In a significant stride toward understanding plant metabolism, researchers have identified and characterized key enzymes involved in the degradation of nicotinamide riboside (NR) in kale. This discovery, published in *Industrial Crops and Products*, opens new avenues for enhancing the nutritional value of this leafy green and potentially other crops.
Nicotinamide riboside, a precursor to nicotinamide adenine dinucleotide (NAD+), is gaining attention for its role in cellular metabolism and its potential health benefits. However, the metabolic pathway responsible for NR degradation in plants has remained elusive until now. Led by Tingting Hao of the Provincial Key Laboratory of Agrobiology and Institute of Germplasm Resources and Biotechnology at the Jiangsu Academy of Agricultural Sciences, the research team identified seven candidate nucleoside hydrolase genes in kale, of which five were successfully cloned.
“Our study provides a comprehensive analysis of nucleoside hydrolases in kale, shedding light on their role in NR metabolism,” Hao explained. The team’s in vitro assays revealed that BolNSH1, BolNSH2, and BolNSH3 efficiently hydrolyze NR to produce nicotinamide (NAM). Transient expression in *Nicotiana benthamiana* confirmed the functionality of these enzymes in vivo. Furthermore, virus-induced gene silencing (VIGS) of BolNSH1, BolNSH2, BolNSH3, and BolNSH4 in kale resulted in elevated NR levels, validating their role in NR metabolism.
The nucleoside hydrolases exhibited broad substrate specificity, hydrolyzing a range of pyridine, pyrimidine, and purine nucleosides. This finding suggests that these enzymes play a crucial role in the metabolic pathways of various nucleosides, not just NR.
The implications for the agriculture sector are substantial. By understanding and manipulating these enzymes, researchers can develop kale varieties with enhanced NR content, potentially increasing the crop’s market value as a nutraceutical. “This research lays the groundwork for creating high-value kale germplasm,” Hao noted. The ability to modulate NR metabolism in plants could also extend to other crops, offering new opportunities for agricultural innovation.
The study’s findings not only advance our understanding of plant metabolism but also pave the way for practical applications in agriculture. As the demand for nutraceuticals continues to grow, crops with enhanced NR content could become a valuable commodity. This research represents a significant step forward in the quest to develop high-value, nutritionally enhanced crops, with the potential to reshape the agricultural landscape.