, we observed that the strain NRB223 (A. melinis) promoted a greater accumulation of fresh mass while the strain NRB142 (Paraburkholderia silvatlantica) was responsible for the increase in dry biomass. In contrast, strains NRB096 (Bacillus safensis) and NRB124 (P. silvatlantica) favored the largest accumulation of both biomasses (fresh and dry) for the Paiaguás and Xaraés genotypes. At 30 days of stress, the bacterium NRB096 (B. safensis), promoted the largest accumulation of dry mass in the genotype Marandu while in the genotype Xaraés, the bacterium NRB086 (A. lipoferum) was the one that promoted the greatest accumulation of biomass. In Paiaguás, plants inoculated with the bacteria G. diazotrophicus PAL5T and A. brasilense Sp245 were the ones that had the best performance. The biomass accumulation of roots of the Marandu genotype was increased with the inoculation of strains NRB087 (A. oryzae) and NRB032 (Stenotrophomonas maltophilia) which promoted higher values of fresh and dry mass, respectively. In the case of the Paiaguás genotype, the largest accumulations of fresh biomass were obtained in plants inoculated with strains NRB053 (Nitrospirillum amazonense) or with BR11790 (H. frisingense GSF30T) while the strain NRB123 (N. amazonense) promoted the largest mass accumulation dry. The greatest increase in fresh root mass of the Xaraés genotype was observed in plants inoculated with the strain NRB223 (A. melinis) while the strain NRB124 (P. silvatlantica) promoted an increase in dry mass. In addition, an in vitro experiment was carried out with the genotype Paiaguás submitted to drought stress mediated by polyethylene glycol 8000 (PEG8000). Strains NRB096 (B. safensis) and NRB138 (G. diazotrophicus) promoted the greatest development of shoot and roots in the presence of 10% of PEG8000 while the bacteria NRB096 (B. safensis), NRB142 (P. silvatlantica) and BR11790 (H. frisingense GSF30T) increased root development by 20% of PEG8000. A second in vitro experiment was carried out with the genotype B. ruziziensis subjected to water stress mediated by PEG8000. The results showed that strains NRB142 (P. silvatlantica), NRB223 (A. melinis) and BR11790 (H. frisingense GSF30T) promoted the best plant development in view of the water deficit mediated by PEG. Strains NRB142 (P. silvatlantica) and NRB223 (A. melinis) that had the greatest potential for protection against water deficit in vitro studies were evaluated in a new experiment in a greenhouse with the genotypes B. brizantha cv. Paiaguás and B. ruziziensis grown in pots with soil. The plants were evaluated after exposure to drought stress for a period of 15 and 30 days and also after rehydration for 7 days. The analyzes showed a positive effect of inoculation of bacteria with ACC deaminase activity on the accumulation of biomass, stomatal conductance and chlorophyll index. In a global analysis, a different effect of the strains was observed for the different variables evaluated without the predominance of a given inoculated strain and the evaluated genotype. Even so, the results indicate that the development of inoculants with these strains can be an alternative in mitigating the negative effects of water deficit, since they promoted higher increases than inoculated plants compared to uninoculated plants. New studies are being carried out in order to evaluate more closely the protective effect of bacteria with ACC deaminase activity on Brachiaria plants submitted to water deficit.
BANKING MEMBERS:
Presidente - 538.864.458-87 - JOSE IVO BALDANI - UFRRJ
Interno - 2181674 - LEONARDO OLIVEIRA MEDICI
Externa ao Programa - 1815763 - IRENE DA SILVA COELHO
Externo à Instituição - CARLOS HENRIQUE SALVINO GADELHA MENESES - UEPB
Externo à Instituição - CLEITON DE PAULA SOARES - UENF