Investigation of Genotype by Environment Interactions for Seed Zinc and Iron Concentration and Iron Bioavailability in Common Bean

Abstract

Iron and zinc malnutrition are global public health concerns afflicting mostly infants, children, and women in low- and middle-income countries with widespread consumption of plant-based diets. Common bean is a widely consumed staple crop around the world and is an excellent source of protein, fiber, and minerals including iron and zinc. The development of nutrient-dense common bean varieties that deliver more bioavailable iron and zinc with a high level of trait stability requires a measurement of the contributions from genotype, environment, and genotype by environment interactions. In this research, we investigated the magnitude of genotype by environment interaction for seed zinc and iron concentration and seed iron bioavailability (FeBIO) using a set of nine test genotypes and three farmers’ local check varieties. The research germplasm was evaluated for two field seasons across nine on-farm locations in three agro-ecological zones in Uganda. Seed zinc concentration ranged from 18.0 to 42.0 μg g–1 and was largely controlled by genotype, location, and the interaction between location and season [28.0, 26.2, and 14.7% of phenotypic variability explained (PVE), respectively]. Within a genotype, zinc concentration ranged on average 12 μg g–1 across environments. Seed iron concentration varied from 40.7 to 96.7 μg g–1 and was largely controlled by genotype, location, and the interaction between genotype, location, and season (25.7, 17.4, and 13.7% of PVE, respectively). Within a genotype, iron concentration ranged on average 28 μg g–1 across environments. Seed FeBIO ranged from 8 to 116% of Merlin navy control and was largely controlled by genotype (68.3% of PVE). The red mottled genotypes (Rozi Koko and Chijar) accumulated the most seed zinc and iron concentration, while the yellow (Ervilha and Cebo Cela) and white (Blanco Fanesquero) genotypes had the highest seed FeBIO and performed better than the three farmers’ local check genotypes (NABE-4, NABE-15, and Masindi yellow). The genotypes with superior and stable trait performance, especially the Manteca seed class which combine high iron and zinc concentrations with high FeBIO, would serve as valuable parental materials for crop improvement breeding programs aimed at enhancing the nutritional value of the common bean.

Redefining Bean Iron Biofortification: A Review of the Evidence for Moving to a High Fe Bioavailability Approach

“…In summary, the study by Katuuramu et al (2021), appears to be the only published study demonstrating the GxE effect on bean Fe concentration. Most importantly this study is a 2 year "on farm" trial thus demonstrating the variance in Fe concentration that can occur once varieties are released to farmers.…”

“…To illustrate the E and GxE effect on Fe concentration, consider the results illustrated in Figure 3. In this study, Fe concentration of 10 bean varieties grown across 2 consecutive growing seasons in 9 different agroecologies in Uganda is summarized (Katuuramu et al, 2021). The results clearly show high variability across location for any given variety, ∼30-40 µg/g.…”

“…The most profound evidence for this perspective is exemplified in a recent study of beans from countries of East Africa, where varieties released as "biofortified" were found to be no different than nonbiofortified lines present in the marketplace (Glahn et al, 2020). Moreover, a recent "on farm" study in Uganda demonstrates the difficulty of consistently producing beans high in Fe that can deliver more bioavailable Fe (Katuuramu et al, 2021). Indeed, in this region it appears that the high rates of iron deficiency anemia have evolved and persisted in the presence of bean varieties that are substantially higher (∼20 µg/g) than the assumed average Fe concentration of non-biofortified beans.…”

“…Each value represents the mean of two field replicates per genotype from each location for field season 2015 and 2016 (n = 179). Adapted fromKatuuramu et al (2021).…”

Phenotype based clustering, and diversity of common bean genotypes in seed iron concentration and cooking time

“…It is worth noting that genotype by environment interaction (GxE) was reported as a factor influencing iron concentration in a variety [ 11 ]. A recent study indicated that seed iron concentration was largely controlled by genotype, location, and the interaction between genotype, location, and season which represented 25.7, 17.4, and 13.7% of phenotypic variation, respectively [ 12 ]. Defining the target population of environments such as sets of farms in which the varieties produced by a breeding program would be grown could lessen GxE effects on iron.…”