The Dynamic Plant: Capture, Transformation, and Management of Energy

Abstract

Plants are exquisite in their capacity to convert photons of light through photosynthetic carbon dioxide (CO 2 ) fixation into carbohydrate resources that are assimilated and partitioned from photosynthetic source to sink tissues. The chemical energy gained from photosynthesis includes ATP and NADPH that along with sugars are vital to biosynthetic processes, cell proliferation, biomass production, and reproductive fitness. As in all eukaryotes, plants are dependent upon dioxygen (O 2 ) for efficient production of ATP through aerobic respiration by mitochondria. Therefore, O 2 is crucial for the efficient catabolism of carbohydrates, lipids, and protein into chemical energy in leaves in the light and darkness, as well as in sink tissues. In this Focus Issue, numerous reviews and research articles explore the integration of light, O 2 , and energy metabolism from the cellular to the whole-plant level. The articles analyze molecular, biochemical, physiological, and developmental mechanisms that contribute to the plant's energy balance. A recurrent theme is the integration of light, O 2 , and sugar sensing with signal transduction and gene regulation, resulting in metabolic and developmental plasticity that maximizes available energy for growth. This knowledge expands opportunities to enhance photosynthetic efficiency and finetune energy allocation to maximize yields of crops.

Dissecting Hierarchies between Light, Sugar and Auxin Action Underpinning Root and Root Hair Growth

“…Furthermore, the establishment of root traits are also modulated by signals obtained from above ground signals [ 3 ]. Root length depends highly on the meristem activity of the root, which is regulated by various signaling cascades integrating environmental signals and availability of resources [ 1 , 8 ]. The D-root system prevents direct illumination of the root and thereby reduces stress responses in the root tip and this results in a higher proliferation rate, the total root length is longer in DGR [ 1 , 21 ].…”

“…The root consists of a meristematic zone that continually delivers new cells, and its activity arrests when the environmental conditions are not beneficial for the plant. After leaving the division zone, cells pass through the transition and elongation zone towards the differentiation zone, whereby they are maturing and primed according to the growth conditions of the root and the shoot, which are connected through signaling cascades with each other [ 5 , 6 , 7 , 8 ]. Root length is defined by the balance between cell proliferation and cell elongation [ 1 , 4 ].…”

“…Plant growth’s plasticity, especially the proliferation rate, depends significantly on carbohydrates gained over photosynthesis [ 8 , 9 ]. However, depending on the wavelength, light is also triggering fast-growth processes over asymmetric auxin distribution to change cell elongation behavior [ 3 ] and the root is negatively phototropic, which results in growth away from the light source [ 1 , 3 ].…”

Maintaining homeostasis by controlled alternatives for energy distribution in plant cells under changing conditions of supply and demand

“…The role of GapC in improving biomass production by redirecting energy fluxes according to the light and nutrient availability requires analysis of mechanisms at multiple regulatory levels. To improve productivity by increasing the efficiency of photosynthesis, the aspect of adaptation and the required signals and time span to realize an altered machinery for flexible responses need to be taken into consideration (Foyer et al 2017b ; Bailey-Serres et al 2018 ). It is crucial to obtain a better understanding of the interaction of the various mechanisms that help to fine-tune the responses of plant cells to changing environments, when aiming for “better plants” to be created by biotechnological approaches (Kramer and Evans 2011 ; Kerchev et al 2015 ).…”

Distinct Responses to Light in Plants

“…The use of light during photosynthesis is achieved through two photosystems present in the chloroplast’s photosynthetic pigments, which show a narrow pick absorption range of the solar spectrum despite pigments absorbed throughout the photosynthetically active radiation (PAR) spectrum. Unlike the light regulation mediated by photoreceptor genes present in the nucleus and responsible for physiological responses such as germination, flowering, circadian clock input, and dormancy, photosynthesis requires a coordinated regulation of the nuclear and plastidic genomes [ 9 ]. In the chloroplast, photons of light are converted into glucose molecules in a two-step reaction pathway.…”