Genetic mapping of folate QTLs using a segregated population in maize

Abstract

As essential B vitamin for humans, folates accumulation in edible parts of crops, such as maize kernels, is of great importance for human health. But its breeding is always limited by the prohibitive cost of folate profiling. The molecular breeding is a more executable and efficient way for folate fortification, but is limited by the molecular knowledge of folate regulation. Here we report the genetic mapping of folate quantitative trait loci (QTLs) using a segregated population crossed by two maize lines, one high in folate (GEMS31) and the other low in folate (DAN3130). Two folate QTLs on chromosome 5 were obtained by the combination of F2 whole‐exome sequencing and F3 kernel‐folate profiling. These two QTLs had been confirmed by bulk segregant analysis using F6 pooled DNA and F7 kernel‐folate profiling, and were overlapped with QTLs identified by another segregated population. These two QTLs contributed 41.6% of phenotypic variation of 5‐formyltetrahydrofolate, the most abundant storage form among folate derivatives in dry maize grains, in the GEMS31×DAN3130 population. Their fine mapping and functional analysis will reveal details of folate metabolism, and provide a basis for marker‐assisted breeding aimed at the enrichment of folates in maize kernels.

Catalysis of 5-methyltetrahydrofolate to MeFox facilitates folate biofortification in crops

“…In this investigation, a genome-wide association study (GWAS) was conducted using a maize association panel containing hundreds of maize inbred lines genotyped by more than 1 million genome-wide single nucleotide polymorphisms (SNPs) 26,27 . We showed that ZmCTM (catalysis of 5-M-THF to MeFox) maps to a previously described quantitative trait locus 28 and encodes a protein that catalyses 5-M-THF to MeFox. The natural A-to-G variation explained 27.6% of the phenotypic variation, and led to a natural asparagine (Asn, N)-to-glycine (Gly, G) substitution in ZmCTM, which enhances its enzymatic activity.…”

“…A commercial collection of 47 fresh corn hybrids were collected from Shanghai, Guangdong, Beijing, and Sichuan (all in China) and grown in in Hebei (China) in 2020. Field experiments followed the procedures described previously 40 . For the 143 inbred lines, one row was planted for each inbred line and at least three ears in each row were selfpollinated and harvested for folate profiling of mature seeds (Supplementary Result 1).…”

Genomics-Integrated Breeding for Carotenoids and Folates in Staple Cereal Grains to Reduce Malnutrition

“…Folates are quantitative or polygenic traits typically controlled by several small effect QTLs. However, two major effect QTLs namely, q5−F−THFa and q5−F−THFb, explaining 26.7 and 14.9% of the folate variation were identified in maize (Guo et al, 2019) on chromosome 5 by whole−exome sequencing and F 3 kernel−folate profiling. A unique correlation between the folate and the expression of the conserved genes of folate biosynthesis and metabolism was reported in the kernels of maize (Lian et al, 2015).…”

Maize biology: From functional genomics to breeding application

“…The SWI/SNF (SWItch/Sucrose Non‐Fermentable) chromatin remodeling factor deficient in DNA methylation 1 (DDM1) has been demonstrated to play key roles in mediating all three contexts of DNA methylation in parallel with the RNA‐directed DNA methylation (RdDM) pathway in Arabidopsis (Zemach et al ). However, in maize, DDM1 is newly identified to regulate the formation of mCHH islands via the RdDM pathway, highlighting that the machineries of DNA methylation are evolutionarily diverged in different species (Long et al ). This mechanism was also revealed in another independent study (Fu et al ).…”

“…The genes have the potential to be used as molecular markers in breeding of salt‐tolerant maize cultivars in the future. Guo et al () used the quantitative trait loci (QTL) mapping strategy to explore the genes associate with folate content in mature kernels. Two major folate QTL on chromosome 5 were mapped which contributed 41.6% of the phenotypic variation of 5‐formyltetrahydrofolate, the most abundant storage form among folate derivatives, which is of great importance for human health.…”