The colonization of land by plants marked a pivotal transformation in terrestrial ecosystems. In order to adapt to the terrestrial environment, angiosperms, which dominate the terrestrial flora with around 300,000 species, have evolved sophisticated mechanisms for sexual reproduction involving intricate interactions between male and female structures, starting from pollen deposition on the stigma and culminating in double fertilization within the ovule. The pollen tube plays a crucial role by navigating through female tissues to deliver sperm cells. The molecular intricacies of these male-female interactions, involving numerous signaling pathways and regulatory proteins, have been extensively studied over the past two decades. This review summarizes recent findings on the regulatory mechanisms of these male-female interactions in angiosperms. We aim to provide a comprehensive understanding of plant reproductive biology and highlight the implications of these mechanisms for crop improvement and the development of new agricultural technologies.

Plant nitrogen nutrition is an essential and energy-costly component of terrestrial food chains. Understanding nitrate sensing in plants can lead to improved crop yields and nutrient use efficiency, directly impacting food security and agricultural sustainability. Herein, we review and present a comprehensive framework for understanding nitrate sensing in plants, integrating molecular, genetic, and physiological aspects. We begin by detailing the primary nitrate response and nitrate starvation response, which are central to the plant's ability to sense and respond to nitrate availability. We then explore the intricate interactions between nitrate signaling and other nutritional pathways such as those for carbon, phosphorus, potassium, and sulfur assimilation and reactive oxygen species (ROS) handling, and how it unfolds in long-distance systemic communication between roots and shoots. Finally, evolutionary insights are provided by comparing nitrate-sensing mechanisms across different plant species as well as Bacteria, Archaea, Chlorophyta, Charophyta (algae), and Fungi, revealing how these mechanisms may have evolved in diverse ecological niches. This review not only provides a framework to project our present and future understanding of plant nitrate and nitrogen nutrition but also offers potential strategies for improving nutrient use efficiency in crops through genetic and biotechnological interventions.

Biodiversity conservation requires conserving evolutionary potential-the capacity for wild populations to adapt. Understanding genetic diversity and evolutionary dynamics is critical for informing conservation decisions that enhance adaptability and persistence under environmental change. We review how emerging landscape genomic methods provide plant conservation programs with insights into evolutionary dynamics, including local adaptation and its environmental drivers. Landscape genomic approaches that explore relationships between genomic variation and environments complement rather than replace established population genomic and common garden approaches for assessing adaptive phenotypic variation, population structure, gene flow, and demography. Collectively, these approaches inform conservation actions, including genetic rescue, maladaptation prediction, and assisted gene flow. The greatest on-the-ground impacts from such studies will be realized when conservation practitioners are actively engaged in research and monitoring. Understanding the evolutionary dynamics shaping the genetic diversity of wild plant populations will inform plant conservation decisions that enhance the adaptability and persistence of species in an uncertain future.

The shoot meristem of land plants maintains the capacity for organ generation throughout its lifespan due to a group of undifferentiated stem cells. Most meristems are shaped like a dome with a precise spatial arrangement of functional domains, and, within and between these domains, cells interact through a network of interconnected signaling pathways. Intercellular communication in meristems is mediated by mobile transcription factors, small RNAs, hormones, and secreted peptides that are perceived by membrane-localized receptors. In recent years, we have gained deeper insight into the underlying molecular processes of the shoot meristem, and we discuss here how plants integrate internal and external inputs to control shoot meristem activities.

Since the discovery of the first ribonucleic acid (RNA) modifications in transfer RNAs (tRNAs) and ribosomal RNAs (rRNAs), scientists have been on a quest to decipher the identities and functions of RNA modifications in biological systems. The last decade has seen monumental growth in the number of studies that have characterized and assessed the functionalities of RNA modifications in the field of plant biology. Owing to these studies, we now categorize RNA modifications based on their chemical nature and the RNA on which they are found, as well as the array of proteins that are involved in the processes that add, read, and remove them from an RNA molecule. Beyond their identity, another key piece of the puzzle is the functional significance of the various types of RNA modifications. Here, we shed light on recent studies that help establish our current understanding of the diversity of RNA modifications found in plant transcriptomes and the functions they play at both the molecular (e.g., RNA stability, translation, and transport) and organismal (e.g., stress response and development) levels. Finally, we consider the key research questions related to plant gene expression and biology in general and highlight developments in various technologies that are driving our insights forward in this research area. Expected final online publication date for the Annual Review of Plant Biology, Volume 74 is May 2023. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Recurring patterns are an integral part of life on Earth. Through evolution or breeding, plants have acquired systems that coordinate with the cyclic patterns driven by Earth's movement through space. The biosystem responses to these physical rhythms result in biological cycles of daily and seasonal activity that feed back into the physical cycles. Signaling networks to coordinate growth and molecular activities with these persistent cycles have been integrated into plant biochemistry. The plant circadian clock is the coordinator of this complex, multiscale, temporal schedule. However, we have detailed knowledge of the circadian clock components and functions in only a few species under controlled conditions. We are just beginning to understand how the clock functions in real-world conditions. This review examines what we know about the circadian clock in diverse plant species, the challenges with extrapolating data from controlled environments, and the need to anticipate how plants will respond to climate change.

Despite the numerous advances made in our understanding of the physiology and molecular genetics of salinity tolerance, there have been relatively few applications of these to improve the salt tolerance of crops. The most significant advances have historically utilized intraspecific variation, introgression of traits from close crop wild relatives, or, less frequently, introgression from more distant relatives. Advanced lines often fail due to difficulties in the introgression or tracking of traits or due to yield penalties associated with the alleles in nonsaline environments. However, the greatest limitation is that salinity is not a primary trait for breeders. We must close the gap between research and delivery, especially for farmers who have precious few alternatives. These efforts should include a reassessment of old techniques such as grafting current crops with salt-tolerant hybrid rootstocks. Alternatively, future crops can be produced via domestication of salt-tolerant wild species-an approach that is now feasible in our lifetime. Expected final online publication date for the Annual Review of Plant Biology, Volume 74 is May 2023. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Plant invasions, a byproduct of globalization, are increasing worldwide. Because of their ecological and economic impacts, considerable efforts have been made to understand and predict the success of non-native plants. Numerous frameworks, hypotheses, and theories have been advanced to conceptualize the interactions of multiple drivers and context dependence of invasion success with the aim of achieving robust explanations with predictive power. We review these efforts from a community-level perspective rather than a biogeographical one, focusing on terrestrial systems, and explore the roles of intrinsic plant properties in determining species invasiveness, as well as the effects of biotic and abiotic conditions in mediating ecosystem invasibility (or resistance) and ecological and evolutionary processes. We also consider the fundamental influences of human-induced changes at scales ranging from local to global in triggering, promoting, and sustaining plant invasions and discuss how these changes could alter future invasion trajectories.

cis-Regulatory elements encode the genomic blueprints that ensure the proper spatiotemporal patterning of gene expression necessary for appropriate development and responses to the environment. Accumulating evidence implicates changes to gene expression as a major source of phenotypic novelty in eukaryotes, including acute phenotypes such as disease and cancer in mammals. Moreover, genetic and epigenetic variation affecting cis-regulatory sequences over longer evolutionary timescales has become a recurring theme in studies of morphological divergence and local adaptation. Here, we discuss the functions of and methods used to identify various classes of cis-regulatory elements, as well as their role in plant development and response to the environment. We highlight opportunities to exploit cis-regulatory variants underlying plant development and environmental responses for crop improvement efforts. Although a comprehensive understanding of cis-regulatory mechanisms in plants has lagged behind that in animals, we showcase several breakthrough findings that have profoundly influenced plant biology and shaped the overall understanding of transcriptional regulation in eukaryotes.

Similar traits and functions commonly evolve in nature. Here, we explore patterns of replicated evolution across the plant kingdom and discuss the processes responsible for such patterns. We begin this review by defining replicated evolution and the theoretical, genetic, and ecological concepts that help explain it. We then focus our attention on empirical cases of replicated evolution at the phenotypic and genotypic levels. We find that replication at the ecotype level is common, but evidence for repeated ecological speciation is surprisingly sparse. On the other hand, the replicated evolution of ecological strategies and physiological mechanisms across similar biomes appears to be pervasive. We conclude by highlighting where future efforts can help us bridge the understanding of replicated evolution across different levels of biological organization. Earth's landscape is diverse but also repeats itself. Organisms seem to have followed suit.