Journal of Plant Research最新文献

Festuca L. is a perennial plant of the Poaceae family, known for its good palatability and strong tolerance. The characteristics of the chloroplast genomes of six native Festuca species on the Qinghai-Tibet Plateau were analyzed, including four F. sinensis germplasms from Gansu (1), Qinghai (57), Sichuan (111), and Tibet (10-85); F. rubra subsp. arctica; F. kryloviana; F. nitidula; F. valesiaca subsp. sulcata; and F. elata. The chloroplast genome consists of 127 genes, including 4 ribosomal RNA (rRNA) genes, 38 transfer RNA (tRNA) genes, and 83 protein-coding genes. The number of identified SSRs based on 16 shared optimal ciphers of the four F. sinensis germplasms were 48, 50, 49, and 38, respectively, with the majority being single nucleotide repeat sequences. The phylogenetic tree shows that F. nitidula, F. elata, and one germplasm of F. sinensis from Tibet are grouped into the same clade, while three germplasms of F. sinensis from Gansu, Qinghai, and Sichuan are grouped into another clade. F. valesiaca subsp. sulcata, F. ovina, and F. brevipila are grouped into the same clade. F. rubra subsp. arctica and F. rubra are clustered into one branch. This study clarifies the taxonomy of F. sinensis within the genus, providing a reference for subsequent research on the genetic diversity, genetic structure, and phylogeny of Festuca plants.

Cuscuta, a genus of stem-parasitic plants, requires specific light and touch stimuli for host recognition and haustorium formation. Blue and far-red light promote parasitism, while red light inhibits it, but the roles played by light-responsive genes in the early stages of Cuscuta parasitism remain largely unexplored. This study utilized an in vitro C. campestris haustorium induction system to investigate this issue. RNA-sequence analysis revealed a group of differentially expressed genes that responded to the initiation of haustorium formation. Genes associated with light-signaling pathways, including phytochromes (PHYs), phytochrome-interacting factors (PIFs), and homeodomain-leucine zipper I/II transcription factors, were specifically up or downregulated in plants exposed to light for 4 h. Phylogenetic analysis demonstrated that two distinct forms of the PHYB gene, CcPHYB1 and CcPHYB2, were present in all sequenced Cuscuta species. CcPHYB2 was not expressed under normal light conditions, but was specifically upregulated under light regimes inducing haustorium formation; by contrast, CcPHYB1 exhibited non-light-dependent expression. Furthermore, the induction of haustorium formation by far-red light was canceled by red light exposure but could be re-activated by subsequent re-exposure to far-red light. The levels of expression of CcPHYB2, CcPIF1, CcPIF4, CcHOMEOBOX FROM ARABIDOPSIS THALIANA 3 (CcHAT3), CcHOMEOBOX 2 (CcHB2) and CcHB13 varied under different haustorium-inducing light conditions. Expression of these genes altered significantly upon exposure to blue and far-red light, but these changes were reversed in plants exposed to red light. These findings highlight the pivotal role of light-responsive signaling during the early stages of parasitism, providing valuable insights into the molecular mechanisms and evolution of light-mediated host recognition and parasitism in Cuscuta species.

Plants function within complex ecological communities, relying on chemical signals to mediate interactions with other organisms. The foraging behaviour of insects, such as the invasive hornet Vespa velutina nigrithorax, introduced into northwestern Spain over a decade ago, may be influenced by floral volatiles. This hornet detects plant secondary metabolites, including semiochemicals, which aid in locating nectar, carbohydrates, prey, mating sites, and other resources. Understanding the volatile organic compounds (VOCs) emitted by plants visited by V. velutina may help to develop targeted control strategies. The aim of this study was to identify and analyse the volatile compounds emitted by 18 plant species frequented by V. velutina nigrithorax in the province of Ourense, northwest Spain. Solid-phase microextraction (SPME) coupled with gas chromatography-mass spectrometry (GC-MS) was used in this study. A total of 110 VOCs were identified, of which 21 compounds were abundant in the samples, with terpenes being the most abundant. Furthermore, a PLS-DA analysis selected 33 volatile compounds with variable importance scores (VIPs) greater than 1, in particular methylanthranilate with a value of 1.81. Eleven of these compounds were found to be abundant in the analysed samples, including (Z)-β-ocimene; 1-octen-3-ol; 3-hexen-1-ol, acetate, (Z)-; 3-octanone; eugenol; linalool; methyl salicylate; o-cymene; α-farnesene; α-terpineol and β-farnesene. The selection of these compounds provides valuable insights into plant-insect interactions, highlighting their diverse roles as plant volatiles in mediating insect behaviour and underlining their potential as targets for environmentally friendly pest management strategies.

Barley (Hordeum vulgare L.) is an important cereal crop with diverse uses, including animal feed, beer brewing, and food production. Grain size plays a crucial role in determining grain weight and quality, which is one of the key breeding objectives in response to market and industry demands. However, the molecular mechanisms of grain size in barley are still poorly understood. In this study, 250 barley accessions were evaluated for key grain size traits, including thousand grain weight (TGW), grain length (GL), grain width (GW), grain length to width ratio (GLWR), grain area (GA) and grain perimeter (GP) across a two-year period. A total of 369 significant Single Nucleotide Polymorphisms (SNPs) significantly associated with the six grain traits were detected. Among these SNPs, 30 were continuously detected in different years. Additionally, two accessions (ZQ25 and GK5) whose grain size significantly differed were selected for transcriptome analysis. Differentially expressed genes (DEGs) were identified at two time points: 3,733 at 21 days post anthesis (DPA) and 4,396 at 28 DPA. These DEGs were enriched mainly in photosynthesis-antenna proteins, phenylpropanoid biosynthesis and flavonoid biosynthesis. Furthermore, by integrating a genome-wide association study (GWAS) and RNA-seq, we identified 25 candidate genes involved primarily in various transcription factors, phytohormones, and sugar metabolism pathways. These results provide valuable information for grain size-related gene cloning and abundant molecular data for the breeding of new high yield varieties of barley in the future.

Floral glands, which produce diverse metabolites, have become the focus of increasing interest because of their important roles in plant-animal interactions. The glands in the receptacle of Pseudobombax longiflorum (Malvaceae) are widely accepted as nectaries. Using light, scanning, and transmission electron microscopy, we studied the anatomy, histochemistry, ultrastructure, and secretory dynamics of the receptacle glands in this species. The glands were active in secretion from young flower buds to immature fruits. Trigona spinipes was the most abundant and frequent visitor. The glands were composed of a uniseriate epidermis covered with a thick cuticle and a multilayered parenchyma, exhibiting two subregions with abundant phloem in the innermost region. These glands produced sugars, resins, oils, and phenolic compounds. Glandular cells exhibited large nuclei with nucleoli, polymorphic plastids with lipophilic inclusions, numerous mitochondria, endoplasmic reticulum profiles, cytoplasmic oil bodies, and vacuoles containing phenolic compounds. Plasmodesmata indicate that secretory components are transported from cell to cell via the symplast. There is also evidence for granulocrine and eccrine secretion mechanisms. The accumulated secretions form a bulge in the central region of the gland. The bulged epidermis detached from the parenchyma cells, and the rupture of the epidermal cells released the accumulated hydrophilic components. Residual lipophilic secretions were embedded in the epidermal cell wall and cuticle. The receptacle glands of P. longiflorum are not typical nectaries but mixed glands that produce both hydrophilic and lipophilic secretions during floral development until young fruits.

Jasmonate resistant 1 (JAR1), which encodes a jasmonate-amino synthase, mediates the biosynthesis of jasmonoyl-isoleucine (JA-Ile), the bioactive form of jasmonate involved in JA signal transduction pathway. Although JAR1 has been characterized in several plant species, its regulatory function in mediating JA signaling to modulate the biosynthesis of terpenoid indole alkaloids (TIAs) in Catharanthus roseus, a medicinal and ornamental plant, have not been previously investigated. In this study, we have identified and cloned CrJAR1, a member of the Gretchen Hagen3 (GH3) gene family, from C. roseus and confirmed its enzymatic activity in JA-Ile formation via heterologous expression in E. coli. Functional analyses using transient overexpression and virus-induced gene silencing (VIGS) in C. roseus leaves revealed that CrJAR1 positively regulates the accumulation of catharanthine and vindoline. Moreover, we demonstrated that CrCOI1, the jasmonate receptor, functions synergistically with CrJAR1 in modulating TIA biosynthesis. Co-silencing of CrCOI1 and CrJAR1 resulted in a lower sensitivity to exogenous JA treatment compared to silencing of CrJAR1 alone, indicating distinct yet complementary roles in jasmonate-mediated metabolic regulation. These results advance our understanding the function of CrJAR1 and offer new strategies for engineering specialized metabolite biosynthesis in plants.

Anthropogenic climate change is altering precipitation patterns, increasing the length of the dry season and rainfall variability. In this context, the present study aimed to evaluate the influence of drought on the life cycle and reproductive success of the invasive Crotalaria retusa L. (Fabaceae). For this, the seeds were sown in plastic pots containing 3 kg of soil from the collection area. The experiment consisted of 10 treatments with field capacity ranging from 10 to 100%. Germination traits were assessed until seedling emergence and morphological and reproductive parameters were analyzed every 10 days until the end of the reproductive phase, totaling 190 days. Reduced water availability significantly affected plant growth, reducing stem length size, stem diameter and number of leaves at the lowest field capacities evaluated. The reproductive phase was also affected by the low availability of water in the soil. Flowering had a reduction in the number of flower buds and flowers with a reduction in water content. The size and width of the fruits under 50% and 40% field capacity were smaller than in the other treatments. C. retusa is tolerant of low soil water content and can establish itself in field capacities below 30%, but has not produced flowers, fruits, and seeds. The population of the species studied shows a reduction in its growth appears to be resist severe drought and remain in the environment. This may enhance the invasive potential of the species in semi-arid environments.

Compensatory growth of crops is argued to alleviate detrimental parasitic effects. Cuscuta campestris causes severe crop losses worldwide, and is the most important parasitic weed. In a two-year consecutive field investigation, C. campestris was found on Artemisia argyi var. argyi cv. Qiai, one traditional medicinal herb with a long cultivation history in Qizhou, China. In 2020, anatomical validation was conducted on haustorial connection, and competition between carbon (C) and nitrogen (N) in this parasitic system was quantified with isotope signature (δ¹³C, δ¹⁵N) at five sites in 2021. Across sites, leaf senescence of low canopy of infected Qiai was greatly accelerated. Enhancement of resource remobilization from aging leaves (emerging source) mainly supported growth of the parasite (additional sink) also host stem, Qiai successfully abstained intense resource competition with C. campetris, and both species had similar δ¹³C and δ¹⁵N. A new source-sink balance re-established between the parasite and host. Infected Qiai held relatively steady canopy C fixation (constant photosynthetic N use efficiency, biomass and N concentration of green leaves), and branched in top canopy markedly, increasing light access. Together, Qiai appeared to enhance canopy C gain in response to infection. Increase in δ¹³C in this parasite-host association was mild. Finally, this parasite evidently over-stimulated the aboveground biomass of its host, irrespective of infection density and load, and was left behind. This study first reported C. campestris on Qiai, and the latter species execute over-compensation in the field.