About this Research Topic
Leaves are the main photosynthetic organs in plants and thus they are eminently important for growth and biomass accumulation. Leaves develop from the flanks of shoot apical meristems and after an initial phase of cell proliferation and polarity establishment they enter expansion and maturation phases. Early leaf development involves a massive reprogramming of cellular and physiological characteristics and leads to the formation of chloroplasts from non-green proplastids. Chloroplast function is subsequently maintained for a significant time span during which leaves fix carbon dioxide (CO2) into metabolic intermediates, starch and transportable sugars to serve the growth of other organs with limited or no photosynthetic carbon fixation, including sink leaves, roots or developing flowers. Leaves, as all organs, undergo a process of aging which eventually leads to the execution of an ordered deterioration process – senescence – that normally starts at the leaf tip and progressively moves towards the leaf´s base. During senescence, cellular constituents are destructed and the resulting metabolic breakdown products are transported from the degrading leaf to newly developing organs including seeds. Thus, like photosynthesis itself, senescence supports whole-plant development. Although leaf development is genetically programmed, environmental parameters and abiotic stresses (e.g. drought) have a significant impact as well, and evidence shows that leaves of different ages can be differentially responsive to such stimuli. Reactive oxygen species (ROS) or stress hormones (e.g. ABA) may have important functions in this regard, and cross-talk with growth-regulating hormones such as auxin, gibberellins of brassinosteroids may occur. Transcription factors (TFs) are important regulatory proteins in all organisms and they have been demonstrated to play key roles in virtually all processes that govern leaf development and their responses to stress. However, despite tremendous progress made in the last decade, our understanding of the regulatory integration of TFs with cellular metabolism, signaling and control by epigenetic mechanisms during the different phases of leaf growth remains vague at best in the vast majority of cases. For example, target genes are only known for a relatively small number of TFs, and in only rare occasions have the dynamics of TF-target gene interactions been studied or a cellular resolution of such interactions been analyzed, often due to technical limitations.
This Research Topic is aimed at establishing a wide collection of articles that focus on the different aspects of leaf development, from primordium initiation to senescence, to highlight recent advances in the field. We welcome all types of articles (original research papers, hypotheses, opinions, reviews, modeling approaches, methods) that present new insights into the regulatory networks and cascades underlying leaf development. We are particularly interested in receiving contributions that address the systems integration of gene regulatory with metabolic and signaling networks and consider aspects of leaf aging as well as transients between different leaf growth phases, particularly under conditions of abiotic or nutrient stresses. Articles addressing organelle development and function changes during leaf formation, as well as interactions between them, should also contribute to the Research Topic. We wish to elicit contributions from researchers working on either, dicot or monocot species.
Important Note: All contributions to this Research Topic must be within the scope of the section and journal to which they are submitted, as defined in their mission statements. Frontiers reserves the right to guide an out-of-scope manuscript to a more suitable section or journal at any stage of peer review.