Sugar and Nitrate Sensing: A Multi-Billion-Year Story

Sugars and nitrate play a major role in providing carbon and nitrogen in plants. Understanding how plants sense these nutrients is crucial, most notably for crop improvement. The mechanisms underlying sugar and nitrate sensing are complex and involve moonlighting proteins such as the nitrate transporter NRT1.1/NFP6.3 or the glycolytic enzyme HXK1. Major components of nutrient signaling, such as SnRK1, TOR, and HXK1, are relatively well conserved across eukaryotes, and the diversification of components such as the NRT1 family and the SWEET sugar transporters correlates with plant terrestrialization. In plants, Tre6P plays a hormone-like role in plant development. In addition, nutrient signaling has evolved to interact with the more recent hormone signaling, allowing fine-tuning of physiological and developmental responses. The master sensors involved in sugar signaling such as TOR, SnRK1, and HXK1 are highly conserved in eukaryotes.Metabolic enzymes and nutrient transporters with moonlighting functions play a major role in sugar and nitrate signaling.Tre6P has a hormone-like function in plantsThe evolution of NRT1, SWEETS, and FLZ proteins correlates with plant terrestrialization.Components of sugar signaling did not diversify during the vascularization event.Nutrient signaling is evolutionary older than hormone signaling.Nutrient and hormone signaling networks strongly interact to fine-tune the plant response to nutrient status.