Expression of LHC genes and their relation to photooxidative stress tolerance in Solanum lycopersicum L. and Solanum chilense (Dunal) Reiche

Javier Chilian1*, Isabel Verdugo1, Fernando Poblete1, Simón Ruiz-Lara1, José A. Casaretto1, and Enrique González1

Simultaneous exposition to low temperature and high light radiation cause photoinhibition of photosynthetic apparatus, affecting the productivity and geographical distribution of agricultural crops. In several Solanaceous species, tolerance to low temperature stress in combination with high light has been associated with some stimulation in non-photochemical quenching (NPQ), which involved reorganization in light-harvesting complex (LHC) proteins. To study photosynthetic performance in Solanum lycopersicum L. and S. chilense (Dunal) Reiche, and to investigate transcriptional regulation of genes encoding LHC proteins and their involvement in the NPQ, plants of both species were exposed to low temperature (4 °C) and high light radiation (1300 µmol m-2 s-1). Lipid peroxidation, photochemical efficiency, and changes in xanthophyll cycle pigments were measured. The results presented here indicate that S. chilense showed higher tolerance to photoinhibition than S. lycopersicum under low-temperature and high light conditions, increasing light-energy consumption in photochemical processes by increasing photosynthetic capacity as indicated by photochemical quenching (qP) and relative electron transport rate (ETR) parameters. The contribution of light-harvesting chlorophyll a/b binding (LHC) protein was not related to dissipate excess excitation energy as heat (NPQ), but rather with the antioxidant function attributable to zeaxanthin as indicated by the amount of peroxidized lipids in S. chilense. We suggest that the differential expression of Lhca1 transcripts, with zeaxanthin binding sites could contribute to the greater tolerance of S. chilense to photoxidative stress.

Keywords: Lipid-peroxidation, photoinhibition, photochemical quenching, zeaxanthin.
1Universidad de Talca, Instituto de Biología Vegetal y Biotecnología, 2 Norte Nº 685, Talca, Chile. *Corresponding author (jchilian@inia.cl).