Journal of Plant Research最新文献

Invasion by alien woody plants strongly affects plant-animal interactions, often reducing invertebrate and bird abundance, thereby altering pollination and ultimately influencing plant reproduction. However, it remains unclear whether invasive alien trees also affect interactions typically considered antagonistic, such as nectar robbing. This study investigates the effects of invasive alien trees on insect communities and how these, in turn, affect the occurrence and frequency of nectar robbing in bird-pollinated Erica discolor and Erica unicolor. Floral-visitor observations were recorded at 27 uninvaded and 31 invaded fynbos (a Mediterranean-type shrubland) sites along the southern Cape coastal mountains, South Africa, from April to June 2023. We assessed factors affecting (1) nectar-robbing insect abundance, (2) the rate of nectar robbing, and (3) the impact of nectar robbing on pollination rate. Although overall robbing rates did not differ between invaded and uninvaded sites, the species composition of nectar robbers shifted. The Cape honey bee (Apis mellifera capensis) dominated robbing in uninvaded sites, whereas small solitary bees dominated robbing in invaded sites. Robbing appeared to have no effect on bird pollination rates in either Erica species. This study is the first to directly compare the widely used cumulative measure of robbing rate with observed robbing rate, revealing a significant positive relationship between the two. Together, these findings offer insights into how invasive alien trees can alter fynbos ecosystems and emphasise the critical role of insect communities in shaping plant-animal interactions.

Succulent plants, characterized by the presence of water-storage tissues, often exhibit distinctive leaf morphology. However, their developmental mechanisms remain largely unknown, partly due to the lack of an appropriate model plant. In this study, we evaluated the potential of Asteraceae species as a model system for investigating the mechanisms underlying leaf succulence. First, we analyzed the leaf anatomical and cellular characteristics of succulent plants in the genera Caputia, Crassothonna, Curio, Othonna, and Senecio. To explore a potential mechanism involved in succulent leaf development, we focused on endoreduplication-genome replication without mitosis-and measured the ploidy levels of leaf cells in each species using flow cytometry (FCM) to assess the relationship between leaf succulence and endoreduplication. The FCM data indicated that succulent leaves of Caputia, Curio, Senecio, and Othonna were not associated with endoreduplication. In contrast, endoreduplication was detected in enlarged leaf cells of Crassothonna capensis, while no endoreduplication was observed in the peduncles, which did not appear succulent, or in ligules, which are the lateral organs homologous to leaves. These results suggest that unknown mechanisms other than endoreduplication contribute to leaf succulence in certain genera, and that endoreduplication is regulated in an organ-specific manner in Cr. capensis. Additionally, even if endoreduplication is involved in leaf succulence, it may serve as a supplementary mechanism for cell enlargement. Collectively, these findings highlight Crassothonna and its related genera in Asteraceae as a promising group for studying the mechanisms of leaf succulence.

The facultative parasitic plant Phtheirospermum japonicum forms a specialized organ, the haustorium, to invade its host, Arabidopsis thaliana, establishing a vascular connection via the formation of a xylem bridge. This connection depends on coordinated interactions between the vascular systems of both plants, yet the molecular dynamics of these interactions within the haustorium and the host roots remain elusive. This study aimed to unravel the transcriptomic heterogeneity of haustoria and gene regulatory networks involved in this process by integrating single nucleus RNA sequencing (snRNA-seq) and bulk RNA sequencing (bulk RNA-seq). snRNA-seq identified a total of 7 P. japonicum cell clusters and 4 A. thaliana cell clusters, each with cluster-specific marker genes, allowing for a distinct characterization of vascular cells within the haustorium. Differential gene expression analyses revealed up-regulation of genes associated with xylem formation and auxin transport in both parasites and hosts, suggesting the presence of shared molecular mechanisms facilitating vascular connection. Further gene network analysis combining snRNA-seq and bulk RNA-seq identified conserved homologous genes across both species, indicating potential molecular interactions of vascular-related genes from hosts and parasites. Our study reveals the high heterogeneity of haustorium cells, characterizing the expression profiles of each cell type in haustoria and host roots during haustorium development at single-cell resolution. These findings provide insights into the molecular interactions between parasitic plants and hosts, presenting potential targets for disrupting these interactions to manage parasitic plant infestations in crops.

Nanopriming is a crucial advancement in boosting seed germination, growth, and stress tolerance under abiotic stress conditions such as salinity, drought, and extreme temperatures. This technique employs nanoparticles (NPs) to trigger specific metabolic processes that enhance germination and overall plant vigour while strengthening plant defenses against environmental challenges. Research indicates that NPs, including multi-walled carbon nanotubes and metal-based NPs, significantly influence plant physiological responses. This enhancement in plant resilience is achieved through activating antioxidant defenses and reducing reactive oxygen species. Moreover, nanopriming promotes uniform seed germination, boosts plant growth, and improves tolerance to abiotic stresses by stimulating secondary metabolite production and enhancing water uptake. This is accomplished by upregulating genes related to water transport proteins like aquaporins and stress-responsive pathways, which improve water dynamics and metabolic activities critical for early plant development. Recent transcriptomic studies have confirmed that nanoprimed seeds show increased gene expression linked to stress management and growth regulation. This review explores the effects of nanopriming on seed germination, plant growth, and how it modifies molecular mechanisms to mitigate abiotic stresses, while emphasizing the potential of integrating green synthesis for NP production. Such integration aligns with sustainable agricultural practices, minimizing environmental impact and enhancing crop yields under stressful conditions. Future research aims to refine NP formulations for greater efficacy and safety, incorporating advanced technologies such as artificial intelligence to further optimize nanopriming for agricultural applications.

Biodiversity status assessments are typically conducted on a regional basis. Consequently, there are numerous species that are rare in one region but ubiquitously present in another country or administrative region. Correctly assessing the conservation status and value of such "endangered species" is essential to achieve better biodiversity conservation through the appropriate and efficient use of socioeconomic resources. A comparative genomic analysis was conducted on Torenia concolor, which is widely distributed in Southeast and East Asia, but has a limited population in Japan, specifically on Amami Oshima Island. This population has not yet been established as a conservation priority due to the possibility that it may have originated from cultivated plants. We hypothesized that the population was not due to a human-induced distribution; indeed, our findings indicate that the Amami Oshima population is derived from a natural distribution and is phylogenetically unique, retaining comparable genetic diversity with more abundant populations and exhibiting no increase in deleterious variations in their genome. These findings highlight the unique conservation significance of the Amami Oshima population. Furthermore, the findings suggest that this population, being genetically robust, may be sustainably conserved through minimal intervention strategies, such as maintaining current habitat conditions and monitoring population size, as the accumulation of deleterious mutations is comparable to that of the Taiwanese population. This study highlights the importance of accurate assessment of genomic status and contributes to a broader understanding of conservation strategies for regionally rare species.

Local adaptation is a central evolutionary process for creating/maintaining variation of traits mediating antagonistic interactions. However, few studies have evaluated the local adaptation of plants to their biological counterparts such as herbivores across the plants' distribution. Most studies evaluating local adaptation to herbivores have focused on specialist systems, where local adaptation is likely to occur. However, there is less evidence regarding the existence of local adaptation on generalist systems, where local adaptation is not theoretically expected. We conducted a reciprocal transplant experiment involving four local populations aimed to detect whether local adaptation in the annual herb Datura stramonium to its specialist herbivore Lema daturaphila and the generalist herbivore Sphenarium purpurascens occur. We also explored whether leaf trichome density, a putative defensive trait of D. stramonium, is mediating local adaptation to herbivores through its association with plant fitness. We found that certain D. stramonium populations were locally adapted to both herbivores but others were not, regardless of whether these are preyed upon by generalist or specialist herbivores. Leaf trichome density had a significant effect on individual fruit production, although this effect was variable across locations (origin × site interaction) and unrelated to the observed local adaptation pattern. The results support a view of a local adaptation mosaic of D. stramonium to generalist and specialist herbivores in central Mexico.

Cutting-induced adventitious root (AR) formation is crucial for vegetative propagation, a key method that produces plants identical to parent. However, many woody plants pose challenges for vegetative propagation due to difficulties in AR formation. Hormones play important roles during AR formation, with auxin serving as the key regulator and interacting with other hormones. In this review, we summarize the molecular events and hormone functions involved in AR formation in woody plants. A deeper understanding of these processes could enhance the design and manipulation of techniques to improve vegetative propagation in woody plants, ultimately leading to greater economic benefits.

Gamma-aminobutyric acid (GABA) is a metabolite involved in plant growth and stress responses, with its synthesis regulated by glutamate decarboxylase (GAD). Plant GAD enzymes have an autoinhibitory α-helix at the C-terminus, which calmodulin (CaM) binding typically relieves. Eliminating this C-terminal motif usually increases GABA levels in crops. In this case study, we generated a CRISPR/Cas9-edited lettuce line with a 14-amino acid deletion in the C-terminal helix of LsGAD2, the isozyme primarily expressed in most tissues. This targeted truncation removes CaM-binding residues while retaining the key Lys cluster (Lys489, Lys490, Lys491) responsible for autoinhibition, resulting in a significant reduction in GABA content without affecting growth. The LsGAD1/2-ΔC line showed a transcriptomic profile resembling stress responses in the wildtype under unstressed conditions. Reduced GABA levels appeared to upregulate genes involved in stress perception, signalling, and defense-related metabolic and hormonal changes, potentially mediated by WRKY-family transcription factors. Likely due to lower GABA levels and altered defense responses, LsGAD1/2-ΔC plants showed increased Agrobacterium-mediated transient expression of β-glucuronidase. Overall, our study suggests that targeted genetic manipulation of the C-terminal helix of GAD enzymes can reduce GABA levels while enhancing transformation efficiency in lettuce, thus presenting a means for engineering for such purposes.

Interspecific hybrids with different genomes from their parents often result in hybrid sterility due to meiotic failure. This is a typical example of reproductive isolation that limits interspecific hybridization. Although a few progenies can be obtained in such cases, the inheritance pattern of fertility has not yet been studied in detail. Therefore, using Nicotiana as a model, the fertility of hybrids derived from crosses between species with different genomes was investigated up to the F₃ generation. In the F₂ population, which developed from selfing seeds obtained from the low-fertility F₁ generation, extremely large variation in pollen viability (1.2-82.9%, average 43.2%), fruit set rate (0-100%, average 69.3%), and seed number (16-185, average 63.5) were observed among individuals. In addition, some of the F₃ individuals from F₂ individuals with low fertility were high-fertility. Furthermore, it was suggested that not only pollen viability, but also pistil length and number of ovules may be involved in the variation in fertility. Genome-wide genotyping using GRAS-Di technology revealed that the genomes of high-fertility F₂ individuals had fewer heterozygous genomic regions, leading to a hypothesis regarding the association between the proportion of heterozygous regions in the genome and pollen viability. To our knowledge, this study represents the first experimental observation that high-fertility F₂ individuals can be obtained from interspecific F₁ hybrids carrying different genomes with extremely low fertility without change of ploidy. These findings can be considered basic insights that enhance our understanding of plant speciation and adaptation.