Banca de DEFESA: ERINALDO GOMES PEREIRA

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
STUDENT : ERINALDO GOMES PEREIRA
DATE: 25/11/2022
TIME: 13:30
LOCAL: sala 24
TITLE:

Contribution of variations in DNA methylation profile and metabolic and physiological changes to adaptation of rice (Oryza sativa L.) plants to low-nitrogen cropping systems

KEY WORDS:

Rice, nitrogen, stress, epigenetic, methylation; demethylation

PAGES: 116
BIG AREA: Ciências Agrárias
AREA: Agronomia
SUBÁREA: Ciência do Solo
SUMMARY:

Nitrogen (N) deficiency is an abiotic stress to which rice plants are susceptible to throughout the crop cycle, mainly due to the high demand for N presented by this crop and also because of the easy loss of this nutrient in the soil. DNA methylation is an epigenetic mechanism that affects plant performance in the face of various environmental stresses. The objectives of this research were: 1) to verify if rice plants submitted to low N stress modify their DNA methylation profile; 2) to verify possible alterations in the DNA methylation profile, morpho-physiological, metabolic changes, and gene expression in rice plants submitted to different crop cycles with low N; 3) to establish relationships between DNA methylation modifications and morpho-physiological and metabolic changes; 4) to determine if exposure to low N cycles results in plants better adapted to this condition. For this, the rice varieties Esmeralda (improved), Manteiga and Piauí (traditional from Maranhão state), were subjected to the following treatments: Control - plants grown with N-sufficient (60 kg N ha^-1) for three successive crop cycles; NS1 - plants grown with low N (10 kg N ha^-1) only in the last crop cycle (first stress exposure); NS2 - plants grown with low N in the first and third crop cycle (intermittent stress); NS3 - plants grown with low N for three successive cycles (recurrent stress). A reduction in total DNA methylation was verified in plants of the Esmeralda variety grown with low N compared to the control. Plants submitted to the low N treatments showed a greater reduction in the number of hemi-methylated bands at the expense of fully methylated bands. The most severe reduction in the number of hemi-methylated bands was seen in plants submitted to the NS2 treatment, which was accompanied by a more significant increase in the number of fully methylated bands. This modification in the DNA methylation pattern observed in NS2 was followed by a reduction in grain yield, photosynthetic efficiency, and N use efficiency related parameters. The varieties Manteiga and Piauí showed a significant increase in the total number of methylated bands when subjected to the low N stress treatments compared to the control. This result was mainly due to a strong increase in the number of fully methylated bands. Plants subjected to the NS2 and NS3 treatments had a more significant increase in the number of fully methylated bands, and a decrease in the number of hemi-methylated bands. This modification in methylation pattern was accompanied by higher grain yield, improved photosynthetic efficiency, increased N use efficiency, and changes in gene expression. The results of this study demonstrate that exposure to low N alters the DNA methylation pattern, and that the type and intensity of this alteration depend on both the duration of stress and the varieties under study. Changes in the DNA methylation pattern are accompanied by morpho-physiological, metabolic, and gene expression modifications. Exposure to intermittent and recurrent stress improves the performance of the varieties Manteiga and Piauí, whereas intermittent stress is detrimental to the variety Esmeralda.

COMMITTEE MEMBERS:
Externa à Instituição - CLICIA GRATIVOL GASPAR DE MATOS - UENF
Externo ao Programa - 1809123 - ANDRE MARQUES DOS SANTOS - nullInterno - 1399485 - ANDRES CALDERIN GARCIA
Presidente - ***.180.573-** - MANLIO SILVESTRE FERNANDES - UFRRJ
Externa à Instituição - MARCIA SOARES VIDAL - EMBRAPA