Responses of flavonoids to solar UV radiation and gradual soil drying in two Medicago truncatula accessions
2023
Rai, Neha | Neugart, Susanne | Schröter, David | Lindfors, Anders V. | Aphalo, Pedro J. | Ilmatieteen laitos | Finnish Meteorological Institute | 0000-0001-9305-0864
Ground level UV-B (290–315 nm) and UV-A (315–400 nm) radiation regulates multiple aspects of plant growth and development. In a natural environment, UV radiation interacts in a complex manner with other environmental factors (e.g., drought) to regulate plants’ morphology, physiology, and growth. To assess the interactive efects of UV radiation and soil drying on plants’ secondary metabolites and transcript abundance, we performed a feld experiment using two diferent accessions of Medicago truncatula (F83005-5 French origin and Jemalong A17 Australian origin). Plants were grown for 37 days under long-pass flters to assess the efects of UV short wavelength (290–350 nm, UVsw) and UV-A long wavelength (350–400 nm, UV-Alw). Soil–water defcit was induced by not watering half of the plants during the last seven days of the experiment. The two accessions difered in the concentration of favonoids in the leaf epidermis and in the whole leaf: F83005-5 had higher concentration than Jemalong A17. They also difered in the composition of the favonoids: a greater number of apigenin derivatives than tricin derivatives in Jemalong A17 and the opposite in F83005-5. Furthermore, UVsw and soil drying interacted positively to regulate the biosynthesis of favonoids in Jemalong A17 through an increase in transcript abundance of CHALCONE SYNTHASE (CHS). However, in F83005-5, this enhanced CHS transcript abundance was not detected. Taken together the observed metabolite and gene transcript responses suggest diferences in mechanisms for acclimation and stress tolerance between the accessions.
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