Photon costs of shoot and root NO3-, and root NH4+, assimilation in terrestrial vascular plants considering associated pH regulation, osmotic and ontogenetic effects

John A. Raven (Lead / Corresponding author), Mitchell Andrews

    Research output: Contribution to journalReview articlepeer-review

    1 Citation (Scopus)

    Abstract

    The photon costs of photoreduction/assimilation of nitrate (NO3-) into organic nitrogen in shoots and respiratory driven NO3- and NH4+ assimilation in roots are compared for terrestrial vascular plants, considering associated pH regulation, osmotic and ontogenetic effects. Different mechanisms of neutralisation of the hydroxyl (OH-) ion necessarily generated in shoot NO3- assimilation are considered. Photoreduction/assimilation of NO3- in shoots with malic acid synthesis and either accumulation of malate in leaf vacuoles or transport of malate to roots and catabolism there have a similar cost which is around 35% less than that for root NO3- assimilation and around 20% less than that for photoreduction/assimilation of NO3-, oxalate production and storage of Ca oxalate in leaf vacuoles. The photon cost of root NH4+ assimilation with H+ efflux to the root medium is around 70% less than that of root NO3- assimilation. These differences in photon cost must be considered in the context of the use of a combination of locations of NO3- assimilation and mechanisms of acid-base regulation, and a maximum of 4.9-9.1% of total photon absorption needed for growth and maintenance that is devoted to NO3- assimilation and acid-base regulation.

    Original languageEnglish
    Pages (from-to)127-137
    Number of pages11
    JournalPhotosynthesis Research
    Volume155
    Early online date23 Nov 2022
    DOIs
    Publication statusPublished - Feb 2023

    Keywords

    • Cost benefit analysis
    • Leaf expansion
    • Malate
    • Osmotic potential
    • Photoreduction of nitrate

    ASJC Scopus subject areas

    • Biochemistry
    • Plant Science
    • Cell Biology

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