Photosynthetic control of electron transport and the regulation of gene expression

Abstract

The term 'photosynthetic control' describes the short- and long-term mechanisms that regulate reactions in the photosynthetic electron transport (PET) chain so that the rate of production of ATP and NADPH is coordinated with the rate of their utilization in metabolism. At low irradiances these mechanisms serve to optimize light use efficiency, while at high irradiances they operate to dissipate excess excitation energy as heat. Similarly, the production of ATP and NADPH in ratios tailored to meet demand is finely tuned by a sophisticated series of controls that prevents the accumulation of high NAD(P)H/NAD(P) ratios and ATP/ADP ratios that would lead to potentially harmful over-reduction and inactivation of PET chain components. In recent years, photosynthetic control has also been extrapolated to the regulation of gene expression because mechanisms that are identical or similar to those that serve to regulate electron flow through the PET chain also coordinate the regulated expression of genes encoding photosynthetic proteins. This requires coordinated gene expression in the chloroplasts, mitochondria, and nuclei, involving complex networks of forward and retrograde signalling pathways. Photosynthetic control operates to control photosynthetic gene expression in response to environmental and metabolic changes. Mining literature data on transcriptome profiles of C(3) and C(4) leaves from plants grown under high atmospheric carbon dioxide (CO(2)) levels compared with those grown with ambient CO(2) reveals that the transition to higher photorespiratory conditions in C(3) plants enhances the expression of genes associated with cyclic electron flow pathways in Arabidopsis thaliana, consistent with the higher ATP requirement (relative to NADPH) of photorespiration.

Response of linear and cyclic electron flux to moderate high temperature and high light stress in tomato

“…Foyer et al (2012) supported the idea that to cope with high irradiance, the thylakoid membranes were more flexible and in dynamic change. Arabidopsis thaliana plants grown in HH showed an increased amount of PSII units and a typically lower ratio of chlorophyll a/chlorophyll b (Bailey et al, 2004;Zivcak et al, 2014).…”

Long‐term acclimation to reciprocal light conditions suggests depth‐related selection in the marine foundation speciesPosidonia oceanica

“…The key enzyme in the carbon fixation processes, the RuBisCO (Foyer, Neukermans, Queval, Noctor, & Harbinson, 2012) shows no changes in the shallow plants. Moreover, contrarily to expectations, deep plants that would need to increase RuBisCO efficiency and carbon uptake under high light (Lambers, Chapin, & Pons, 2008) showed a trend toward its down‐regulation from T1 to T3.…”

Geração e desintoxicação enzimática de espécies reativas de oxigênio em plantas

“…Nessas organelas, as cadeias transportadoras de elétrons (CTE) não são apenas a força motriz do metabolismo celular, mas geradoras de sinais redox, que participam e regulam processos biológicos das plantas, mediante a formação de ROS (FOYER & NOCTOR, 2003 de elétrons. Apesar de geração de uma ROS, esse fl uxo de elétrons evita que moléculas da CTE da fotossíntese mantenham-se em estado reduzido e produz sinais oxidativos que regulam a expressão gênica (FOYER & NOCTOR, 2009;FOYER et al, 2012). A geração do O 2…”