Chengtai Yan

Indolic glucosinolates are a group of plant secondary metabolites found in Brassica vegetables, and their breakdown products could act as important anti-cancer and defense compounds against biotic stresses. Transcriptional regulation plays a key role in modulating the biosynthesis of indolic glucosinolates in the model plant Arabidopsis, but little is known about the transcriptional regulatory landscape of these glucosinolates in Brassica vegetables. In this study, we selected and functionally validated the important biosynthetic gene BolCYP83B1 from the indolic glucosinolate pathway in cabbage. Through a yeast one-hybrid assay, we systemically screened and identified upstream regulators of BolCYP83B1 in cabbage with BolANTs as the top candidates for further functional validation. Two homologs of BolANTs, BolANT1 and BolANT3, were confirmed to bind the promoter of BolCYP83B1 via both a yeast one-hybrid assay and an LUC assay. The overexpression of BolANT3 in cabbage significantly increased the accumulation of indolic glucosinolates, while the virus-induced gene silencing (VIGS) of BolANT3 significantly reduced the accumulation of indolic glucosinolates in cabbage. Our work provides valuable insights into the transcriptional regulatory mechanisms of indolic glucosinolates in Brassica vegetables.

Aliphatic glucosinolates are an abundant group of plant secondary metabolites in Brassica vegetables, with some of their degradation products demonstrating significant anti-cancer effects. The transcription factors MYB28 and MYB29 play key roles in the transcriptional regulation of aliphatic glucosinolates biosynthesis, but little is known about whether BoMYB28 and BoMYB29 are also modulated by upstream regulators or how, nor their gene regulatory networks. In this study, we first explored the hierarchical transcriptional regulatory networks of MYB28 and MYB29 in a model plant, then systemically screened the regulators of the three BoMYB28 homologs in cabbage using a yeast one-hybrid. Furthermore, we selected a novel RNA binding protein, BoRHON1, to functionally validate its roles in modulating aliphatic glucosinolates biosynthesis. Importantly, BoRHON1 induced the accumulation of all detectable aliphatic and indolic glucosinolates, and the net photosynthetic rates of BoRHON1 overexpression lines were significantly increased. Interestingly, the growth and biomass of these overexpression lines of BoRHON1 remained the same as those of the control plants. BoRHON1 was shown to be a novel, potent, positive regulator of glucosinolates biosynthesis, as well as a novel regulator of normal plant growth and development, while significantly increasing plants’ defense costs.

Cabbage (Brassica oleracea L. var. capitata) is an excellent source of glucosinolates (GLS) that could reduce the risk of chronic diseases. The purpose of this study was to investigate the biological traits, pigment contents, color, and GLS content of 13 cabbage varieties. This study found that there were significant differences in the GLS content for various developmental stages of cabbage varieties, and the accumulation of GLS in young leaves was higher than that in mature stages. In most of the samples, the GLS content accumulated in different parts and changed as inner leaf > middle leaf > condensed stem > root. Double haploids of the M18-15 variety may be good candidates for future breeding programs and consumers, due to their high GLS content (ranging from 201.10 to 396.25 nmol mg⁻¹ FW). GLS also act as a defense substance, and the data related to GLS accumulation patterns in different leaf locations and root parts may be useful for understanding leaf defense mechanisms and potential source–sink relationships. In addition, the observed interspecific variability is beneficial for breeders to develop Brassica varieties with high GLS content, as well as for the development of new functional food additives.