Banca de DEFESA: EULINA BRITO MARINHO

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : EULINA BRITO MARINHO
DATE: 25/02/2026
TIME: 14:00
LOCAL: Sala 1 PPGF
TITLE:

Confirmation of hybridization between red and white rice genotypes using SSR morphological and molecular markers

KEY WORDS:

Allelic interaction; Hybrids; Polymorphism; Heterozygosity; DNA extraction.

PAGES: 61
BIG AREA: Ciências Agrárias
AREA: Agronomia
SUBÁREA: Fitotecnia
SPECIALTY: Melhoramento Vegetal
SUMMARY:

Rice (Oryza sativa L.) is of great importance to the global economy due to its socioeconomic attributes that enhance its value. Special types of rice, including red rice, have been gaining increasing market share due to their advantages, such as differentiated organoleptic properties, high nutritional value, resistance, and socio-environmental benefits. However, it is important to develop hybrids that demonstrate superiority to meet market criteria and boost the economy. This study aims to conduct hybridization between red and white rice genotypes and confirm these crosses using morphological and molecular markers. The experiment was conducted in a greenhouse and laboratory at the Federal Rural University of Rio de Janeiro (UFRRJ) and was divided into three stages. The first stage consisted of crosses between the white rice genotype 'BRS Esmeralda', used as the female parent, and two red rice genotypes, 'ENA AR1601' and 'Virginia', used as the male parents. Five 5-L pots with five seeds each were used for sowing. Thinning was performed 15 days after sowing (DAS), leaving two plants per pot. Planting was staggered, beginning in August 2024 and ending in October 2024. Two pots of each genotype were planted per week. To emasculate the female parents, the flower was cut before opening, and the anthers were manually removed with histological forceps. This process was performed on the central third of the panicle, which was protected with paper bags. Panicle preparation was performed one day before pollination. Panicles emasculated the day before were pollinated using two tillers containing two panicles (at anthesis) from the male parent, kept in a plastic tube with water next to the tillers of the female parent plant. After maturation, the hybrid seeds were harvested, dried, and stored at a refrigerated temperature (6°C). In January 2025, the two hybrid combinations—parents and controls—were sown in 11-L pots. The genotypes 'BRS 502', 'Escrevi', 'Cateto', and 'Agulhinha' were used as controls. The second step consisted of DNA extraction to select polymorphic primers (obtained from rice SSR marker sites) between the parents to confirm the crosses. The DNA from each sample was obtained in stock solution and stored at 20°C. A PCR solution was prepared in 0.2 mL microtubes, with a final volume of 15 µL per sample: 2 µL of DNA; 1.5 µL of 10X reaction; 0.9 mM MgCl₂; 2.4 µL of dNTPs (0.25 mM each); 0.1 µL of Taq polymerase (1 U); 0.6 µM of primer. The thermocycler profile was: initial cycle of 94°C for 5 min; 24 cycles of 94°C for 1 minute; 52°C for 1 minute; 72°C for 1 minute; and final extension 72°C for 7 minutes. To confirm hybridization, DNA was extracted from all plants that could be potential hybrids. Eight randomly selected DNA samples were analyzed on an agarose gel to verify primer complementarity and reproducibility. The gels were visualized and photographed using a photodocumenter. Hybrids were selected by excluding those lacking alleles of the genotypes. The third stage consisted of evaluating morphological characteristics in the hybrids, parents, and controls. A completely randomized design was used, with three replicates. The characteristics evaluated in the second stage were: leaf blade length (LLL, in cm); leaf blade thickness (LLL, in cm); flag leaf length (FLL, in cm); flag leaf thickness (FLL, in cm); flag leaf angle (FLA, in cm); stem length (SLL, in cm); basal internode diameter (BID, in mm); panicle length (PL, in cm); plant height (HH, in cm). number of viable stalks (NCV, units); number of branches (NR, units); number of fertile spikelets (NEP, units); grain length (CG, in mm); grain width (LG, in mm); and length/width ratio (L/W). The means were compared using the Scott-Knott test at 5% probability. Canonical variables were obtained from multivariate analysis of variance, with phenotypic covariance matrices and residual covariance matrices between treatments. Genetic divergence was evidenced by the dispersion of scores, in a graph (k-means) with axes represented by the first two canonical variables. The data obtained were subjected to analysis of general and specific combining ability, following the Griffing model. Overall, the hypothesis that potential hybrids can be obtained from combinations between white and red rice parents is expected to be confirmed.

COMMITTEE MEMBERS:
Presidente - 2271445 - BRUNA RAFAELA DA SILVA MENEZES
Externo ao Programa - 386054 - LUIZ BEJA MOREIRA - UFRRJExterna à Instituição - ERINA VITÓRIO RODRIGUES - UnB