Controle genético do escurecimento dos grãos de feijão com diferentes tipos de grão e origens
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2018-02-27
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Universidade Federal de Goiás
Resumo
The darkening of bean grains (Phaseolus vulgaris L.) occurs after harvest and leads to loss of
commercial value of the product. This trait is controlled by one gene, in which the dominant allele
confers the normal grain darkening of the carioca and pinto type. In the pinto type, this gene was
denominated Sd (Slow darkening). However, there are no reports that the gene identified in pinto is the
same as in the carioca type. Molecular markers linked to the Sd gene have been identified and validated
in carioca type populations: Pvsd-1158 (SSR) and PvbHLHp12804 (SNP). Thus, this study aimed to
verify if the gene that controls the darkening of the grains in different genotypes is the same; evaluate
the efficiency of the markers Pvsd-1158 and PvbHLHp12804 in a group of genotypes with carioca and
mulatinho (cream) grains; and estimate the genetic divergence among these genotypes. For this, 17
bean genotypes were used, which were grown in two experiments in greenhouse. The harvested grains
were stored for 135 days and phenotypically evaluated for darkening. In parallel, these genotypes were
evaluated genotypically with the markers Pvsd-1158 and PvbHLHp12804 and also with a panel of 24
microsatellite markers for estimation of genetic diversity. Crossings were also performed between
genotypes 1533-15, AN512666-0 and BRSMG Madrepérola, which present slow darkening of the
grains, to confirm if the gene responsible for the slow darkening is the same. For this, progenies F2:3
were evaluated by segregation tests from the data obtained from the phenotypic evaluation of the
darkening. Considering the 17 lines,, 13 lines showed slow darkening, three presented normal
darkening and one presented no darkening. The Pvsd-1158 and PvbHLHp12804 markers presented the
expected alleles according to the phenotypic evaluation in 14 of the 16 genotypes that presented some
darkening, representing 87.5% coincidence with the phenotypic data, indicating that the Sd gene is
responsible for the darkening the grains in these genotypes. The line CNFM11940, with grains
mulatinho (cream) and the cultivar TAA Dama, with carioca grains presented slow darkening and
alleles linked to normal darkening for the two markers. This indicates that there were recombination in
this genomic region, taunting the separation between the markers and the Sd gene, or that there is
another gene conferring the slow darkening in these genotypes. Estimation of genetic divergence
among the genotypes provided additional information for comparison of the genotypes. Additionally,
all the progenies F2:3 originating from the three populations showed slow darkening and, therefore,
there was no segregation. Thus, the gene that controls the darkening of the grains in beans pinto and
carioca is the Sd gene.
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RODRIGUES, L. L. Controle genético do escurecimento dos grãos de feijão com diferentes tipos de grão e origens. 2018. 62 f. Dissertação (Mestrado em Genética e Melhoramento de Plantas) - Universidade Federal de Goiás, Goiânia, 2018.