Reproductive organ and young tissues show constrained elemental composition in Arabidopsis thaliana

Background and Aims The identification of stoichiometric homeostasis is crucial for understanding plant adaptive strategies under a changing environment. However, current knowledge of plant stoichiometric homeostasis has mainly been obtained from mature leaves, with little from other organs across different developmental stages. Methods We conducted a greenhouse nitrogen (N) and phosphorus (P) addition experiment to evaluate the strength of stoichiometric homeostasis across different organs and developmental stages of Arabidopsis thaliana. Key Results Homeostatic regulation coefficients (H) for N (H-N), P (H-P) and N : P ratio (H-NP) were highest in reproductive tissue, followed by stem and leaf at the same stage. All H parameters in the same organ decreased significantly over the developmental stages. Leaf H-N, H-P and H-NP were highest at stage 1, followed by stages 2 and 3. Both stem and silique at stage 2 relative to stage 3 had higher H-N, H-P and H-NP. These results suggested that reproductive tissue relative to other organs and young tissue relative to old tissue showed more constrained elemental composition in response to nutrient availabilities, and such trends were also evidenced by stoichiometric scaling relationships. Conclusions Our findings highlight that stoichiometric homeostasis is tightly related to the ontogenesis of plant tissue. These results could have a strong implication for diagnosing relative availabilities of N and P in ecosystems, suggesting that the N and P stoichiometry of old tissues might be stronger indicators of nutrient status for plants, but further study is needed to test the generality across species with more distinguishable functional traits