In particular, water stress associated to high air temperatures and an excess of light during summer, may result in a chronic photo-inhibition or down-regulation of photosynthesis causing a marked decrease in CO2 assimilation (Zhou et al. 2010).
The latter, that include a number of transcription factors – MYB, WRKY, bHLH, salt tolerance proteins, peroxidases, oxygenases and others, could have a major role to adapt tomato plants to day conditions, such as excess of light and higher temperatures.
Plants need protection from the damaging effects of reactive oxygen species generated by the excess of light; in green tissues, carotenoids prevent the chlorophyll-photosensitized formation of highly destructive singlet oxygen by quenching the chlorophyll triplet states, scavenging reactive oxygen species.
despite the excess of light energy.
This results in an excess of light energy whereby electrons accumulate mostly in QA [ 34].
According to Valladares and Pearcy (1998), great differences can be found in overall plant architecture depending on whether they should maximize capture or avoid excess of light.
One of the most common responses of plants to the excess of light to which they are exposed during the LD of the summer is the accumulation of protective pigments derived from the phenylpropanoid biosynthetic pathway.
In some of the species with red-sensitive individuals, lower leaf nitrogen content has been proposed to be involved in the higher vulnerability of anthocyanic plants against excess of light (Kytridis et al. 2008; Nikiforou et al. 2011).
Darwin became interested in plant movements such as orientation towards the sun or the escape from the excess of light provoked or influenced by blue-light, and dedicated a complete volume to them, in which he described the use of a yellow-orange solution of potassium dichromate as a filter to eliminate phototropism (Darwin, 1880).
The cause of this slow assembly is unclear, although it has been reported that an excess of light chain may be required for efficient release of heavy chain from the heat shock protein 70 (HSP70) family chaperone BiP [ 41], and no attempt was made here to optimise the stoichiometry of the components.
