Light Spectral Composition Influences Structural and Eco-Physiological Traits of Solanum lycopersicum L. cv. ‘Microtom’ in Response to High-LET Ionizing Radiation

Palma Simoniello,Veronica De Micco,Luca Vitale,Carmen Arena,Tsonko Tsonev,Violeta Velikova,Giulia Costanzo,Ermenegilda Vitale

doi:10.3390/plants10081752

Abstract

This study evaluated if specific light quality (LQ) regimes (white fluorescent, FL; full-spectrum, FS; red-blue, RB) during plant growth modified morphological and photosynthetic traits of Solanum lycopersicum L. ‘Microtom’ plants irradiated at the dry seed stage with 25 Gy 48Ca ions (IR). The irradiation reduced plant size while it increased leaf dry matter content (LDMC) and relative water content (RWC) compared to the control. FS and RB light regimes determined a decrease of plant height and a rise of RWC compared to FL plants. The irradiation under FS and RB regimes favoured the development of dwarf plants and improved the leaf water status. Under the FL regime, irradiated plants showed reduced photosynthesis and stomatal conductance. The opposite behavior was observed in RB irradiated plants in which gas exchanges were significantly stimulated. RB regime enhanced Rubisco expression in irradiated plants also inducing anatomical and functional adjustments (i.e., increase of leaf thickness and incidence of intercellular spaces). Finally, 48Ca ions did not prevent fruit ripening and the achievement of the ‘seed-to seed’ cycle, irrespective of the LQ regime. Overall, the present study evidenced that RB light regime was the most effective in optimising growth and photosynthetic efficiency of ‘Microtom’ irradiated plants. These outcomes may help to develop proper cultivation protocols for the growth of dwarf tomato in Controlled Ecological Life Support Systems (CELSS).

Highlights

The cultivation of crops in controlled conditions guarantees food production throughout the year, overcoming the limitations of environmental constraints
This study evaluated if specific light quality (LQ) regimes during plant growth modified morphological and photosynthetic traits of Solanum lycopersicum L
This study showed that the interplay between ionizing radiation (Ca-heavy ions) and light quality regimes elicits specific structural and ecophysiological responses in ‘Microtom’ plants irradiated at the dry seed target stage, which should be taken into account when designing the cultivation protocols for this species in BLSSs in Space

Summary

Introduction

The cultivation of crops in controlled conditions guarantees food production throughout the year, overcoming the limitations of environmental constraints. The use of light-emitting diodes (LEDs) technology allowed us to create suitable light environments for indoor cultivation by selecting specific wavelengths able to elicit plant-exclusive photomorphogenic, biochemical or physiological responses [1,2,3]. The manipulation of the light spectrum is a widely applied methodology to improve plant photosynthesis and secondary metabolite production, including bioactive compounds beneficial for human health. The B wavelength perceived through cryptochromes controls many processes such as stem elongation, phototropism, chloroplast movement within cells, stomatal opening, and elicits the biosynthesis of secondary metabolites such as flavonoids [5,6]. The R light contributes to photosynthetic apparatus development and influences morphogenesis

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Conclusion