A legume biofortification quandary: variability and genetic control of seed coat micronutrient accumulation in common beans

Abstract

Common beans (Phaseolus vulgaris L.), like many legumes, are rich in iron, zinc, and certain other microelements that are generally found to be in low concentrations in cereals, other seed crops, and root or tubers and therefore are good candidates for biofortification. But a quandary exists in common bean biofortification: namely that the distribution of iron has been found to be variable between the principal parts of seed; namely the cotyledonary tissue, embryo axis and seed coat. The seed coat represents ten or more percent of the seed weight and must be considered specifically as it accumulates much of the anti-nutrients such as tannins that effect mineral bioavailability. Meanwhile the cotyledons accumulate starch and phosphorus in the form of phytates. The goal of this study was to evaluate a population of progeny derived from an advanced backcross of a wild bean and a cultivated Andean bean for seed coat versus cotyledonary minerals to identify variability and predict inheritance of the minerals. We used wild common beans because of their higher seed mineral concentration compared to cultivars and greater proportion of seed coat to total seed weight. Results showed the most important gene for seed coat iron was on linkage group B04 but also identified other QTL for seed coat and cotyledonary iron and zinc on other linkage groups, including B11 which has been important in studies of whole seed. The importance of these results in terms of physiology, candidate genes and plant breeding are discussed.

Genetic control of iron concentration in Mesoamerican and Andean common bean seeds

“…The distribution of iron between the embryo and the seed coat fractions of common bean seeds can vary among gene pools, as observed in the present study and by Ariza-Nieto et al (2007), Cvitanich et al (2010), Ribeiro et al (2012), and Blair et al (2013). Since iron is accumulated more in the embryo of the Andean Pesq.…”

“…agropec. bras., Brasília, v.50, n.5, p.383-391, maio 2015 DOI: 10.1590/S0100-204X2015000500005 However, the distribution of iron in the embryo and seed coat fractions of common bean seeds varies among gene pools and between lines of the same gene pool (Moraghan et al, 2002;Ariza-Nieto et al, 2007;Cvitanich et al, 2010;Ribeiro et al, 2012;Blair et al, 2013). This has direct consequences on iron bioavailability for the human organism (Lombardi-Boccia et al, 1995), in deciding when to start the process of selection of superior lines (Jost et al, 2009) and to determine the initial vigor of common bean seeds (Moraghan et al, 2002).…”

Achievements and Challenges in Improving the Nutritional Quality of Food Legumes

“…In legume biofortification, an additional dilemma exists due to the differential accumulation of micronutrients in the principal parts of the seed: seed coat, cotyledonary tissue and embryonic axis (Blair et al, 2013). The importance of differences in micronutrient distribution in seed coat and the rest of the seed reside in the interaction of minerals between each other and with secondary metabolites, such as tannins or phytates, that are especially concentrated in the seed coat and the cotyledonary tissues, respectively (Blair et al, 2013).…”

Highly efficient genomics-assisted development of a library of introgression lines of Solanum pimpinellifolium

“…Tanksley and Nelson (1996) introduced the advanced backcross quantitative trait locus (AB-QTL) strategy in order to integrate QTL mapping and breeding population development and to facilitate the introduction of new genetic variability from wild species into elite germplasm. Studies in tomato and other crops have shown that this method efficiently discovers favorable alleles in wild germplasm resources (Xiao et al 1998;Moncada et al 2001;Septiningsih et al 2003;Blair et al 2013). The ultimate aim of the AB-QTL approach was to make unadapted germplasm accessible to the breeder by developing introgression lines that carry the favorable QTL alleles.…”