Family Of Plant Proteins Research Articles

Sequence characteristics, expression and subcellular localization of PtCYP721A57 gene from cytochrome P450 family in Polygala tenuifolia willd.

The Cytochrome P450 (CYP450) family is the largest enzyme protein family in plants, distributed across various organs and involved in significant catalytic activities in primary and secondary metabolic processes. In this study, we cloned the PtCYP721A57 gene, characterized its open reading frame (ORF), and conducted comprehensive analyses including physicochemical properties, evolutionary relationships, subcellular localization, prokaryotic expression, and correlation between the relative expression of different parts and the content of tenuifolin, hormones, and abiotic stress response associated with the encoded protein. The ORF of PtCYP721A57 was 1,521 bp, with a secondary structure predominantly composed of α-helices and random coils. Subcellular localization experiments confirmed the presence of PtCYP721A57 in the endoplasmic reticulum. For prokaryotic expression, we constructed the recombinant plasmid pET28a-PtCYP721A57 using pET28a as the vector, which was then transformed into BL21(DE3). Induction with Isopropyl β-D-1-thiogalactopyranoside (IPTG) at temperatures of 16 and 25 °C and varying concentrations (0.1, 0.2, 0.5, 1, 2 mM) resulted in the formation of inclusion bodies, with higher expression observed at 25 °C. Our qPCR analyses revealed that PtCYP721A57 exhibited the highest expression in the cortex of Polygala tenuifolia, followed by roots and xylem, correlating with the observed tenuifolin content distribution. Induction with abscisic acid (ABA) and chitosan (CHT) initially decreased PtCYP721A57 expression followed by a subsequent increase, peaking at 48 h. Similarly, drought stress induced a gradual increase in PtCYP721A57 expression, also peaking at 48 h. NaCl treatment for 6 h significantly upregulated PtCYP721A57 expression. In conclusion, our study provides foundational insights into the PtCYP721A57 gene in Polygala tenuifolia, laying the groundwork for further exploration of its role in the biosynthesis pathway of triterpenoid saponins.

Molecular evolution and functional diversification of metal tolerance protein families in cereals plants and function of maize MTP protein

Plants employ metal tolerance proteins (MTPs) to confer tolerance by sequestering excess ions into vacuoles. MTPs belong to the cation diffusion facilitator (CDF) family, which facilitates the transport of divalent transition metal cations. In this study, we conducted a comprehensive analysis of the MTP gene families across 21 plant species, including maize (Zea mays). A total of 247 MTP genes were identified within these plant genomes and categorized into distinct subgroups, namely Zn-CDF, Mn-CDF, and Fe/Zn-CDF, based on phylogenetic analyses. This investigation encompassed the characterization of genomic distribution, gene structures, cis-regulatory elements, collinearity relationships, and gene ontology functions associated with MTPs. Transcriptomic analyses unveiled stress-specific expression patterns of MTP genes under various abiotic stresses. Moreover, quantitative RT-PCR assays were employed to assess maize MTP gene responses to diverse heavy metal stress conditions. Functional validation of metal tolerance roles was achieved through heterologous expression in yeast. This integrated evolutionary scrutiny of MTP families in cereals furnishes a valuable framework for the elucidation of MTP functions in subsequent studies. Notably, the prioritized MTP gene ZmMTP6 emerged as a positive regulator of plant Cd tolerance, thereby offering a pivotal genetic asset for the development of Cd-tolerant crops, particularly maize cultivars.

The pentatricopeptide repeat protein TCD6 functions RNA editing and cleavage of ndhA and is required for chloroplast development in early rice seedlings

Pentatricopeptide repeat (PPR) proteins compose one of the largest protein families in higher plants and play a role in regulating organellar gene expression. In this study, we discovered that a new rice mutant tcd6 exhibited albino phenotype and aberrant chloroplast before the three-leaf (autotrophic) seedling stage. Through Map-based cloning and complementation tests, it was shown that TCD6 encodes a chloroplast-located PPR protein, with 14 PPR motifs and an atypical DYW-like motif. In addition, the disruption of TCD6 hindered the nuclear-encoded polymerase (NEP)-dependent transcript levels for plastid genes and led to defects in the cleavage and editing of ndhA (encoding NDH subunit) in early tcd6 mutant seedlings. Taken together, our results indicate that TCD6 is indispensable for chloroplast development and involves in RNA editing and cleavage of ndhA during early seedling (autotrophic) growth of rice.

PPR proteins in plants: roles, mechanisms, and prospects for rice research.

Pentatricopeptide repeat (PPR) proteins constitute one of the largest protein families in land plants, with over 300 members in various species. Nearly all PPR proteins are nuclear-encoded and targeted to the chloroplast and mitochondria, modulating organellar gene expression by participating in RNA metabolism, including mRNA stability, RNA editing, RNA splicing, and translation initiation. Organelle RNA metabolism significantly influences chloroplast and mitochondria functions, impacting plant photosynthesis, respiration, and environmental responses. Over the past decades, PPR proteins have emerged as a research focus in molecular biology due to their diverse roles throughout plant life. This review summarizes recent progress in understanding the roles and molecular mechanisms of PPR proteins, emphasizing their functions in fertility, abiotic and biotic stress, grain quality, and chloroplast development in rice. Furthermore, we discuss prospects for PPR family research in rice, aiming to provide a theoretical foundation for future investigations and applications.

Analysis of RNA Recognition and Binding Characteristics of OsCPPR1 Protein in Rice

Pentatricopeptide repeat (PPR) proteins represent one of the largest protein families in plants and typically localize to organelles like mitochondria and chloroplasts. By contrast, CYTOPLASM- LOCALIZED PPR1 (OsCPPR1) is a cytoplasm-localized PPR protein that can degrade OsGOLDEN- LIKE1 (OsGLK1) mRNA in the tapetum of rice anther. However, the mechanism, by which OsCPPR1 recognizes and binds to OsGLK1 transcripts, remains unknown. Through protein structure prediction and macromolecular docking experiments, we observed that distinct PPR motif structures of OsCPPR1 exhibited varying binding efficiencies to OsGLK1 RNA. Moreover, RNA-electrophoretic mobility shift assay experiment demonstrated that the recombinant OsCPPR1 can directly recognize and bind to OsGLK1 mRNA in vitro. This further confirmed that the mutations in the conserved amino acids in each PPR motif resulted in loss of activity, while truncation of OsCPPR1 decreased its binding efficiency. These findings collectively suggest that it may require some co-factors to assist in cleavage, a facet that warrants further exploration in subsequent studies.

Down-Regulation of Rice Glutelin by CRISPR-Cas9 Gene Editing Decreases Carbohydrate Content and Grain Weight and Modulates Synthesis of Seed Storage Proteins during Seed Maturation

The glutelins are a family of abundant plant proteins comprised of four glutelin subfamilies (GluA, GluB, GluC, and GluD) encoded by 15 genes. In this study, expression of subsets of rice glutelins were suppressed using CRISPR-Cas9 gene-editing technology to generate three transgenic rice variant lines, GluA1, GluB2, and GluC1. Suppression of the targeted glutelin genes was confirmed by SDS-PAGE, Western blot, and q-RT-PCR. Transgenic rice variants GluA1, GluB2, and GluC1 showed reduced amylose and starch content, increased prolamine content, reduced grain weight, and irregularly shaped protein aggregates/protein bodies in mature seeds. Targeted transcriptional profiling of immature seeds was performed with a focus on genes associated with grain quality, starch content, and grain weight, and the results were analyzed using the Pearson correlation test (requiring correlation coefficient absolute value ≥ 0.7 for significance). Significantly up- or down-regulated genes were associated with gene ontology (GO) and KEGG pathway functional annotations related to RNA processing (spliceosomal RNAs, group II catalytic introns, small nucleolar RNAs, microRNAs), as well as protein translation (transfer RNA, ribosomal RNA and other ribosome and translation factors). These results suggest that rice glutelin genes may interact during seed development with genes that regulate synthesis of starch and seed storage proteins and modulate their expression via post-transcriptional and translational mechanisms.

Arabidopsis CML13 andCML14 Have Essential andOverlapping Roles inPlant Development.

Calmodulin (CaM)-like proteins (CMLs) are the largest family of calcium-binding proteins in plants, yet the functions of most CMLs are unknown. Arabidopsis CML13 and CML14 are closely related paralogs that interact with the isoleucine-glutamine (IQ) domains of myosins, IQ-domain proteins and CaM-binding transcription activators (CAMTAs). Here, we explored the physiological roles of CML13 and CML14 during development by using dexamethasone (Dex)-inducible RNA silencing to suppress either CML13 or CML14 transcript levels. In the absence of inducible suppression, CML13- and CML14-RNA-interference lines were indistinguishable from wild-type (WT) plants throughout development. In contrast, induction of silencing treatment led to rapid increases in RNA-hairpin production that correlated with a targeted reduction in CML13 or CML14 transcript levels and a range of developmental and morphological effects. RNA-suppression treatment did not impair the germination of CML13- or 14-RNA-interference lines, but these seedlings were chlorotic, displayed high mortality and failed to achieve seedling establishment. Under Dex treatment, seeds of CML13- and CML14-RNA-interference lines exhibited differential sensitivity to exogenous ABA compared to WT seeds. Induced RNA suppression of mature plants led to reduced silique length, shorter roots and rapid leaf senescence in CML13- and 14-RNA-interference plants, which correlated with increased gene expression of the senescence marker Senescence-Associated Gene13 (SAG13). Plants induced for RNA suppression at 2 weeks post-germination exhibited a much stronger phenotype than treatment of 3-, 4- or 5-week-old plants. Collectively, our data indicate that both CML13 and CML14 are essential for normal development and function across a broad range of tissues and developmental stages.

The cytochrome P450 gene, MdCYP716B1, is involved in regulating plant growth and anthracnose resistance in apple

Apple is one of the main cultivated fruit trees worldwide. Both biotic and abiotic stresses, especially fungal diseases, have serious effects on the growth and fruit quality of apples. Cytochrome P450, the largest protein family in plants, is critical for plant growth and stress responses. However, the function of apple P450 remains poorly understood. In our previous study, ‘Hanfu’ autotetraploid showed dwarfism and fungal resistance phenotypes compared to ‘Hanfu’ diploid. Digital gene expression sequencing analysis revealed that the transcript level of MdCYP716B1 was significantly downregulated in the autotetraploid apple cultivar ‘Hanfu’. In this study, we identified and cloned the MdCYP716B1 gene from ‘Hanfu’ apples. The MdCYP716B1 protein fused to a green fluorescent protein was localized in the cytoplasm. We constructed the plant overexpression vector and RNAi vector of MdCYP716B1, and the apple ‘GL-3’ was transformed by Agrobacterium-mediated transformation to obtain transgenic plants. Overexpressing and RNAi silencing transgenic plants exhibited an increase and decrease in plant height to ‘GL-3’, respectively. RNAi silencing transgenic plants displayed increased resistance to Colletotrichum gloeosporioides, whereas overexpression transgenic plants were more sensitive to C. gloeosporioides. According to transcriptome analysis, the transcript levels of gibberellin biosynthesis genes were upregulated in MdCYP716B1-overexpression plants. In contrast with ‘GL-3’, GA3 accumulation was rose in MdCYP716B1-OE lines and impaired in MdCYP716B1-RNAi lines. Collectively, our data indicate that MdCYP716B1 regulates plant growth and resistance to fungal stress.

Comprehensive analyses of microtubule-associated protein MAP65 family genes in Cucurbitaceae and CsaMAP65s expression profiles in cucumber.

MAP65 is a microtubule-binding protein family in plants and plays crucial roles in regulating cell growth and development, intercellular communication, and plant responses to various environmental stresses. However, MAP65s in Cucurbitaceae are still less understood. In this study, a total of 40 MAP65s were identified from six Cucurbitaceae species (Cucumis sativusL., Citrullus lanatus, Cucumis melo L., Cucurbita moschata, Lagenaria siceraria, and Benincasa hispida) and classified into five groups by phylogenetic analysis according to gene structures and conserved domains. A conserved domain (MAP65_ASE1) was found in all MAP65 proteins. In cucumber, we isolated six CsaMAP65s with different expression patterns in tissues including root, stem, leaf, female flower, male flower, and fruit. Subcellular localizations of CsaMAP65s verified that all CsaMAP65s were localized in microtubule and microfilament. Analyses of the promoter regions of CsaMAP65s have screened different cis-acting regulatory elements involved in growth and development and responses to hormone and stresses. In addition, CsaMAP65-5 in leaves was significantly upregulated by salt stress, and this promotion effect was higher in cucumber cultivars with salt tolerant than that without salt tolerant. CsaMAP65-1 in leaves was significantly upregulated by cold stress, and this promotion was higher in cold-tolerant cultivar than intolerant cultivar. With the genome-wide characterization and phylogenetic analysis of Cucurbitaceae MAP65s, and the expression profile of CsaMAP65s in cucumber, this study laid a foundation for further study on MAP65 functions in developmental processes and responses to abiotic stress in Cucurbitaceae species.

Role of the plant-specific calcium-binding C2-DOMAIN ABSCISIC ACID-RELATED (CAR) protein family in environmental signaling

Many signaling processes rely on information decoding at the plasma membrane, and membrane-associated proteins and their complexes are fundamental for regulating this process. Still many questions exist as to how protein complexes are assembled and function at membrane sites to change identity and dynamics of membrane systems. Peripheral membrane proteins containing a calcium and phospholipid-binding C2-domain can act in membrane-related signaling by providing a tethering function so that protein complexes form. C2 domain proteins termed C2-DOMAIN ABSCISIC ACID-RELATED (CAR) proteins are plant-specific, and the functional relevance of this C2 domain protein subgroup is just emerging. The ten Arabidopsis CAR proteins CAR1 to CAR10 have a single C2 domain with a plant-specific insertion, the so-called “CAR-extra-signature” or also termed “sig domain”. Via this “sig domain” CAR proteins can bind signaling protein complexes of different kinds and act in biotic and abiotic stress, blue light and iron nutrition. Interestingly, CAR proteins can oligomerize in membrane microdomains, and their presence in the nucleus can be linked with nuclear protein regulation. This shows that CAR proteins may play unprecedented roles in coordinating environmental responses and assembling required protein complexes to transmit information cues between plasma membrane and nucleus. The aim of this review is to summarize structure-function characteristics of the CAR protein family and assemble findings from CAR protein interactions and physiological functions. From this comparative investigation we extract common principles about the molecular operations that CAR proteins may fulfill in the cell. We also deduce functional properties of the CAR protein family based on its evolution and gene expression profiles. We highlight open questions and suggest novel avenues to prove and understand the functional networks and roles played by this protein family in plants.

Genome-Wide Identification and Bioinformatics Analyses of Host Defense Peptides Snakin/GASA in Mangrove Plants.

Host defense peptides (HDPs) are components of plant defensive barriers that resist microbial infection. Members of the Snakin/GASA protein family in plants have functions of regulating plant growth, defense, and bacteriostasis. Most mangrove plants grow in coastal zones. In order to survive in harsh environments, mangrove plants have evolved complex adaptations against microbes. In this study, Snakin/GASA family members were identified and analyzed in the genomes of three mangrove species. Twenty-seven, thirteen, and nine candidate Snakin/GASA family members were found in Avicennia marina, Kandelia obovata, and Aegiceras corniculatum, respectively. These Snakin/GASA family members were identified and categorized into three subfamilies via phylogenetic analysis. The genes coding for the Snakin/GASA family members were unevenly distributed on chromosomes. Collinearity and conservative motif analyses showed that the Snakin/GASA family members in K. obovata and A. corniculatum underwent multiple gene duplication events. Snakin/GASA family member expression in normal leaves and leaves infected with pathogenic microorganisms of the three mangrove species was verified using real-time quantitative polymerase chain reaction. The expression of KoGASA3 and 4, AcGASA5 and 10, and AmGASA1, 4, 5, 15, 18, and 23 increased after microbial infection. This study provides a research basis for the verification of HDPs from mangrove plants and suggests directions for the development and utilization of marine biological antimicrobial peptides.

Genome-wide identification of bHLH transcription factors and their response to salt stress in Cyclocarya paliurus.

As a highly valued and multiple function tree species, the leaves of Cyclocarya paliurus are enriched in diverse bioactive substances with healthy function. To meet the requirement for its leaf production and medical use, the land with salt stress would be a potential resource for developing C. paliurus plantations due to the limitation of land resources in China. The basic helix-loop-helix (bHLH) transcription factor protein family, the second largest protein family in plants, has been found to play essential roles in the response to multiple abiotic stresses, especially salt stress. However, the bHLH gene family in C.paliurus has not been investigated. In this study, 159 CpbHLH genes were successfully identified from the whole-genome sequence data, and were classified into 26 subfamilies. Meanwhile, the 159 members were also analyzed from the aspects of protein sequences alignment, evolution, motif prediction, promoter cis-acting elements analysis and DNA binding ability. Based on transcriptome profiling under a hydroponic experiment with four salt concentrations (0%, 0.15%, 0.3%, and 0.45% NaCl), 9 significantly up- or down-regulated genes were screened, while 3 genes associated with salt response were selected in term of the GO annotation results. Totally 12 candidate genes were selected in response to salt stress. Moreover, based on expression analysis of the 12 candidate genes sampled from a pot experiment with three salt concentrations (0%, 0.2% and 0.4% NaCl), CpbHLH36/68/146 were further verified to be involved in the regulation of salt tolerance genes, which is also confirmed by protein interaction network analysis. This study was the first analysis of the transcription factor family at the genome-wide level of C. paliurus, and our findings would not only provide insight into the function of the CpbHLH gene family members involved in salt stress but also drive progress in genetic improvement for the salt tolerance of C. paliurus.

Parallel evolution of two AIM24 protein subfamilies and their conserved functions in ER stress tolerance in land plants

Despite decades of efforts in genome sequencing and functional characterization, some important protein families remain poorly understood. In this study, we report the classification, evolution, and functions of the largely uncharacterized AIM24 protein family in plants, including the identification of a novel subfamily. We show that two AIM24 subfamilies (AIM24-A and AIM24-B) are commonly distributed in major plant groups. These two subfamilies not only have modest sequence similarities and different gene structures but also are of independent bacterial ancestry. We performed comparative functional investigations on the two AIM24 subfamilies using three model plants: the moss Physcomitrium patens, the liverwort Marchantia polymorpha, and the flowering plant Arabidopsis thaliana. Intriguingly, despite their significant differences in sequence and gene structure, both AIM24 subfamilies are involved in ER stress tolerance and the unfolded protein response (UPR). In addition, transformation of the AIM24-A gene from P. patens into the AIM24-B null mutant of A. thaliana could at least partially rescue ER stress tolerance and the UPR. We also discuss the role of AIM24 genes in plant development and other cellular activities. This study provides a unique example of parallel evolution in molecular functions and can serve as a foundation for further investigation of the AIM24 family in plants.

Insights into established and emerging roles of SR protein family in plants and animals.

Splicing of pre-mRNA is an essential part of eukaryotic gene expression. Serine-/arginine-rich (SR) proteins are highly conserved RNA-binding proteins present in all metazoans and plants. SR proteins are involved in constitutive and alternative splicing, thereby regulating the transcriptome and proteome diversity in the organism. In addition to their role in splicing, SR proteins are also involved in mRNA export, nonsense-mediated mRNA decay, mRNA stability, and translation. Due to their pivotal roles in mRNA metabolism, SR proteins play essential roles in normal growth and development. Hence, any misregulation of this set of proteins causes developmental defects in both plants and animals. SR proteins from the animal kingdom are extensively studied for their canonical and noncanonical functions. Compared with the animal kingdom, plant genomes harbor more SR protein-encoding genes and greater diversity of SR proteins, which are probably evolved for plant-specific functions. Evidence from both plants and animals confirms the essential role of SR proteins as regulators of gene expression influencing cellular processes, developmental stages, and disease conditions. This article is categorized under: RNA Processing > Splicing Mechanisms RNA Processing > Splicing Regulation/Alternative Splicing.

Gibberellin-regulated proteins: Emergent allergens.

About 10 years ago, a protein family was shown for the first time to contain allergenic members, gibberellin-regulated protein (GRP). The first reported member was from peach, Pru p 7. One can hypothesize that it was not detected before because its physicochemical characteristics overlap with those of lipid transfer protein (LTP), a well-known allergen, or because the exposure to GRP increased due to an increase in the gibberellin phythormone level in plant food, either exogenous or endogenous. Like LTPs, GRPs are small cationic proteins with disulfide bridges, are resistant to heat and proteolytic cleavage, and are involved in the defense of the plant. Besides peach, GRP allergens have been described in Japanese apricot (Pru m 7), sweet cherry (Pru av 7), orange (Cit s 7), pomegranate (Pun g 7), bell pepper (Cap a 7), strawberry (Fra a GRP), and also in pollen with a restriction to Cupressaceae tree family (Cup s 7, Cry j 7, and Jun a 7). IgE cross-reactivities were described between GRPs, and the reported peach/cypress and citrus/cypress syndromes may therefore be explained because of these GRP cross-reactivities. GRPs are clinically relevant, and severe adverse reactions may sometimes occur in association with cofactors. More than 60% and up to 95% sequence identities are calculated between various allergenic GRPs, and three-dimensional models show a cleft in the molecule and predict at least three epitopic regions. The structure of the protein and its properties and the matrix effect in the original allergenic source should be unraveled to understand why, despite the ubiquity of the protein family in plants, only a few members are able to sensitize patients.

Functional Characterization of Tomato ShROP7 in Regulating Resistance against Oidium neolycopersici.

ROPs (Rho-like GTPases from plants) are a unique family of small GTP-binding proteins in plants and play vital roles in numerous cellular processes, including growth and development, abiotic stress signaling, and plant defense. In the case of the latter, the role of ROPs as response regulators to obligate parasitism remains largely enigmatic. Herein, we isolated and identified ShROP7 and show that it plays a critical role in plant immune response to pathogen infection. Real-time quantitative PCR analysis revealed that the expression of ShROP7 was significantly increased during incompatible interactions. To establish its requirement for resistance, we demonstrate that virus-induced gene silencing (VIGS) of ShROP7 resulted in increased susceptibility of tomato to Oidium neolycopersici (On) Lanzhou strain (On-Lz). Downstream resistance signaling through H2O2 and the induction of the hypersensitive response (HR) in ShROP7-silenced plants were significantly reduced after inoculating with On-Lz. Taken together, with the identification of ShROP7-interacting candidates, including ShSOBIR1, we demonstrate that ShROP7 plays a positive regulatory role in tomato powdery mildew resistance.

MLO Proteins from Tomato (Solanum lycopersicum L.) and Related Species in the Broad Phylogenetic Context.

MLO proteins are a family of transmembrane proteins in land plants that play an important role in plant immunity and host–pathogen interactions, as well as a wide range of development processes. Understanding the evolutionary history of MLO proteins is important for understanding plant physiology and health. In the present work, we conducted a phylogenetic analysis on a large set of MLO protein sequences from publicly available databases, specifically emphasising MLOs from the tomato plant and related species. As a result, 4886 protein sequences were identified and used to construct a phylogenetic tree. In comparison to previous findings, we identified nine phylogenetic clades, revealed the internal structure of clades I and II as additional clades and showed the presence of monocotyledon species in all MLO clades. We identified a set of 19 protein motifs that allowed for the identification of particular clades. Sixteen SlMLO proteins from tomato were located in the phylogenetic tree and identified in relation to homologous sequences from other Solanaceae species. The obtained results could be useful for further work on the use of MLO proteins in the study of mildew resistance in Solanaceae and other plant families.

Genome-wide study of the GRAS gene family in Hibiscus hamabo Sieb. et Zucc and analysis of HhGRAS14-induced drought and salt stress tolerance in Arabidopsis

GRAS proteins are widely distributed plant-specific transcription factors. In this study, we identified 59 GRAS proteins (HhGRASs) from the genomic and transcriptomic datasets of Hibiscus hamabo Sieb. et Zucc. These proteins were phylogenetically divided into nine subfamilies. RNA-seq analysis revealed that most HhGRASs were expressed in response to abiotic stresses. Results from quantitative real-time PCR analysis of nine selected HhGRASs suggested that HhGRAS14 was significantly upregulated under multiple abiotic stresses; therefore, this gene was selected for further study. Silencing HhGRAS14 in H. hamabo reduced the tolerance to drought and salt stress, while overexpression in Arabidopsis thaliana significantly increased the tolerance to drought and salt and reduced the sensitivity to abscisic acid (ABA). In summary, we analyzed the GRAS family of proteins in semi-mangrove plants for the first time and identified a gene that responds to drought and salt stress, which provided the basis for a comprehensive analysis of GRAS genes and insight into the abiotic stress response mechanism in H. hamabo.

VvMYB1 potentially affects VvTOR gene expression by regulating VvTOR promoter and participates in glucose accumulation

MYB (v-myb avian myeloblastosis viral oncogene homolog) transcription factors make up one of the largest protein families in plants. The TOR (target of rapamycin) signaling network plays a pivotal role in sugar metabolism and plant growth. In this article, we utilized grape (Vitis vinifera) calli to explore the relationship between VvMYB1 and VvTOR. By using yeast one-hybrid and dual-luciferase reporter system, we speculated that there may be other proteins that help VvMYB1 and VvTOR promoter bond in grape calli, and the interaction action sites were located between the VvTOR 400-bp promoter fragment and the 1200-bp promoter fragment. The subcellular localization results suggest that VvMYB1 is found in the nucleus. Moreover, the expression level of VvTOR increased in the transgenic calli with overexpression of VvMYB1. These findings provide further evidence that VvMYB1 regulates VvTOR expression. We also found that overexpression of VvMYB1 increased glucose accumulation and affected expression of sugar-related genes. Our results suggest that there is a crosstalk between VvMYB1, VvTOR, and glucose accumulation.

Maize PPR278 Functions in Mitochondrial RNA Splicing and Editing.

Pentatricopeptide repeat (PPR) proteins are a large protein family in higher plants and play important roles during seed development. Most reported PPR proteins function in mitochondria. However, some PPR proteins localize to more than one organelle; functional characterization of these proteins remains limited in maize (Zea mays L.). Here, we cloned and analyzed the function of a P-subfamily PPR protein, PPR278. Loss-function of PPR278 led to a lower germination rate and other defects at the seedling stage, as well as smaller kernels compared to the wild type. PPR278 was expressed in all investigated tissues. Furthermore, we determined that PPR278 is involved in the splicing of two mitochondrial transcripts (nad2 intron 4 and nad5 introns 1 and 4), as well as RNA editing of C-to-U sites in 10 mitochondrial transcripts. PPR278 localized to the nucleus, implying that it may function as a transcriptional regulator during seed development. Our data indicate that PPR278 is involved in maize seed development via intron splicing and RNA editing in mitochondria and has potential regulatory roles in the nucleus.