Metabolic and Transcriptomic Analyses Identify Coordinated Resource Reallocation in Response to Phosphate Supply in Hemp

ABSTRACT Cannabis sativa L., one of the earliest domesticated crops, was selectively bred into drug-type (high phytocannabinoid yield) and hemp-type (fibre and seed production) varieties, resulting in divergent traits including nutrient requirements. To address the limited molecular understanding of nutrient use regulation in Cannabis, this study investigated the response of dual-purpose hemp to varying phosphate availability. Physiological and transcriptomic profiling across source and sink organs revealed that biomass partitioning to flowers was sustained unless phosphate was completely withdrawn. Analyses of key phosphate-responsive genes highlighted the importance of P reallocation to flowers via glycolytic bypass reactions and release of phosphate from organic pools in source organs. Phospholipid biosynthesis and other P-dependent metabolic pathways remained active in sink organs. While the transcriptional response of key regulators, such as SPX DOMAIN GENE (SPX), PHOSPHATE STARVATION RESPONSE1 (PHR1) and NITRATE-INDUCIBLE, GARP-TYPE TRANSCRIPTIONAL REPRESSOR1 (NIGT1) followed canonical patterns, our data suggest a lack of suppression of phosphate uptake and root-to-shoot translocation at higher phosphate supply levels. Subsequent depletion of nitrate pools restricts further growth. These findings uncover conserved and unique aspects of nutrient signalling in hemp, shedding light on its adaptation to nutrient-poor soils through distinct source–sink regulation. HIGHLIGHT Contrasting human selection in Cannabis sativa enables the analysis of divergent nutrient-use strategies. Our integrated transcriptomic and physiological data revealed adaptive resource allocation, informing the development of nutrient-efficient cultivars.