Comprehensive evaluation of biosynthesis, accumulation, regulation of folate and vitamin C in waxy maize (Zea mays L. var. ceratina) with kernel development

Waxy maize presents a series of changes during kernel development. In this study, contents and gene expression profiles of folate and vitamin C during kernel development of waxy maize were explored. Six inbreds, three colors of kernels, four developing periods and two planting seasons in the same experimental fields were analyzed. We found that contents of folate and vitamin C declined overall through four development periods in both seasons, while the manners of gene expression varied, responding to different weather conditions. Key genes in synthetic pathways of folate and vitamin C corresponded to the variation of their contents. GTP cyclohydrolase (GTPCH) played an important role in the biosynthesis of folate and vitamin C during kernel development. Another key gene, dehydroascorbate reductase (DHAR), was associated with the dynamic balance of vitamin C pool in responding to weather. Considering the contents and gene expression of folate and vitamin C, results indicated that appropriate conditions (temperature, humidity, rainfall and radiation) could facilitate the kernel development of waxy maize. Furthermore, coordinate regulation might happen between the biosynthesis of folate and vitamin C. This study promoted a better understanding of the reason for choosing kernels from mid-late period of development in waxy maize harvest.