Transcriptomic and metabolic analyses revealed the modulatory effect of vernalization on glucosinolate metabolism in radish (Raphanus sativus L.).

Vernalization is the process by which long-term cold like winter triggers transition to flowering in plants. Many biennial and perennial plants including Brassicaceae family plants require vernalization for floral transition. Not only floral transition, but dynamic physiological and metabolic changes might also take place during vernalization. However, vernalization-mediated metabolic change is merely investigated so far. One of secondary metabolites found in Brassiceceae family plants is glucosinolates (GSLs). GSLs provides defense against pathogens and herbivores attack in plants and also exhibits inhibitory activity against human cancer cell. Profiles of GSLs are highly modulated by different environmental stresses in Brassciaceae family plants. To grasp the effect of vernalization on GSLs metabolic dynamics in radish (Raphanus sativus L.), we performed transcriptomic and metabolic analysis during vernalization in radish. Through transcriptome analysis, we found many GSLs metabolic genes were significantly down-regulated by vernalization in radish plants. Ultra-High Performance Liquid Chromatography analysis also revealed that GSLs compounds were substantially reduced in vernalized radish samples compared to non-vernalized radish samples. Furthermore, we found that repressive histone modification (i.e. H3K27me3) is involved in the modulation of GSLs metabolism via epigenetic suppression of Glucoraphasatin Synthase 1 (GRS1) during vernalization in radish. This study revealed that GSLs metabolism is modulated by vernalization, suggestive of a newly identified target of vernalization in radish.

Correction to: Differential expression of major genes involved in the biosynthesis of aliphatic glucosinolates in intergeneric Baemoochae (Brassicaceae) and its parents during development.

Due to an unfortunate turn of events, an incorrect note was provided in the original publication as it should have read.

Differential expression of major genes involved in the biosynthesis of aliphatic glucosinolates in intergeneric Baemoochae (Brassicaceae) and its parents during development.

KEY MESSAGE: Thus study found the temporal and spatial relationship between production of aliphatic glucosinolate compounds and the expression profile of glucosinolate-related genes during growth and development in radish, Chinese cabbage, and their intergeneric hybrid baemoochae plants. Glucosinolates (GSLs) are one of major bioactive compounds in Brassicaceae plants. GSLs play a role in defense against microbes as well as chemo-preventative activity against cancer, which draw attentions from plant scientists. We investigated the temporal relationship between production of aliphatic Glucosinolate (GSLs) compounds and the expression profile of GSL related genes during growth and development in radish, Chinese cabbage, and their intergeneric hybrid, baemoochae. Over the complete life cycle, Glucoraphasatin (GRH) and glucoraphanin (GRE) predominated in radish, whereas gluconapin (GNP), glucobrassicanapin (GBN), and glucoraphanin (GRA) abounded in Chinese cabbage. Baemoochae contained intermediate levels of all GSLs studied, indicating inheritance from both radish and Chinese cabbage. Expression patterns of BCAT4, CYP79F1, CYP83A1, UGT74B1, GRS1, FMOgs-ox1, and AOP2 genes showed a correlation to their corresponding encoded proteins in radish, Chinese cabbage, and baemoochae. Interestingly, there is a sharp change in gene expression pattern involved in side chain modification, particularly GRS1, FMOgs-ox1, and AOP2, among these plants during the vegetative and reproductive stage. For instance, the GRS1 was strongly expressed during leaf development, while both of FMOgs-ox1 and AOP2 was manifested high in floral tissues. Furthermore, expression of GRS1 gene which is responsible for GRH production was predominantly expressed in leaf tissues of radish and baemoochae, whereas it was only slightly detected in Chinese cabbage root tissue, explaining why radish has an abundance of GRH compared to other Brassica plants. Altogether, our comprehensive and comparative data proved that aliphatic GSLs biosynthesis is dynamically and precisely regulated in a tissue- and development-dependent manner in Brassicaceae family members.