Integrated transcriptomic and metabolomic analysis reveals key genes and core metabolic pathways involved in phosphorus stress response in quinoa flower spikes.

BACKGROUND: Quinoa is native to the Andes Mountains, where the ecological environment is relatively harsh, making it highly resilient in adapting to its environment. In the flower spike stage, phosphorus (P) is vital for plant metabolism and signaling. Here, we analyzed the flower spike response to low and high P stress. RESULTS: A total of 1891 metabolites were identified among the three subgroups: control (CB, CY), high P (HB, HY), and low P (LB, LY), where Y represents Dianyuli 1, and B represents Dianyuli 3. There were 290 and 164 differentially expressed metabolites (DAMs) in LB vs. CB and LY vs. CY, respectively, and 144 and 248 DAMs in HB vs. CB and HY vs. CY, respectively. A total of 53,202 genes were annotated using transcriptome analysis, with 2,818 and 3,628 differentially expressed genes (DEGs) in LB vs. CB and LY vs. CY, respectively, and 263 and 3,702 DEGs in HB vs. CB and HY vs. CY, respectively. The main molecular mechanisms of quinoa floral spikes were different under low and high P conditions, with the main pathways under low P stress being purine, starch, and sucrose metabolism, glycolysis, and flavonoid biosynthesis. The primary pathways involved in high P stress were pyrimidine, alanine, aspartate, and glutamate metabolism, and phenylpropanoid and flavonoid biosynthesis. The synthesis pathways indicated that sugars, organic acids, flavonoids, nucleotides, and their derivatives were involved in the P stress response mechanisms of quinoa flower spikes. Joint metabolite and gene analysis identified the candidate genes involved in these mechanisms, explaining the pattern of biosynthesis and accumulation of these metabolites. CONCLUSIONS: Our findings will contribute to the development of quinoa lines that are low P stress tolerant, thus accelerating the cultivation and industrialization of quinoa.