Photosynthetic Induction Under Fluctuating Light Is Affected by Leaf Nitrogen Content in Tomato.

Hu Sun,Yu-Qi Zhang,Wei Huang,Shi-Bao Zhang

doi:10.3389/fpls.2022.835571

Abstract

The response of photosynthetic CO2 assimilation to changes of illumination affects plant growth and crop productivity under natural fluctuating light conditions. However, the effects of nitrogen (N) supply on photosynthetic physiology after transition from low to high light are seldom studied. To elucidate this, we measured gas exchange and chlorophyll fluorescence under fluctuating light in tomato (Solanum lycopersicum) seedlings grown with different N conditions. After transition from low to high light, the induction speeds of net CO2 assimilation (AN), stomatal conductance (gs), and mesophyll conductance (gm) delayed with the decline in leaf N content. The time to reach 90% of maximum AN, gs and gm was negatively correlated with leaf N content. This delayed photosynthetic induction in plants grown under low N concentration was mainly caused by the slow induction response of gm rather than that of gs. Furthermore, the photosynthetic induction upon transfer from low to high light was hardly limited by photosynthetic electron flow. These results indicate that decreased leaf N content declines carbon gain under fluctuating light in tomato. Increasing the induction kinetics of gm has the potential to enhance the carbon gain of field crops grown in infertile soil.

Highlights

Plants capture light energy to produce chemical energy ATP and NADPH, which are used to drive nitrogen assimilation and the conversion of CO2 to sugar
An important explanation for this is that leaf photosynthetic capacity is related to the leaf N content in many higher plants (Yamori et al, 2011; Fan et al, 2020; Li et al, 2020), since stromal enzymes and thylakoid proteins account for Photosynthesis Under Fluctuating Light the majority of leaf N (Makino and Osmond, 1991; Sudo et al, 2003; Takashima et al, 2004)
Altering gm kinetics would significantly influence assimilation rate (AN) upon transfer from low to high light, at least in tomato. These results suggested that the photosynthetic limitation upon transfer from low to high light was largely different from the photosynthetic induction during illumination of dark-adapted leaves

Summary

Introduction

Plants capture light energy to produce chemical energy ATP and NADPH, which are used to drive nitrogen assimilation and the conversion of CO2 to sugar. Many previous studies indicated that increasing AN under constant high light can boost plant biomass (Kebeish et al, 2007; Timm et al, 2012, 2015). Altering the photosynthetic performance under dynamic illumination is a promising way to improve photosynthesis under natural fluctuating light (FL) conditions. Plants grown under high nitrogen (N) concentration usually have higher biomass than plants grown under low N concertation (Makino, 2011). An important explanation for this is that leaf photosynthetic capacity is related to the leaf N content in many higher plants (Yamori et al, 2011; Fan et al, 2020; Li et al, 2020), since stromal enzymes and thylakoid proteins account for Photosynthesis Under Fluctuating Light the majority of leaf N (Makino and Osmond, 1991; Sudo et al, 2003; Takashima et al, 2004). Few is known about the effects of leaf N content on non-steady-state photosynthetic performances under FL

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