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.
