Current Opinion in Plant Biology

Lateral root (LR) formation in Arabidopsis is a continuous, repetitive, post-embryonic process regulated by a series of coordinated events and tuned by the environment. It shapes the root system, enabling plants to efficiently explore soil resources and adapt to changing environmental conditions. Although the auxin-regulated modules responsible for LR morphogenesis and emergence are well documented, less is known about the initial priming. Priming is characterised by recurring peaks of auxin signalling, which, once memorised, earmark cells to form the new LR...

Plants use programmed cell death as a potent defense response against biotrophic pathogens that require living host cells to thrive. However, cell death can promote infection by necrotrophic pathogens. This discrepancy creates specific co-evolutionary dynamics in the interaction between plants and necrotrophs. Necrotrophic pathogens produce diverse cell death-inducing effectors that act redundantly on several plant targets and sometimes suppress plant immune responses as an additional function. Plants use surface receptors that recognize necrotrophic effectors to increase quantitative disease resistance, some of which evolved independently in several plant lineages...

No abstract text is available yet for this article.

Plants have evolved diverse strategies to meet their nutritional needs. Parasitic plants employ haustoria, specialized structures that facilitate invasion of host plants and nutrient acquisition. Legumes have adapted to nitrogen-limited conditions by developing nodules that accommodate nitrogen-fixing rhizobia. The formation of both haustoria and nodules is induced by signals originating from the interacting organisms, namely host plants and rhizobial bacteria, respectively. Emerging studies showed that both organogenesis crucially involves plant hormones such as auxin, cytokinins, and ethylene and also integrate nutrient availability, particularly nitrogen...

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...

The emergence of plant hormone signaling pathways is deeply intertwined with land plant evolution. In angiosperms, two plant hormones, salicylic Acid (SA) and Jasmonates (JAs), play a key role in plant defense, where JAs-mediated defenses are typically activated in response to herbivores and necrotrophic pathogens, whereas SA is prioritized against hemi/biotrophic pathogens. Thus, studying the evolution of SA and JAs and their crosstalk is essential to understand the evolution of molecular plant-microbe interactions (EvoMPMI) in land plants...

In the unending coevolutionary dance between plants and microbes, each player impacts the evolution of the other. Here, we provide an overview of the burgeoning field of evolutionary molecular plant-microbe interactions (EVO-MPMI)-the study of mechanisms of plant-microbe interactions in the context of their evolutionary history-tracing its progression from foundational science to practical implementation. We present a snapshot of current research and delve into central concepts, such as conserved features and convergent evolution, as well as methodologies such as ancestral reconstruction...

No abstract text is available yet for this article.

How organs acquire their shapes is a central question in developmental biology. In plants, aerial lateral organs such as leaves initiate at the flanks of the growing meristem as dome-shaped primordia. These simple structures then grow out along multiple polarity axes to achieve a dizzying array of final shapes. Many of the hormone signaling pathways and genetic interactions that influence growth along these axes have been identified in the past few decades. Open questions include how and when initial gene expression patterns are set in organ primordia, and how these patterns are translated into the physical outcomes observed at the cellular and tissue levels...

The vascular system was essential for plants to colonize land by facilitating the transport of water, nutrients, and minerals throughout the body. Our current knowledge on the molecular-genetic control of vascular tissue specification and differentiation is mostly based on studies in the Arabidopsis primary root. To what degree these regulatory mechanisms in the root meristem can be extrapolated to vascular tissue development in other organs is a question of great interest. In this review, we discuss the most recent progress on cotyledon vein formation, with a focus on polar auxin transport-dependent and -independent mechanisms...

Mutualistic interactions between plants and microorganisms shape the continuous evolution and adaptation of plants such as to the terrestrial environment that was a founding event of subsequent life on land. Such interactions also play a central role in the natural and agricultural ecosystems and are of primary importance for a sustainable future. To boost plant's productivity and resistance to biotic and abiotic stresses, new approaches involving associated symbiotic organisms have recently been explored. New discoveries on mutualistic symbioses evolution and the interaction between partners will be key steps to enhance plant potential...

C4 photosynthesis is more efficient than C3 photosynthesis for two reasons. First, C4 plants have evolved efficient C4 enzymes to suppress wasteful photorespiration and enhance CO2 fixation. Second, C4 leaves have Kranz anatomy in which the veins are surrounded by one layer of bundle sheath (BS) cells and one layer of mesophyll (M) cells. The BS and M cells are functionally well differentiated and also well coordinated for rapid assimilation of atmospheric CO2 and transport of photo-assimilates between the two types of cells...

Plant specialized metabolites shape plant interactions with the environment including plant-microbe interactions. While we often group compounds into generic classes, it is the precise structure of a compound that creates a specific role in plant-microbe or-pathogen interactions. Critically, the structure guides definitive targets in individual interactions, yet single compounds are not limited to singular mechanistic targets allowing them to influence interactions across broad ranges of attackers, from bacteria to fungi to animals...

Plants are able to actively detect and respond to the presence in neighboring plants, in order to optimize their physiology to promote survival and reproduction despite the presence of competing organisms. A key but still poorly understood mechanism for neighbor detection is through the perception of root exudates. In this review, we explore recent findings on the role of root exudates in plant-plant interactions, focusing both on general interactions and also the highly specialized example of root parasite-host plant interactions...

Hormones played a fundamental role in improvement of yield in cereal grasses. Natural variants affecting gibberellic acid (GA) and auxin pathways were used to breed semi-dwarf varieties of rice, wheat, and sorghum, during the "Green Revolution" in the 20th century. Since then, variants with altered GA and cytokinin homeostasis have been used to breed cereals with increased grain number. These yield improvements were enabled by hormonal regulation of intercalary and inflorescence meristems. Recent advances have highlighted additional pathways, beyond the traditional CLAVATA-WUSCHEL pathway, in the regulation of auxin and cytokinin in inflorescence meristems, and have expanded our understanding of the role of GA in intercalary meristems...

A communication system between plant cells and their surrounding cell wall is required to coordinate development, immunity, and the integration of environmental cues. This communication network is facilitated by a large pool of membrane- and cell-wall-anchored proteins that can potentially interact with the matrix or its fragments, promoting cell wall patterning or eliciting cellular responses that may lead to changes in the architecture and chemistry of the wall. A mechanistic understanding of how these receptors and cell wall proteins recognize and interact with cell wall epitopes would be key to a better understanding of all plant processes that require cell wall remodeling such as expansion, morphogenesis, and defense responses...

Plants have evolved robust adaptive mechanisms to withstand the ever-changing environment. Tightly regulated distribution of the hormone auxin throughout the plant body controls an impressive variety of developmental processes that tailor plant growth and morphology to environmental conditions. The proper flow and directionality of auxin between cells is mainly governed by asymmetrically localized efflux carriers - PINs - ensuring proper coordination of developmental processes in plants. Discerning the molecular players and cellular dynamics involved in the establishment and maintenance of PINs in specific membrane domains, as well as their ability to readjust in response to abiotic stressors is essential for understanding how plants balance adaptability and stability...

Plant cells possess the ability to dedifferentiate and reprogram into stem cell-like populations, enabling the regeneration of new organs. However, the maintenance of stem cells relies on specialized microenvironments composed of distinct cell populations with specific functions. Consequently, the regeneration process necessitates the orchestrated regulation of multiple pathways across diverse cellular populations. One crucial pathway involves the transcription factor WUSCHEL HOMEOBOX 5 (WOX5), which plays a pivotal role in reprogramming cells into stem cells and promoting their conversion into shoot meristems through WUSCHEL (WUS)...

In the stomatal lineage, repeated arcs of initiation, stem-cell proliferation, and terminal cell fate commitment are displayed on the surface of aerial organs. Over the past two decades, the core transcription and signaling elements that guide cell divisions, patterning, and fate transitions were defined. Here we highlight recent work that extends the core using a variety of cutting-edge techniques in different plant species. New work has discovered transcriptional circuits that initiate and reinforce stomatal fate transitions, while also enabling the lineage to interpret and respond to environmental inputs...

Land plants (embryophytes), including vascular (tracheophytes) and non-vascular plants (bryophytes), co-evolved with microorganisms since descendants of an algal ancestor colonized terrestrial habitats around 500 million years ago. To cope with microbial pathogen infections, embryophytes evolved a complex immune system for pathogen perception and activation of defenses. With the growing number of sequenced genomes and transcriptome datasets from algae, bryophytes, tracheophytes, and available plant models, comparative analyses are increasing our understanding of the evolution of molecular mechanisms underpinning immune responses in different plant lineages...