Banca de QUALIFICAÇÃO: MARIANA CAROLINE GUIMARÃES XAVIER

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
STUDENT : MARIANA CAROLINE GUIMARÃES XAVIER
DATE: 28/08/2026
TIME: 09:00
LOCAL: On line
TITLE:

MOLECULAR AND PALYNOLOGICAL CHARACTERIZATION AND POLLEN VIABILITY VIA COLORIMETRY IN RED RICE GENOTYPES

KEY WORDS:

Oryza sativa L.; pigmented rice; pollen grain; SSR markers.

PAGES: 27
BIG AREA: Ciências Agrárias
AREA: Agronomia
SUBÁREA: Fitotecnia
SPECIALTY: Melhoramento Vegetal
SUMMARY:

Red rice (Oryza sativa L.) represents a genetic resource of interest for breeding programs, as it combines genetic diversity with a high content of bioactive compounds in the pericarp. Analyzing genetic diversity and pollen viability in red rice is crucial for understanding its genetic and reproductive potential. Characterizing genetic diversity allows for the identification of variability among genotypes, contributing to the conservation of genetic resources, the identification of promising materials, and the selection of traits of interest for breeding programs. Concurrently, assessing pollen viability provides essential information on the reproductive capacity of genotypes, which is particularly important for planning crosses and obtaining hybrids and segregating populations. Thus, this study aimed to characterize the genetic variability of rice genotypes using microsatellite (SSR) markers, describe the pollen morphology of the ‘Vermelho Virgínia’ genotype, and compare the pollen viability of five genotypes using colorimetry with Lugol’s solution and Alexander’s stain. In the molecular characterization, eight SSR markers were used, with two to three alleles per locus and a mean PIC of 0.3395; markers Pikh MAS (0.5694) and RM224 (0.5169) showed the highest values. Mean expected heterozygosity was 0.402, and observed heterozygosity was 0.3785. Tocher’s clustering method distributed the 15 genotypes into ten groups, revealing genetic differentiation among the genotypes and segregating generations. Palynological characterization was performed following acetolysis. Pollen grains of the ‘Vermelho Virgínia’ genotype exhibited medium size, oblate-spheroidal shape, a single pore-type aperture, and a thin exine; Mean diameters ranged from 36.00 to 36.75 µm, and coefficients of variation for diameter were low, whereas the greatest variations occurred in measurements associated with the exine. In the colorimetric analysis, the overall mean viability was 93.41%, with effects observed for genotype and the interaction with the stain. ‘BRS Esmeralda’, ‘ENA AR 1601’, and ‘Vermelho Virgínia’ showed the highest means, while F2 generation genotypes exhibited lower viability—particularly the ‘BRS Esmeralda’ × ‘Vermelho Virgínia’ cross with Alexander stain and the ‘BRS Esmeralda’ × ‘ENA AR 1601’ cross with Lugol’s solution. The results reinforce the utility of integrating molecular markers and reproductive traits for selecting parents and monitoring segregating populations of red rice.

COMMITTEE MEMBERS:
Presidente - 2271445 - BRUNA RAFAELA DA SILVA MENEZES
Externa ao Programa - 3470085 - TATIANA DE OLIVEIRA PINTO - UFRRJExterna à Instituição - HELLEN CRISTINA DA PAIXÃO MOURA - UFRB
Externa à Instituição - JOSIE CLOVIANE DE OLIVEIRA FREITAS - UEG