Genetic and Physiological Regulation of Folate in Pakchoi (Brassica rapa subsp. Chinensis) Germplasm.

Background: Folates are essential micronutrient required by most living organisms. Folate deficiency in human remains prevalent due to inadequate dietary intake. Biofortification through breeding is a potential strategy to reduce widespread human folate deficiency. Genetically diverse germplasm can potentially be used as parents in breeding programs. Therefore, we investigate natural genetic diversity of folate in pakchoi genotypes grown under controlled environmental conditions.

 

Methodology/Principal Findings: Folates were extracted by a monoenzyme treatment and analyzed by a validated liquid chromatography method. The total folate content ranged from 52.7 to 166.9 μg/100 g of fresh weight, with 3.2-fold variation. The folate forms found were H₄-folate, 5-CH₃–H₄folate, and 5-HCO–H₄folate, and 10-CHO-folic acid also varied among different accessions and was responsible for variation in the total folate content. The major folate vitamer was represented by 5-CH₃-H₄folate, with 4.5-fold variation, which on average accounted for up to 54.6% of the total folate pool. A general correlation between total folate, pteridine and pABA was observed. Analysis of the transcription of 11 genes involved in folate metabolism suggested that variation in folate concentrations may be controlled primarily at the post-transcriptional level.

 

Conclusions: Transcriptional regulation of folate metabolism gene expression might contribute to the different levels of folate accumulation in pakchoi germplasm. The diverse genotypic variation in pakchoi germplasm demonstrates the great genetic potential to integrate breeding programs for folate biofortification.