Plant and Cell Physiology最新文献

CANTATAdb 3.0 is an updated database of plant long non-coding RNAs (lncRNAs), containing 571,688 lncRNAs identified across 108 species, including 100 Magnoliopsida (flowering plants), a significant expansion from the previous version. A notable feature is the inclusion of 112,980 lncRNAs that are expressed specifically in certain plant organs or embryos, indicating their potential role in development and organ-specific processes. In addition, CANTATAdb 3.0 includes 74,886 pairs of evolutionarily conserved lncRNAs found across 47 species and inferred from genome-genome alignments as well as conserved lncRNAs obtained using a similarity search approach in 5,479 species pairs, which would further aid in the selection of lncRNAs for functional studies. Interestingly, we find that conserved lncRNAs with tissue-specific expression patterns tend to occupy the same plant organ across different species, pointing toward conserved biological roles. The database now offers extended search capabilities and downloadable data in popular formats, further facilitating research on plant lncRNAs.

The INDUCER OF CBF EXPRESSION 1/C-REPEAT BINDING FACTOR (ICE1/CBF) pathway plays a crucial role in plant responses to cold stress, impacting growth and development. Here, we demonstrated that ATBS1-INTERACTING FACTOR 2 (AIF2), a non-DNA-binding basic helix-loop-helix transcription factor, positively regulates freezing tolerance through the ICE1/CBF-induced cold tolerance pathway in Arabidopsis. Cold stress transcriptionally upregulated AIF2 expression and induced AIF2 phosphorylation, thereby stabilizing the AIF2 protein during early stages of cold acclimation. The AIF2 loss-of-function mutant, aif2-1, exhibited heightened sensitivity to freezing before and after cold acclimation. In contrast, ectopic expression of AIF2, but not the C-terminal-deleted AIF2 variant, restored freezing tolerance. AIF2 enhanced ICE1 stability during cold acclimation and promoted the transcriptional expression of CBFs and downstream cold-responsive genes, ultimately enhancing plant tolerance to freezing stress. MITOGEN-ACTIVATED PROTEIN KINASES 3 and 6 (MPK3/6), known negative regulators of freezing tolerance, interacted with and phosphorylated AIF2, subjecting it to protein degradation. Furthermore, transient co-expression of MPK3/6 with AIF2 and ICE1 downregulated AIF2/ICE1-induced transactivation of CBF2 expression. AIF2 interacted preferentially with BRASSINOSTEROID-INSENSITIVE 2 (BIN2) and MPK3/6 during the early and later stages of cold acclimation, respectively, thereby differentially regulating AIF2 activity in a cold acclimation time-dependent manner. Moreover, AIF2 acted additively in a gain-of-function mutant of BRASSINAZOLE-RESISTANT 1 (BZR1; bzr1-1D) and a triple knockout mutant of BIN2 and its homologs (bin2bil1bil2) to induce CBFs-mediated freezing tolerance. This suggests that cold-induced AIF2 coordinates freezing tolerance along with BZR1 and BIN2, key positive and negative components, respectively, of brassinosteroid signaling pathways.

High-affinity potassium transporters (HKTs) play an important role in plants responding to salt stress, but the transport properties of the soybean HKT transporters at the molecular level are still unclear. Here, using Xenopus oocyte as a heterologous expression system and two-electrode voltage-clamp technique, we identified four HKT transporters, GmHKT1;1, GmHKT1;2, GmHKT1;3 and GmHKT1;4, all of which belong to type I subfamily, but have distinct ion transport properties. While GmHKT1;1, GmHKT1;2 and GmHKT1;3 function as Na+ transporters, GmHKT1;1 is less selective against K+ than the two other transporters. Astonishingly, GmHKT1;4, which lacks transmembrane segments and has no ion permeability, is significantly expressed, and its gene expression pattern is different from the other three GmHKTs under salt stress. Interestingly, GmHKT1;4 reduced the Na+/K+ currents mediated by GmHKT1;1. Further study showed that the transport ability of GmHKT1;1 regulated by GmHKT1;4 was related to the structural differences in the first intracellular domain and the fourth repeat domain. Overall, we have identified one unique GmHKT member, GmHKT1;4, which modulates the Na+ and K+ transport ability of GmHKT1;1 via direct interaction. Thus, we have revealed a new type of HKT interaction model for altering their ion transport properties.

As a model plant for bryophytes, Marchantia polymorpha offers insights into the role of RNA silencing in aiding early land plants navigate the challenges posed by high-temperature environments. Genomic analysis revealed unique ARGONAUTE1 ortholog gene (MpAGO1) in M. polymorpha, which is regulated by two species-specific microRNAs (miRNAs), miR11707.1 and miR11707.2. Comparative studies of small RNA profiles from M. polymorpha cellular and MpAGO1 immunoprecipitation (MpAGO1-IP) profiles at various temperatures, along with analyses of Arabidopsis AGO1 (AtAGO1), revealed that MpAGO1 has a low selectivity for a diverse range of small RNA species than AtAGO1. Protein structural comparisons revealed no discernible differences in the guide strand small RNA recognition middle domain, MID domain, of MpAGO1 and AtAGO1, suggesting the complexity of miRNA species specificity and necessitating further exploration. Small RNA profiling and size exclusion chromatography have pinpointed a subset of M. polymorpha miRNAs, notably miR11707, that remain in free form within the cell at 22°C but are loaded into MpAGO1 at 28°C to engage in RNA silencing. Investigations into the mir11707 gene editing (mir11707ge) mutants provided evidence of the regulation of miR11707 in MpAGO1. Notably, while MpAGO1 mRNA expression decreases at 28°C, the stability of the MpAGO1 protein and its associated miRNAs is essential for enhancing the RNA-inducing silencing complex (RISC) activity, revealing the importance of RNA silencing in enabling M. polymorpha to survive thermal stress. This study advances our understanding of RNA silencing in bryophytes and provides groundbreaking insights into the evolutionary resilience of land plants to climatic adversities.

Understanding how plants respond to temperature is relevant for agriculture in a warming world. Responses to temperature in the shoot have been characterized more fully than those in the root. Previous work on thermomorphogenesis in roots established that for Arabidopsis thaliana (Columbia) seedlings grown continuously at a given temperature, the root meristem produces cells at the same rate at 15°C as at 25°C and the root's growth zone is the same length. To uncover the pathway(s) underlying this constancy, we screened 34 A. thaliana genotypes for parameters related to growth and division. No line failed to respond to temperature. Behavior was little affected by mutations in phytochrome or other genes that underly thermomorphogenesis in shoots. However, a mutant in cryptochrome 2 was disrupted substantially in both cell division and elongation, specifically at 15°C. Among the 34 lines, cell production rate varied extensively and was associated only weakly with root growth rate; in contrast, parameters relating to elongation were stable. Our data are consistent with models of root growth that invoke cell non-autonomous regulation for establishing boundaries between meristem, elongation zone and mature zone.

Group II introns are large catalytic RNAs, which reside mainly within genes encoding respiratory complex I (CI) subunits in angiosperms' mitochondria. Genetic and biochemical analyses led to the identification of many nuclear-encoded factors that facilitate the splicing of the degenerated organellar introns in plants. Here, we describe the analysis of the pentatricopeptide repeat (PPR) co-expressed intron splicing-1 (PCIS1) factor, which was identified in silico by its co-expression pattern with many PPR proteins. PCIS1 is well conserved in land plants but has no sequence similarity with any known protein motifs. PCIS1 mutant lines are arrested in embryogenesis and can be maintained by the temporal expression of the gene under the embryo-specific ABI3 promoter. The pABI3::PCIS1 mutant plants display low germination and stunted growth phenotypes. RNA-sequencing and quantitative RT-PCR analyses of wild-type and mutant plants indicated that PCIS1 is a novel splicing cofactor that is pivotal for the maturation of several nad transcripts in Arabidopsis mitochondria. These phenotypes are tightly associated with respiratory CI defects and altered plant growth. Our data further emphasize the key roles of nuclear-encoded cofactors that regulate the maturation and expression of mitochondrial transcripts for the biogenesis of the oxidative phosphorylation system, and hence for plant physiology. The discovery of novel splicing factors other than typical RNA-binding proteins suggests further complexity of splicing mechanisms in plant mitochondria.

Sorghum [Sorghum bicolor (L.) Moench] has been receiving attention as a feedstock for lignocellulose biomass energy. During the combustion process, the ash containing silicon (Si) can be produced, which causes problems in furnace maintenance. Hence, lowering Si content in the plants is crucial. Nevertheless, limiting Si supply to crops is difficult in practice because Si is abundant in soil. Previously, a Si uptake transporter (SbLsi1) has been identified, and the Si-depleted mutant has also been generated in the model sorghum variety BTx623. In this study, we aim to investigate the change induced by the mutation of SbLsi1 on the accumulation and the structure of lignin in cell walls. Through chemical and NMR analyses, we demonstrated that the lsi1 mutation resulted in a significant increase in lignin accumulation levels as well as a significant reduction in Si content. At least some of the modification was induced by transcriptional changes, as suggested by the upregulation of phenylpropanoid biosynthesis-related genes in the mutant plants. These findings derived from the model variety would be useful for the future development of practical cultivars with high biomass and less Si content for bioenergy applications.

Iron availability within the root system of plants fluctuates depending on various soil factors, which directly impacts plant growth. Simultaneously, various environmental stressors, such as high/low temperatures and high light intensity, affect plant photosynthesis in the leaves. However, the combined effects of iron nutrient conditions and abiotic stresses have not yet been clarified. In this study, we analyzed how iron nutrition conditions impact the chilling-induced damage on cucumber leaves (Cucumis sativus L.). When cucumbers were grown under different iron conditions and then exposed to chilling stress, plants grown under a high-iron condition exhibited more severe chilling-induced damage than the control plants. Conversely, plants grown under a low iron condition showed an alleviation of the chilling-induced damages. These differences were observed in a light-dependent manner, indicating that iron intensified the toxicity of reactive oxygen species generated by photosynthetic electron transport. In fact, plants grown under the low iron condition showed less accumulation of malondialdehyde derived from lipid peroxidation after chilling stress. Notably, the plants grown under the high-iron condition displayed a significant accumulation of iron and an increase in lipid peroxidation in the shoot, specifically after light-chilling stress, but not after dark-chilling stress. This indicated that increased root-to-shoot iron translocation, driven by light and low temperature, exacerbated leaf oxidative damage during chilling stress. These findings also highlight the importance of managing iron nutrition in the face of chilling stress and will facilitate crop breeding and cultivation strategies.

Speciation is the process leading to the emergence of new species. While being usually progressive, it can sometimes be fast with rapid emergence of reproductive barriers leading to high level of reproductive isolation. Some reproductive barriers might leave signatures in the genome, through elevated level of genetic differentiation at specific loci. Similar signatures might also be the results of linked selection acting in low recombination regions. Nottingham catchfly (Silene nutans) is a Caryophyllaceae species composed of four genetically differentiated lineages for which strong and asymmetric levels of reproductive isolation have been identified. Using population transcriptomic data from several individuals of the four lineages, we inferred the best evo-demographic scenario leading to the current reproductive isolation of these four lineages. We also tested whether loci exhibiting high level of genetic differentiation represented barrier loci or were located in low recombination regions, evolving under strong influence of linked selection. Overall, the four lineages of S. nutans have diverged in strict isolation, likely during the different glacial period, through migration in distinct glacial refugia. Speciation between these four lineages appeared to be particularly fast, likely due to fast evolving plastid genome accelerating plastid-nuclear co-evolution and the probability of plastid-nuclear incompatibilities in inter-lineage hybrids.

In Arabidopsis, RNA editing alters more than 500 cytidines (C) to uridines (U) in mitochondrial transcripts, a process involving the family of pentatricopeptide repeat (PPR) proteins. Here, we report a previously uncharacterized mitochondrial PLS-type PPR protein, GEND2, which functions in the mitochondrial RNA editing. The T-DNA insertion in the 5'-untranslated region of GEND2, referred to as gend2-1, results in defective root development compared to wild-type (WT) plants. A comprehensive examination of mitochondrial RNA editing sites revealed a significant reduction in the gend2-1 mutant compared to WT plants, affecting six specific mitochondrial RNA editing sites, notably within the mitochondrial genes CcmFn-1, RPSL2 and ORFX. These genes encode critical components of cytochrome protein maturation pathway, mitochondrial ribosomal subunit, and twin arginine translocation subunits, respectively. Further analysis of the transcriptional profile of the gend2-1 mutant and wild type revealed a striking induction of expression in a cluster of genes associated with mitochondrial dysfunction and regulated by ANAC017, a key regulator coordinating organelle functions and stress responses. Intriguingly, the gend2-1 mutation activated an ANAC017-dependent signaling aimed at countering cell wall damage induced by cellulose synthase inhibitors, as well as an ANAC017-independent pathway that retarded root growth under normal condition. Collectively, our findings identify a novel mitochondrial PLS-type PPR protein GEND2, which participates in the editing of six specific mitochondrial RNA editing sites. Furthermore, the gend2-1 mutation triggers two distinct pathways in plants: an ANAC017-dependent pathway and ANAC017-independent pathway.