Journal of Experimental Botany最新文献

Geophytic plants synchronize growth and quiescence with the external environment to survive and thrive under changing seasons. Together with seasonal growth adaptation, dormancy and sprouting are critical factors determining crop yield and market supply, as various geophytes also serve as major food, floriculture, and ornamental crops. Dormancy in such crops determines crop availability in the market, as most of them are consumed during the dormant stage. On the other hand, uniform/maximal sprouting is crucial for maximum yield. Thus, dormancy and sprouting regulation have great economic importance. Dormancy-sprouting cycles in geophytes are regulated by genetic, exogenous (environmental), and endogenous (genetic, metabolic, hormonal, etc.) factors. Comparatively, the temperature is more dominant in regulating dormancy and sprouting in geophytes, unlike above-ground tissues, where both photoperiod and temperature control are involved. Despite huge economic importance, studies concerning the regulation of dormancy and sprouting are scarce in the majority of geophytes. To date, only a few molecular factors involved in the process have been suggested. Recently, omics studies on molecular and metabolic factors involved in dormancy and growth regulation of underground vegetative tissues have provided more insight into the mechanism. Here, we discuss current knowledge of the environmental and molecular regulation and control of dormancy and sprouting in geophytes, and discuss challenges/questions that need to be addressed in the future for crop improvement.

Bud dormancy is a survival strategy that plants have developed in their native habitats. It helps them endure harsh seasonal changes by temporarily halting growth and activity until conditions become more favorable. Research has primarily focused on bud dormancy in tree species and the ability to halt growth in vegetative tissues, particularly in meristems. Various plant species, such as potato, have developed specialized storage organs, enabling them to become dormant during their yearly growth cycle. Deciduous trees and potato tubers exhibit a similar type of bud endodormancy, where the bud meristem will not initiate growth, even under favorable environmental conditions. Chilling accumulation activates C-repeat/dehydration responsive element binding (DREB) factors (CBFs) transcription factors that modify the expression of dormancy-associated genes. Chilling conditions shorten the duration of endodormancy by influencing plant hormones and sugar metabolism, which affect the timing and rate of bud growth. Sugar metabolism and signaling pathways can interact with abscisic acid, affecting the symplastic connection of dormant buds. This review explores how chilling affects endodormancy duration and explores the similarity of the chilling response of dormant buds in potato tubers and woody perennials.

Plants have evolved specific temperature preferences, and shifts above this range cause heat stress with detrimental effects such as physiological disruptions, metabolic imbalances, and growth arrest. To reduce damage, plants utilize the heat shock response (HSR), signaling cascades that activate the heat shock factors (HSFs), transcription factors that control the heat stress-responsive transcriptome for activation of protective measures. While the core HSR is well-studied, we still know relatively little about heat stress perception and signal integration or cross-talk with other pathways. In the last few years, however, significant progress has been made in this area, which is summarized here. It has emerged that the plant hormones brassinosteroids (BRs) and abscisic acid (ABA) contribute to heat stress tolerance by impacting HSF modes of activity. Also, we began to understand that heat stress is sensed in different cellular compartments and that events in the nucleus, such as nuclear condensate formation via liquid-liquid phase separation, play a key role. In the future, it will be important to explore how these multilayered perception and signaling modes are utilized to understand how environmental context and developmental stage determine the outcome of heat stress effects on plant growth and development.

To ensure their vital role in disseminating the species, dormant seeds have developed adaptive strategies to protect themselves against pathogens and predators. This is orchestrated through the synthesis of an array of constitutive defences that are put in place in a developmentally regulated manner, which are the focus of this review. We summarize the defence activity and the nature of the molecules coming from the exudate of imbibing seeds that leak into their vicinity, also referred to as the spermosphere. As a second layer of protection, the dual role of the seed coat will be discussed; as a physical barrier and a multi-layered reservoir of defence compounds that are synthesized during seed development. Since imbibed dormant seeds can persist in the soil for extensive periods, we address the question of whether during this time a constitutively regulated defence programme is switched on to provide further protection, via the well-defined pathogenesis-related (PR) protein family. In addition, we review the hormonal and signalling pathways that might be involved in the interplay between dormancy and defence and point out questions that need further attention.

Plants synchronize their growth and development with environmental changes, which is critical for their survival. Among their life cycle transitions, seed germination is key for ensuring the survival and optimal growth of the next generation. However, even under favorable conditions, often germination can be blocked by seed dormancy, a regulatory multilayered checkpoint integrating internal and external signals. Intricate genetic and epigenetic mechanisms underlie seed dormancy establishment, maintenance, and release. In this review, we focus on recent advances that shed light on the complex mechanisms associated with physiological dormancy, prevalent in seed plants, with Arabidopsis thaliana serving as a model. Here, we summarize the role of multiple epigenetic regulators, but with a focus on histone modifications such as acetylation and methylation, that finely tune dormancy responses and influence dormancy-associated gene expression. Understanding these mechanisms can lead to a better understanding of seed biology in general, as well as resulting in the identification of possible targets for breeding climate-resilient plants.

The succulent plant syndrome is defined by the coordination of traits that enhance internal water storage within plant tissues. Although distributed globally in different habitats, succulent plants are thought to have evolved to avoid drought in arid regions, due to trait modifications that decrease tissue water deficits. We evaluated the evolution and the ecological significance of the succulent strategy at a global scale by comparing the climatic niche of species displaying succulence within the Core Caryophyllales with their non-succulent relatives. We assembled and curated a worldwide dataset of 201K georeferenced records belonging to 5447 species within 28 families, and analyzed the climatic niche of species along with their origin and evolutionary trajectories using ecological niche modeling, phylogenetic regression, divergence dates and ancestral state estimation. Results indicate the Core Caryophyllales have inhabited drylands since their origin in the Early Cretaceous. However, the succulent syndrome appeared and diversified during later geologic periods. The climatic niche space of succulents is narrower than non-succulent relatives, but no climate niche separation was detected between groups. Our results support alternative interpretations on the environmental and ecological forces that spurred the origin and diversification of the succulent plant syndrome and the radiation of rich succulent lineages.

Winter dormancy is a key process in the phenology of temperate perennials. Climate change is severely impacting its course leading to economic losses in agriculture. A better understanding of the underlying mechanisms, as well as the genetic basis of the different responses, is necessary for the development of climate-resilient cultivars. This study aims to provide an insight into winter dormancy in red raspberry (Rubus idaeus L). We report the transcriptomic profiles during dormancy in two raspberry cultivars with contrasting responses. The cultivar 'Glen Ample' showed a typical perennial phenology, whereas 'Glen Dee' registered consistent dormancy dysregulation, exhibiting active growth and flowering out of season. RNA-seq combined with weighted gene co-expression network analysis identified gene clusters in both genotypes that exhibited time-dependent expression profiles. Functional analysis of 'Glen Ample' gene clusters highlighted the significance of the cell and structural development prior to dormancy entry as well the role of genetic and epigenetic processes such as RNAi and DNA methylation in regulating gene expression. Dormancy release in 'Glen Ample' was associated with up-regulation of transcripts associated with the resumption of metabolism, nucleic acid biogenesis, and processing signal response pathways. Many of the processes occurring in 'Glen Ample' were dysregulated in 'Glen Dee' and 28 transcripts exhibiting time-dependent expression in 'Glen Ample' that also had an Arabidopsis homologue were not found in 'Glen Dee'. These included a gene with homology to Arabidopsis VRN1 (RiVRN1.1) that exhibited a sharp decline in expression following dormancy induction in 'Glen Ample'. Characterization of the gene region in the 'Glen Dee' genome revealed two large insertions upstream of the ATG start codon. We propose that expression below detection level of a specific VRN1 homologue in 'Glen Dee' causes dormancy misregulation as a result of inappropriate expression of a subset of genes that are directly or indirectly regulated by RiVRN1.1.