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Summary A dynamic assembly of nuclear and cytoplasmic processes regulate gene activity. Hypoxic stress and the associated energy crisis activate a plurality of regulatory mechanisms including modulation of chromatin structure, transcriptional activation and post‐transcriptional processes. Temporal control of genes is associated with specific chromatin modifications and transcription factors. Genome‐scale technologies that resolve transcript subpopulations in the nucleus and cytoplasm indicate post‐transcriptional processes enable cells to conserve energy, prepare for prolonged stress and accelerate recovery. Moreover, the harboring of gene transcripts associated with growth in the nucleus and macromolecular RNA–protein complexes contributes to the preferential translation of stress‐responsive gene transcripts during hypoxia. We discuss evidence of evolutionary variation in integration of nuclear and cytoplasmic processes that may contribute to variations in flooding resilience. 

Summary Understanding the impact of elevated CO₂(eCO₂) in global agriculture is important given climate change projections. Breeding climate‐resilient crops depends on genetic variation within naturally varying populations. The effect of genetic variation in response to eCO₂is poorly understood, especially in crop species. We describe the different ways in whichSolanum lycopersicumand its wild relativeS. pennelliirespond to eCO₂, from cell anatomy, to the transcriptome, and metabolome. We further validate the importance of translational regulation as a potential mechanism for plants to adaptively respond to rising levels of atmospheric CO₂. 

Plant roots integrate environmental signals with development using exquisite spatiotemporal control. This is apparent in the deposition of suberin, an apoplastic diffusion barrier, which regulates flow of water, solutes and gases, and is environmentally plastic. Suberin is considered a hallmark of endodermal differentiation but is absent in the tomato endodermis. Instead, suberin is present in the exodermis, a cell type that is absent in the model organismArabidopsis thaliana. Here we demonstrate that the suberin regulatory network has the same parts driving suberin production in the tomato exodermis and theArabidopsisendodermis. Despite this co-option of network components, the network has undergone rewiring to drive distinct spatial expression and with distinct contributions of specific genes. Functional genetic analyses of the tomato MYB92 transcription factor and ASFT enzyme demonstrate the importance of exodermal suberin for a plant water-deficit response and that the exodermal barrier serves an equivalent function to that of the endodermis and can act in its place. 

Comparative transcriptomics has emerged as a powerful approach that allows us to unravel the genetic basis of organ morphogenesis and its diversification processes during evolution. However, the application of comparative transcriptomics in studying plant morphological diversity addresses challenges such as identifying homologous gene pairs, selecting appropriate developmental stages for comparison, and extracting biologically meaningful networks. Methods such as phylostratigraphy, clustering, and gene co-expression networks are explored to identify functionally equivalent genes, align developmental stages, and uncover gene regulatory relationships. In the current review, we highlight the importance of these approaches in overcoming the complexity of plant genomes, the impact of heterochrony on stage alignment, and the integration of gene networks with additional data for a comprehensive understanding of morphological evolution. 

The basic unit of chromatin, the nucleosome, is an octamer of four core histone proteins (H2A, H2B, H3, and H4) and serves as a fundamental regulatory unit in all DNA-templated processes. The majority of nucleosome assembly occurs during DNA replication when these core histones are produced en masse to accommodate the nascent genome. In addition, there are a number of nonallelic sequence variants of H2A and H3 in particular, known as histone variants, that can be incorporated into nucleosomes in a targeted and replication-independent manner. By virtue of their sequence divergence from the replication-coupled histones, these histone variants can impart unique properties onto the nucleosomes they occupy and thereby influence transcription and epigenetic states, DNA repair, chromosome segregation, and other nuclear processes in ways that profoundly affect plant biology. In this review, we discuss the evolutionary origins of these variants in plants, their known roles in chromatin, and their impacts on plant development and stress responses. We focus on the individual and combined roles of histone variants in transcriptional regulation within euchromatic and heterochromatic genome regions. Finally, we highlight gaps in our understanding of plant variants at the molecular, cellular, and organismal levels, and we propose new directions for study in the field of plant histone variants.