Plant Cell Reports最新文献

Key message: We developed an in-house Python-based image analysis pipeline to investigate the movement patterns of Cuscuta. Our analysis unveiled that the coiling and circumnutation movements of Cuscuta are regulated by its intrinsic circadian rhythm. Cuscuta spp., commonly known as dodders, are rootless and leafless stem parasitic plants. Upon germination, Cuscuta starts rotating immediately in a counterclockwise direction (circumnutation) to locate a host plant, creating a seamless vascular connection to steal water and nutrients from its host. In this study, our aim was to elucidate the dynamics of the coiling patterns of Cuscuta, which is an essential step for successful parasitism. Using time-lapse photography, we recorded the circumnutation and coiling movements of C. campestris at different inoculation times on non-living hosts. Subsequent image analyses were facilitated through an in-house Python-based image processing pipeline to detect coiling locations, angles, initiation and completion times, and duration of coiling stages in between. The study revealed that the coiling efficacy of C. campestris varied with the inoculation time of day, showing higher success and faster initiation in morning than in evening. These observations suggest that Cuscuta, despite lacking leaves and a developed chloroplast, can discern photoperiod changes, significantly determining its parasitic efficiency. The automated image analysis results confirmed the reliability of our Python pipeline by aligning closely with manual annotations. This study provides significant insights into the parasitic strategies of C. campestris and demonstrates the potential of integrating computational image analysis in plant biology for exploring complex plant behaviors. Furthermore, this method provides an efficient tool for investigating plant movement dynamics, laying the foundation for future studies on mitigating the economic impacts of parasitic plants.

Key message: OsCactinpositively regulates drought tolerance in rice. OsCactin is regulated by OsTRAB1 and interacts with OsDi19 proteins to defend against drought stress. Drought stress significantly limits plant growth and production. Cactin, a CactinC_cactus domain-containing protein encoded by a highly conserved single-copy gene prevalent across the eukaryotic kingdom, is known to play diverse roles in fundamental biological processes. However, its function in rice drought tolerance remains poorly understood. In this study, with its overexpression and knockout rice lines in both a pot drought experiment and a PEG drought-simulation test, OsCactin was found to positively regulate rice drought tolerance during the rice seedling stage. The OsCactin-overexpressing lines presented high tolerance to drought stress, whereas the OsCactin-knockout plants were sensitive to drought stress. OsCactin was localized in the nucleus, and was predominantly expressed in the leaves and panicles at the seedling and booting stages, respectively. Furthermore, OsTRAB1, a drought-responsive TF of the bZIP family, binds to the promoter of OsCactin as a drought-responsive regulator. OsDi19 proteins, the Cys2/His2 (C2H2)-type zinc finger TFs from the drought-induced 19 family, interact with OsCactin both in vitro and in vivo. Our results provide new insights into the intricate mechanisms by which OsCactin regulates the rice drought stress response, which may contribute to the design of molecular breeding methods for rice.

Key message: MT mitigates chilling damage by enhancing antioxidant system and photosystem activities, and cold-responsive genes expression in cucumbers. H₂O₂ may act as a downstream signaling molecule in the MT-induced chilling tolerance. Melatonin (MT) and hydrogen peroxide (H₂O₂) are important endogenous signaling molecules that play multifaceted roles in plant responses to abiotic stress. However, the interactive mechanism by which MT and H₂O₂ regulate chilling tolerance remains unclear. Here we found that MT exhibited a positive regulatory effect on the chilling tolerance of cucumbers, with an optimum concentration of 100 µM. MT markedly enhanced RBOH1 mRNA expression, activity and endogenous H₂O₂ accumulation in cucumber seedlings. However, 1.0 mM H₂O₂ had no significant effect on mRNA levels of TDC and ASMT, the key genes for MT synthesis, and endogenous MT content. Both MT and H₂O₂ significantly decreased malondialdehyde (MDA), electrolyte leakage (EL) and chilling injury index (CI) by activating the antioxidant system, thereby alleviating chilling damage in cucumber seedlings. MT and H₂O₂ improved photosynthetic carbon assimilation, which was primarily attributed to an increase in activity, mRNA expression, and protein levels of RuBPCase and RCA. Meanwhile, MT and H₂O₂ induced the photoprotection for both PSII and PSI by enhancing the QA's electron transport capacity and elevating protein levels of the photosystems. Moreover, MT and H₂O₂ significantly upregulated the expression of cold response genes. MT-induced chilling tolerance was attenuated by N', N'-dimethylthiourea (DMTU), a H₂O₂ specific scavenger. Whereas, the MT synthesis inhibitor (p-chlorophenylalanine, p-CPA) did not influence H₂O₂-induced chilling tolerance. The positive regulation of MT on the antioxidant system, photosynthesis and cold response gene levels were significantly attenuated in RBOH1-RNAi plants compared with WT plants. These findings suggest that H₂O₂ may functions as a downstream signaling molecule in MT-induced chilling tolerance in cucumber plants.

Key message: Established an Agrobacterium-mediated hairy root transformation system for gene function analysis in Lathyrus sativus. Arabidopsis mutant complementation and genome editing in Lathyrus confirmed role of LsOCS in the oxalate metabolism. Grass pea (Lathyrus sativus) is a resilient legume cultivated for its protein-rich seeds and fodder. However, the presence of a naturally occurring neurotoxin, β-N-oxalyl-L-α,β-diaminopropionic acid (β-ODAP), which causes neurolathyrism, limits its extensive cultivation. This paper reports the in-planta characterization of oxalyl-CoA synthetase (OCS), an enzyme involved in oxalate metabolism and important in the oxalylating step leading to β-ODAP production in Lathyrus. For this, we used complementation experiments in an Arabidopsis OCS mutant. The LsOCS-complemented lines showed oxalate content similar to wild-type levels, and the analysis of seeds by field emission scanning electron microscope (FESEM) showed that the LsOCS-complemented lines were rescued from seed-coat defects found in the mutant seeds. We used genome editing of LsOCS in Lathyrus hairy roots to further characterize LsOCS function. The mutations in LsOCS resulted in the accumulation of oxalate in the hairy roots of Lathyrus, as observed in Arabidopsis mutants, but did not affect the ODAP levels. The hairy root genome editing system could serve as a rapid tool for functional studies of Lathyrus genes and optimizing the agronomic traits.

Waterlogging stands as a common environmental challenge, significantly affecting plant growth, yield, and, in severe cases, survival. In response to waterlogging stress, plants exhibit a series of intricate physiologic, metabolic, and morphologic adaptations. Notably, the gaseous phytohormone ethylene is rapidly accumulated in the plant submerged tissues, assuming an important regulatory factor in plant-waterlogging tolerance. In this review, we summarize recent advances in research on the mechanisms of ethylene in the regulation of plant responses to waterlogging stress. Recent advances found that both ethylene biosynthesis and signal transduction make indispensable contributions to modulating plant adaptation mechanisms to waterlogged condition. Ethylene was also discovered to play an important role in plant physiologic metabolic responses to waterlogging stress, including the energy mechanism, morphologic adaptation, ROS regulation and interactions with other phytohormones. The comprehensive exploration of ethylene and its associated genes provides valuable insights into the precise strategies to leverage ethylene metabolism for enhancing plant resistance to waterlogging stress.

Key message: The pathogenesis-related 1 gene of watermelon responds to the infection of ZYMV and contributes to the resistance of its host. Zucchini yellow mosaic virus (ZYMV; family Potyviridae) is a single-stranded positive-sense RNA virus that is a serious threat to cucurbits. Previously, we observed a hypersensitivity response (HR) in the systemic leaves of the 938-16-B watermelon line infected with ZYMV, distinct from the typical HR at infected sites. In this study, we confirmed that ZYMV accumulation in 938-16-B was significantly lower than in the susceptible line H1. Upon inoculation, the entry of ZYMV-eGFP into mesophyll cells is restricted into necrotic spots in leaves, indicating that resistance to ZYMV in 938-16-B is linked to the HR. Further, grafting experiments between 938-16-B and susceptible varieties were performed, and revealed an HR induction in susceptible varieties, suggesting the transfer of resistance signal(s) from 938-16-B to susceptible varieties. Through RNA-sequencing and proteomics analyses of the H1 scions on 938-16-B rootstock, a pathogenesis-related 1 (ClPR1) gene was identified. Specifically, ClPR1 expression is unique to ZYMV-infected 938-16-B. Repression of the expression of ClPR1 prevents an HR in 938-16-B. Conversely, overexpression of ClPR1 in susceptible varieties significantly reduces ZYMV accumulation, but an HR was not induced in susceptible line. Besides the virus, jasmonic acid (JA) can also trigger an HR in 938-16-B. Intriguingly, the expression of ClPR1 (Cla97C02G034020) is induced in both of 938-16-B and H1 by MeJA, rather than salicylic acid. These results suggest that HR is associated with the expression of ClPR1 and contributes to resistance to ZYMV in 938-16-B.

Key message: PlZAT10-PlCYP707A2 module promotes Paeonia lactiflora seeds germination. The herbaceous peony (Paeonia lactiflora) seeds exhibit double dormancy in the epicotyl and hypocotyl, which significantly inhibits the process of cultivation and breeding of new varieties. Nevertheless, the molecular mechanism underlying seed dormancy release in P. lactiflora remains to be fully identified. In this current study, we analyzed differentially expressed genes based on transcriptome data and selected the abscisic acid catabolic gene PlCYP707A2 for further investigation. The conserved domain of the protein indicated that PlCYP707A2 possessed a cytochrome P450 monooxygenase domain. Subcellular localization indicated that PlCYP707A2 was localized on the cytoplasm and cell membrane. Overexpression of PlCYP707A2 in P. lactiflora seeds decreased ABA contents and promoted seeds germination. The silencing of PlCYP707A2 resulted in seed dormancy and an alteration in the content of ABA. Moreover, yeast one-hybrid, electrophoretic mobility shift and dual-luciferase reporter assay revealed that PlZAT10 bound to the promoter of PlCYP707A2. In conclusion, the results demonstrated the mechanism of the PlZAT10-PlCYP707A2 module in regulating the dormancy release of P. lactiflora seeds, enriching relevant theories on seed dormancy and having significant implications for the herbaceous peony industry developing.

Key message: The SBP-box transcription factor PlSPL2 silencing in herbaceous peony enhanced stem strength by regulating xylem development, whereas its overexpression in tobacco resulted in weaker stem strength and undeveloped xylem. The strength of plant stems is a critical determinant of lodging resistance of plants, which significantly affects crop yield and cut-flower quality. Squamosa promoter binding (SBP) protein-like (SPL) transcription factors (TFs), participate in multiple regulatory processes, particularly in stem development. In this study, PlSPL2, an orthologous gene of Arabidopsis AtSPL2 in herbaceous peony, was isolated and found to contain a conserved SBP domain featuring two typical Zn-binding sites, as well as a nuclear localization sequence (NLS). Subsequently, transient infection of tobacco leaf epidermal cells using Agrobacterium confirmed the nuclear localization of PISPL2 protein. Additionally, gene expression analyses revealed that PlSPL2 was preferentially expressed in stems, and demonstrated a download trend in expression levels within vascular bundles during stem cell wall development. Furthermore, silencing of PlSPL2 in herbaceous peony enhanced stem strength. The silenced plants exhibited more developed xylems with wider radii and higher numbers of cell layers. Overexpression of PlSPL2 in tobacco, however, resulted in weaker stem strength, accompanied by a narrower radius of the xylem. These findings suggested that PlSPL2 was a negative regulator of herbaceous peony stem development, and its discovery and research could significantly contribute to a deeper understanding of stem growth and development mechanisms.

The ability to efficiently genetically modify plant species is crucial, driving the need for innovative technologies in plant biotechnology. Existing plant genetic transformation systems include Agrobacterium-mediated transformation, biolistics, protoplast-based methods, and nanoparticle techniques. Despite these diverse methods, many species exhibit resistance to transformation, limiting the applicability of most published methods to specific species or genotypes. Tissue culture remains a significant barrier for most species, although other barriers exist. These include the infection and regeneration stages in Agrobacterium, cell death and genomic instability in biolistics, the creation and regeneration of protoplasts for protoplast-based methods, and the difficulty of achieving stable transformation with nanoparticles. To develop species-independent transformation methods, it is essential to address these transformation bottlenecks. This review examines recent advancements in plant biotechnology, highlighting both new and existing techniques that have improved the success rates of plant transformations. Additionally, several newly emerged plant model systems that have benefited from these technological advancements are also discussed.

Key message: Based on transport inhibition and genome-wide analysis, 123 ABC transporters of Euphorbia lathyris were identified, and it was found that the PDR family members ElABCG39 mediated ingenol efflux. Identification of ingenol biosynthetic enzymes and transporters in plant is fundamental to realize its biosynthesis in chassis cells. At present, several key enzymes of the ingenol biosynthesis pathway have been identified, while the mechanisms governing the accumulation or transport of ingenol to distinct plant tissue compartments remain elusive. In this study, transport inhibition analyses were performed, along with genome-wide identification of 123 genes encoding ABC proteins in Euphorbia lathyris L., eventually discovering that a PDR transporter ElABCG39 mediates ingenol transmembrane transport and is localized on the plasma membrane. Expression of this protein in yeast AD1-8 promoted the transmembrane efflux of ingenol with strong substrate specificity. Furthermore, in ElABCG39 RNAi transgenic hairy roots, ingenol transmembrane efflux was significantly reduced and hairy root growth was inhibited. The discovery of the first Euphorbia macrocyclic diterpene transporter ElABCG39 has not only further improved the ingenane diterpenoid biosynthesis regulatory network, but also provided a new key element for ingenol production in chassis cells.