Effects of environment and genotype on folate contents in wheat in the HEALTHGRAIN diversity screen.

This study examined the environmental and genetic variation in folate contents and compositions of wheat genotypes. The selected genotypes, 24 from winter wheat and 2 from spring wheat, were grown in Martonvasar, Hungary, for three consecutive years as well as at four locations (Hungary, France, United Kingdom, and Poland) in one year. Total folate contents were determined by microbiological assay, and folate vitamers were determined for selected genotypes by high-performance liquid chromatography. Statistically significant differences in folate content arose among both harvesting years and growing locations. Grains grown in Hungary had the highest average folate content and those from Poland the lowest. Altogether, a 2.8-fold difference in total folate content appeared, ranging from 323 ng/g of dm (Chinese Spring, grown in Hungary in 2005) to 889 ng/g of dm (Riband, grown in Hungary in 2007). In general, the total folate content varied more greatly among the four growing locations than among the three harvesting years. Environmental factors affected folate content more strongly than genetic factors. In addition, small grains with high bran yield and low thousand kernel weight had high folate contents. The dominant vitamer in wheat genotypes was 5-HCO-H4folate. Other formylated folates and 5,10-CH+-H4folate also existed in significant amounts. Variation in the proportions of 5-HCO-H4folate and 5-CH3-H4folate were mainly responsible for the variation in total folate content: samples with high total folate content had a high proportion of 5-CH3-H4folate and a low proportion of 5-HCO-H4folate. Genotypes with both low and high folate contents, as well as with narrow or broad range, were identified. Thus, the study produced important data for plant breeding to select lines with stable folate contents.