Genome-wide identification and transcriptional analysis of folate metabolism-related genes in maize kernels

Abstract

BackgroundMaize is a major staple food crop globally and contains various concentrations of vitamins. Folates are essential water-soluble B-vitamins that play an important role as one-carbon (C1) donors and acceptors in organisms. To gain an understanding of folate metabolism in maize, we performed an intensive in silico analysis to screen for genes involved in folate metabolism using publicly available databases, followed by examination of the transcript expression patterns and profiling of the folate derivatives in the kernels of two maize inbred lines.ResultsA total of 36 candidate genes corresponding to 16 folate metabolism-related enzymes were identified. The maize genome contains all the enzymes required for folate and C1 metabolism, characterized by highly conserved functional domains across all the other species investigated. Phylogenetic analysis revealed that these enzymes in maize are conserved throughout evolution and have a high level of similarity with those in sorghum and millet. The LC-MS analyses of two maize inbred lines demonstrated that 5-methyltetrahydrofolate was the major form of folate derivative in young seeds, while 5-formyltetrahydrofolate in mature seeds. Most of the genes involved in folate and C1 metabolism exhibited similar transcriptional expression patterns between these two maize lines, with the highest transcript abundance detected on day after pollination (DAP) 6 and the decreased transcript abundance on DAP 12 and 18. Compared with the seeds on DAP 30, 5-methyltetrahydrofolate was decreased and 5-formyltetrahydrofolate was increased sharply in the mature dry seeds.ConclusionsThe enzymes involved in folate and C1 metabolism are conserved between maize and other plant species. Folate and C1 metabolism is active in young developing maize seeds at transcriptional levels.

Genetic mapping of folate QTLs using a segregated population in maize

“…We investigated folate levels in maize kernels using a global germplasm collection (Yang et al 2011). 5-F-THF accounted for over 70.0% of the total folates in 70.5% of the inbred lines, which confirms that 5-F-THF is the main derivative among kernel folates (Table 1; Lian et al 2015). Further phenotyping indicated that, irrespective of significant variations across the environments, GEMS31 contained more 5-F-THF than DAN3130, and the 5-F-THF level in GEMS31 was always around 20 times that in DAN3130 (Table 2).…”

“…5‐Formyltetrahydrofolate (5‐F‐THF) is the main derivative among folates, and 5‐methyltetrahydrofolate and THF are also present in maize kernels (Lian et al ). 5‐F‐THF is a relatively stable natural folate and can be used in dietary supplementation and the treatment of cancer (Suh et al ).…”

“…The genes related to folate metabolism in maize share high sequence similarity with those in other organisms, such as Arabidopsis , rice and Escherichia coli . However, there is no significant correlation between the transcription levels of these genes and the accumulation of folates in grains, indicating that there might be other key genes regulating folate metabolism in maize (Lian et al ).…”

“…But a better understanding of folate genetic networks that control the folate accumulation in the edible parts of crops is still required, so are new candidate genes for breeding aimed at the enrichment of folates in maize kernels. 5-Formyltetrahydrofolate (5-F-THF) is the main derivative among folates, and 5-methyltetrahydrofolate and THF are also present in maize kernels (Lian et al 2015). 5-F-THF is a relatively stable natural folate and can be used in dietary supplementation and the treatment of cancer (Suh et al 2001).…”

Identification and characterization of a pathogenicity-related gene VdCYP1 from Verticillium dahliae

“…And folate as essential water-soluble B-vitamins is required by numerous organisms, especially on the plants51. During folate synthesis, dihydropteroate synthase (DHPS) acts as one of the crucial enzymes that catalyzes the condensation of dihydropteridine diphosphate and para-aminobenzoate to yield dihydropteroate5253. Sulfonamide is an analogue of para-aminobenzoate and can act as a competitive inhibitor of DHPS53 that can inhibit DHPS activity, and finally disturb the folate synthesis in Arabidopsis 51.…”