Genetic control of the seed coat colour of Middle American and Andean bean seeds

Abstract

Seed coat colour of bean seeds is decisive for acceptance of a cultivar. The objectives of this research were to determine whether there is maternal effect for "L", a* and b* colour parameters in Middle American and Andean bean seeds; to obtain estimates of heritability and gain with selection for "L", a* and b* values; and select recombinants with the seed coat colour required by the market demand. Thus, controlled crossings were carried out between the Middle American lines CNFP 10104 and CHC 01-175, and between the Andean lines Cal 96 and Hooter, for obtaining F1, F1 reciprocal, F2 and F2 reciprocal generations for each hybrid combination. Parents and generations were evaluated in two field experiments (2012 normal rainy and 2013 dry seasons) in the state of Rio Grande do Sul, Brazil. Seed coat colour was quantified with a portable colorimeter. Genetic variability for "L" (luminosity), chromaticity a* (green to red shade), and chromaticity b* (blue to yellow shade) values was observed in seeds with F2 seed coat of Middle American and Andean beans. "L", a* and b* values in bean seeds presented maternal effects. High broad-sense heritability are observed for luminosity (h(2)b: 76.66-95.07%), chromaticity a* (h(2)b: 73.08-89.31%), and chromaticity b* (h(2)b: 88.63-92.50%) values in bean seeds. From the crossings, it was possible to select bean seeds in early generation for the black group, and for carioca and cranberry types (dark or clear background) which present the colour required by the market demand.

Research Article Genetic parameters and combined selection for seed coat color and macrominerals in Mesoamerican common bean lines

“…The L*, a*, and b* values presented discontinuous variation at the F 5:6 and F 5:7 generations ( Figure 1A, 1B, 1C, 1D, 1E, and 1F), indicating that few genes act in the manifestation of the seed coat color in common bean. Similarly, Possobom et al (2015) observed the formations of few phenotypic classes for the L*, a*, and b* values determined in recombinants of Mesoamerican and Andean common bean at the F 2 generation, which characterized a qualitative inheritance. The genetic control of the darkening of carioca beans was described as governed by two genes with recessive epistatic interaction (Silva et al, 2014;Erfatpour et al, 2018).…”

“…Nevertheless, for common bean no previous studies of heritability estimates for the a* and b* values in generation of high homozygosis were found in the literature. In segregating generation, Possobom et al (2015) verified high heritability for the L*, a*, and b* values in recombinants of Mesoamerican and Andean common bean. High heritability estimates are associated with the predominance of genetic variance.…”

“…Common bean lines of black grains must have a L* value ≤ 22, because this indicates the absence of purple grains (Ribeiro et al, 2003), and are associated with fresh and fast cooking grains by consumers. In addition, a* and b* values must be close to zero, indicating the absence of a secondary color (Possobom et al, 2015). The lines L 83-17, L 69-17, and L 16-17 have L*, a*, and b* values that meet the standard for seed coat color required by breeding programs for black beans.…”

“…The emasculation of floral bud method with the interlacing of the stigmas of both parents was used to obtain the F 1 seeds, in 2012 (Possobom et al, 2015). The recombinants obtained were advanced up to the F 5 generation using the Single-Seed Descent method.…”

“…The colorimeter enables one to differentiate the seed coat color using three different parameters: L* characterizes the luminosity (dark to light); a* evaluates the variation of the green to red shades; and b* measures the variation of the blue to yellow shades. These parameters have shown to be effective for the selection of common bean lines with seed coat color pattern that satisfy consumer preference of the black and carioca beans (Ribeiro et al, 2003(Ribeiro et al, , 2008Possobom et al, 2015;Arns et al, 2018). However, the combined selection for seed coat color quantitatively evaluated by L*, a*, and b* values and macromineral concentrations (potassium, calcium, and magnesium) in Mesoamerican common bean is still unprecedented.…”