Genetic control of early grain darkening of carioca common bean

Abstract

To obtain information on the genetic control of early darkening in common bean with carioca grain and verify the feasibility of selection by means of a grade scale, two contrasting parents were crossed, line VC-3 with cultivar BRSMG Majestoso. The seeds of F 2 plants and F 2:3 progenies were evaluated 30, 60 and 90 days after harvest for grain darkening, on a 1 -5 grade scale. Genetic and phenotypic parameters were estimated. The grade scale efficiently discriminated the progenies in terms of grain darkening. The heritability of the trait increases with the storage time and was high enough to ensure success with selection after 30 days. The genetic control seems to be monogenic with dominance of the allele for early darkening.

Genetic control and estimation of genetic parameters for seed-coat darkening of carioca beans

“…According to Basset (1996), seed-coat darkening is controlled by a single gene with alleles J and j, and the expression of the recessive allele j results in genotypes that are less susceptible to tegument darkening when compared with seeds of plants carrying the dominant allele. Results confirming that the trait is controlled by one gene with the dominance of the allele being responsible for seed-coat darkening were reported by Junk-Knievel et al (2008), Silva et al (2008), and Araújo et al (2012) using different lines. On the other hand, Elsadr et al (2011) described a model with two genes interacting under epistasis, leading to three phenotypic classes for seed-coat darkening.…”

“…In Brazil, a dark seed coat is associated with old grains with prolonged time for cooking, which induces low acceptability by the consumer. Hence, great efforts are invested in the development of light-colored-grain cultivars that maintain their color for a greater period of storage time (Silva et al, 2008).…”

Genetics of common bean resistance to white mold

“…In the first evaluation, the average performance of the progenies from each generation was similar to that of the parents, indicating that the trait was predominantly regulated by additive effects (Silva et al 2008). However, in the second evaluation the means of these populations suggested the occurrence of dominance effects.…”

BRSMG Madrepérola: common bean cultivar with late-darkening Carioca grain

“…The following traits were evaluated: grain yield (kg ha -1 ); severity of angular leaf spot, on a 1-9 scale, where 1 -plant without disease symptoms to 9 -completely infected plant; plant architecture, on a 1-9 scale, where 1 -upright plants to 9 -completely prostrate plants; degree of lodging, on a 1-9 scale, where 1 -absence of lodging to 9 -all plants lodged; number of days to flowering; and number of days to maturity. The reaction to races 55, 65, 73, 81, 89, 95, and 453 of Colletotrichum lindemuthianum was also evaluated in the laboratory, according to the methodology described by Rava et al (1994), the cooking time (in min) in a 25-seed Mattson cooker (Proctor and Watts 1987); protein content based on the total nitrogen grain content determined by the microKjedahl method using the factor 6.25 to convert total N in protein (AOAC 1980); grain coat color using a colorimeter (Minolta CR-310), which evaluates the colors along three axes in a three-dimensional system, as described by Silva et al (2008).…”

“…The grains of BRSMG Madrepérola are "Carioca" (light beige with light brown stripes), according to the consumer demands, have an average 100-grain weight of 24.5 g and maintain the color longer without darkening (around six months) than other carioca varieties on the market (Silva et al 2008). …”