Integration of C/N-nutrient and multiple environmental signals into the ABA signaling cascade

Signalling and regulation of plant development by carbon/nitrogen balance

The two most abundant macronutrients in plant cells are carbon (C) and nitrogen (N). Coordination of their cellular metabolism is a fundamental factor in guaranteeing the optimal growth and development of plants. N availability and assimilation profoundly affect plant gene expression and modulate root and stem architecture, thus affecting whole plant growth and crop yield. N status also affects C fixation, as it is an important component of the photosynthetic machinery in leaves. Reciprocally, increasing C supply promotes N uptake and assimilation. There is extensive knowledge of the different mechanisms that plants use for sensing and signalling their nutritional status to regulate the assimilation, metabolism and transport of C and N. However, the crosstalk between C and N pathways has received much less attention. Plant growth and development are greatly affected by suboptimal C/N balance, which can arise from nutrient deficiencies or/and environmental cues. Mechanisms that integrate and respond to changes in this specific nutritional balance have started to arise. This review will examine the specific responses to C/N imbalance in plants by focusing on the main inorganic and organic metabolites involved, how they are sensed and transported, and the interconnection between the early signalling components and hormonal networks that underlies plants' adaptive responses.

Drought Tolerance in Plants: Physiological and Molecular Responses

Drought, a significant environmental challenge, presents a substantial risk to worldwide agriculture and the security of food supplies. In response, plants can perceive stimuli from their environment and activate defense pathways via various modulating networks to cope with stress. Drought tolerance, a multifaceted attribute, can be dissected into distinct contributing mechanisms and factors. Osmotic stress, dehydration stress, dysfunction of plasma and endosome membranes, loss of cellular turgidity, inhibition of metabolite synthesis, cellular energy depletion, impaired chloroplast function, and oxidative stress are among the most critical consequences of drought on plant cells. Understanding the intricate interplay of these physiological and molecular responses provides insights into the adaptive strategies plants employ to navigate through drought stress. Plant cells express various mechanisms to withstand and reverse the cellular effects of drought stress. These mechanisms include osmotic adjustment to preserve cellular turgor, synthesis of protective proteins like dehydrins, and triggering antioxidant systems to counterbalance oxidative stress. A better understanding of drought tolerance is crucial for devising specific methods to improve crop resilience and promote sustainable agricultural practices in environments with limited water resources. This review explores the physiological and molecular responses employed by plants to address the challenges of drought stress.

Recent Advances in Carbon and Nitrogen Metabolism in C3 Plants

C and N are the most important essential elements constituting organic compounds in plants. The shoots and roots depend on each other by exchanging C and N through the xylem and phloem transport systems. Complex mechanisms regulate C and N metabolism to optimize plant growth, agricultural crop production, and maintenance of the agroecosystem. In this paper, we cover the recent advances in understanding C and N metabolism, regulation, and transport in plants, as well as their underlying molecular mechanisms. Special emphasis is given to the mechanisms of starch metabolism in plastids and the changes in responses to environmental stress that were previously overlooked, since these changes provide an essential store of C that fuels plant metabolism and growth. We present general insights into the system biology approaches that have expanded our understanding of core biological questions related to C and N metabolism. Finally, this review synthesizes recent advances in our understanding of the trade-off concept that links C and N status to the plant's response to microorganisms.

Borage extracts affect wild rocket quality and influence nitrate and carbon metabolism

Market is increasingly demanding vegetables with high quality and nutraceutical characteristics. It was demonstrated that leafy vegetables can get benefit from biostimulants, for the reduction of nitrate concentration and the increment of antioxidants, with potential benefit for human health. The research purpose was to investigate on the role of a novel plant-based biostimulant in affecting nitrogen and carbon metabolism in wild rocket (Diplotaxis tenuifolia L.). Foliar spray treatments were performed with extracts obtained from borage (Borago officinalis L.) leaves and flowers. To evaluate the treatments effect, in vivo determinations (chlorophyll a fluorescence and chlorophyll content) were performed. At harvest, nitrate concentration, sucrose, total sugars, chlorophyll, and carotenoids levels were measured in leaves. In order to characterize the mechanism of action also at molecular level, a set of genes encoding for some of the key enzymes implicated in nitrate and carbon metabolism was selected and their expression was measured by qRT-PCR. Interesting results concerned the increment of sucrose, coherent with a high value of Fv/Fm, in addition to a significant reduction of nitrate and ABA than control, and an enhanced NR in vivo activity. Also, genes expression was influenced by extracts, with a more pronounced effect on N related genes.