Journal of Experimental Botany最新文献

Precise regulation of reproductive growth is vital for plant reproductive success and resource management. Here, we characterize Growth Regulating Factor 9 (NnGRF9), an atypical 14-3-3 family protein in lotus (Nelumbo nucifera), and demonstrate its positive role in shade-induced flower bud abortion. Overexpression of NnGRF9 increases, while silencing reduces, bud abortion, with evidence suggesting that NnGRF9 promotes autophagy during this process. We further identified a reciprocal regulatory loop between NnGRF9 and the energy sensor kinase NnSnRK1, in which NnGRF9 promotes NnSnRK1 expression and activity, whereas NnSnRK1 interacts with NnGRF9 and may regulate its stability. Functional hierarchy analysis places NnGRF9 upstream of NnSnRK1 in regulating both bud abortion and autophagy. NnSnRK1 directly interacts with NnATG6, but not with NnATG1, and manipulation of NnATG6 expression demonstrates that it functions downstream in the regulation of both autophagy and bud abortion. Population genetic analysis reveals that NnGRF9 has been subject to positive selection during lotus evolution, with its allelic variation correlating with differences in flowering abundance among cultivars. In summary, this study elucidates an NnGRF9-NnSnRK1-NnATG6 regulatory pathway that connects shade stress to reproductive fate, and provides population genetic evidence for its role in lotus adaptation and domestication.

Flowering marks a pivotal transition in a plant's life cycle, signalling the shift from vegetative growth to reproductive development. Over the years, extensive research has uncovered key genes and regulatory networks governing this process. Central to this regulation is the Florigen Activation Complex (FAC), along with its interacting partners and upstream and downstream components, which have been well-characterized across numerous plant species. More recently, attention has turned to a lesser-known gene, FLOWERING PROMOTING FACTOR 1 (FPF1). Initially identified in Arabidopsis thaliana, FPF1 is a plant-specific gene lacking known functional domains, yet it plays a conserved and critical role in floral induction across diverse species. Despite its discovery in 1997, the molecular mechanism of FPF1 remained elusive until recent studies began to unravel the function of FPF and its homologs. One such study revealed that FPF1-Like Protein 1 (FLP1) in Arabidopsis is expressed in phloem companion cells sites of FLOWERING LOCUS T (FT) production. Like AtFT, AtFLP1 acts as a mobile florigenic signal, though it operates independently of the canonical AtFT pathway. AtFLP1 promotes flowering by activating the floral homeotic gene SEP3, suggesting an alternative regulatory route also influenced by photoperiod. Interestingly, studies in Brachypodium distachyon have highlighted a contrasting role for FLP-like genes, where they negatively regulate flowering by interfering with the FAC, underscoring species-specific diversity in its function. While initial studies have been majorly focused on their role in flowering, in recent years FPF1 family genes have also been implicated in other developmental processes, including stem and root elongation and shade avoidance responses. In this review, we explore these emerging insights into FPF1-like proteins, examining their multifaceted roles in flowering regulation and broader developmental functions, with a special emphasis on the most recent and impactful studies.

The co-evolutionary arms race between crops and their parasites requires continuous identification of new resistance mechanisms. Broomrape (Orobanche cumana), a root parasitic plant, poses a severe threat to sunflower (Helianthus annuus) production, yet the genetic architecture underlying host resistance remains poorly understood. To address this, we established a high-throughput phenotyping platform to quantify root infestation across a diverse sunflower association mapping (SAM) population. Combining this phenotypic resource with a dual genome-wide association study (GWAS) strategy based on both single nucleotide polymorphisms (SNPs) and k-mers, we highlight the genetic basis of broomrape resistance at unprecedented resolution. Our analyses revealed quantitative trait loci (QTLs) and identified novel candidate genes, including putative leucine-rich repeat receptor kinases potentially involved in parasite recognition and defense activation. Importantly, the k-mer approach circumvented reference genome bias and uncovered key genomic introgressions from wild Helianthus relatives that contribute substantially to resistance. These findings demonstrate the utility of integrating high-resolution phenotyping with advanced association mapping to dissect complex host-parasite interactions. Moreover, they emphasize the enduring value of wild germplasm as a reservoir of adaptive variation, providing crop breeders with crucial tools to counter the rapid evolutionary dynamics of parasitic plants.

The functions of approximately one-third of the proteins in the model plant Arabidopsis thaliana remain unknown. It is likely that some of the genes encoding these proteins are essential, and thus indispensable for the survival of the plant; furthermore, these genes would be included in the minimum viable set required for plant life. Evolutionarily conserved single copy genes in flowering plants are enriched in essential housekeeping functions. Building on this observation, we designed a reverse genetic screen that focuses on evolutionarily conserved single copy Arabidopsis genes of unknown function with predominant expression in meristematic cells. This approach identified a previously uncharacterized essential Arabidopsis gene, named as EARLY ABORTION 1 (EBO1). Mutation of the EBO1 locus disrupts gametophyte and/or early embryo development, resulting in defective ovule or seed development. A functional fluorescent EBO1 fusion protein was found to localize to the nucleus, and co-immunoprecipitation experiments detected an interaction between EBO1 and Nucleolar Protein 58 (NOP58) and proteins involved in RNA metabolism, chromatin modification, and transcription. The presented results open a new line of investigation into an evolutionarily conserved mechanism involved in the development of both male and female gametophytes as well as seeds.

Present in various subcellular compartments, cysteine is the major source of reduced sulfur and thus represents a key metabolite for various biosynthetic pathways as well as for redox homeostasis as a component of glutathione. As photosynthetic organisms assimilate inorganic sulfate and reduce it into sulfide before its incorporation into cysteine, there are strong relationships between cysteine homeostasis and all pathways involved in its synthesis and utilization. Over the last decade, cysteine degradation leading to hydrogen sulfide release has been linked to different physiological responses to both abiotic and biotic stresses. In this review, we summarize current knowledge about cysteine homeostasis, cysteine signaling in immunity and cysteine-dependent sulfur trafficking. We also illustrate the importance of cysteine signaling through the synthesis of hydrogen sulfide by describing the diversity of cysteine desulfhydrases in photosynthetic organisms and by discussing their roles in plant physiology.

Vitamin B1 is a vital cofactor in cellular metabolism, but must be obtained through the diet in humans. Polished (white) rice, a dietary staple for much of the global population, contains very low levels of vitamin B1, which contributes to widespread thiamin deficiency in regions that rely heavily on rice. To address this issue, we engineered rice to express the Saccharomyces cerevisiae thiamin transporter gene THI7 under the control of the endosperm-specific GLUTELIN1 (GT1) promoter. We found that endosperm-specific expression of yeast THI7 significantly increased thiamin levels by up to 24% in unpolished and 26% in polished seeds in transgenic rice lines with moderate to high THI7 expression. This increase was specific to free thiamin, with no change in thiamin monophosphate or thiamin diphosphate, consistent with the known transporter activity of THI7. Importantly, the transgenic plants displayed normal phenotypes under field conditions. Our findings demonstrate that endosperm-targeted expression of a heterologous thiamin transporter is an effective strategy for enhancing vitamin B1 content in rice grains, offering a new approach for biofortification that complements metabolic engineering of biosynthetic pathways.

Although orchid pollination is often highly specialized, fully mycoheterotrophic orchids are generally thought to favor autonomous self-pollination because of carbon limitation, shaded habitats, and patchy population structure. Here, we investigated six nectarless, fully mycoheterotrophic Gastrodia species in Japan using long-term pollinator observations and hand-pollination experiments, together with phylogenomic analyses of all six species, floral scent analyses of three species, and larval rearing experiments in four species. All six species were self-compatible but incapable of autonomous selfing and relied on drosophilid flies for pollination. Pollinator assemblage dissimilarity was significantly correlated with interspecific genetic differentiation, indicating phylogenetically structured pollinator use. Fruit-feeding drosophilids pollinated all species, whereas mycophagous drosophilids contributed substantially to pollination only in G. foetida and G. nipponica. In these two species, larvae frequently developed in decaying floral tissues, consistent with brood-site mutualism. In G. confusa and G. pubilabiata, larval survival was sporadic and humidity dependent, indicating an intermediate condition between brood-site deception and mutualism. Floral scents of three representative species were dominated by fermentation-related volatiles, but blend composition differed among species. Together, these findings reveal a deception-mutualism continuum within Gastrodia and suggest that evolutionary history, together with floral scent variation, helps shape pollinator interactions in these orchids.

Plant cuticular waxes form a critical hydrophobic barrier covering aerial organs, serving as the first line of defense against abiotic and biotic stresses and playing a vital role in reproductive development. However, regulatory networks that orchestrate cuticular wax deposition in response to environmental cues and developmental programs, particularly in cereal crops, remain elusive. This review integrates current knowledge by identifying genes implicated in wax formation in Arabidopsis and major graminaceous crops. We detail the molecular mechanisms of wax biosynthesis and export, and place a major focus on the intricate transcriptional regulatory modules that integrate signals from drought, salinity, and pathogens, as well as developmental signals critical for anther cuticle formation and male fertility. Conserved and species-specific adaptations in these networks are highlighted, emphasizing how natural variation in these pathways underpins adaptive traits. We also discuss evolutionary perspectives and critically identify key knowledge gaps, such as the unresolved trade-offs between abiotic and biotic stress resistance and the mechanistic basis of anther cuticle development under heat stress, providing insights into leveraging cuticular traits for climate-resilient crop design.

Hypoxia is integral to the plant life cycle, occurring during both development and environmental stresses like flooding. The class I phytoglobins (PGB1s) have emerged as important regulators of plant hypoxia responses in both these contexts due to their multifaceted roles in nitric oxide (NO) and ROS homeostasis, and alternative energy generation. Physiological PGB1 expression overlaps with developmental hypoxic niches, facilitating hypoxic energy generation through the PGB1-NO cycle. Sustained induction of PGB1 by various signals during the progression of a flooding event reflects its important but potentially distinct roles in flooding stress acclimation. These include short-term PGB1-mediated NO scavenging to stabilize ERF-VII TFs, and in the long-term hypoxic energy generation, oxidative stress mitigation, and maintenance of auxin transport. Here we provide an overview of the current understanding of how PGB1 biochemistry, localization, and regulatory architecture are connected and of relevance for hypoxia acclimation. We highlight key unanswered questions in our understanding of PGB1 biology that will be essential for clarifying its contribution to hypoxia acclimation and plant environmental resilience.

Alternative splicing (AS) has emerged as a regulatory layer in plant adaptation to the environment. In particular, biotic stresses trigger a drastic remodeling of the plant AS landscape, with minimal overlap with changes at the gene expression level, suggesting an additional, albeit poorly understood, mechanism of regulation. Recent studies have revealed that effectors from unrelated pathogens target core spliceosome components as well as accessory splicing factors. While this targeting is beginning to shed light on the relevance of the modulation of the plant AS landscape for pathogen invasion, it has also led to the identification of novel splicing factors, allowing the discovery of unexplored characteristics of the plant splicing machinery. Here, we review this emerging field, which delineates an additional battleground in the evolutionary arms race between plants and pathogens and has the potential to advance our biochemical and mechanistic understanding of the plant spliceosomal complex.