Protein modification

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    Translating auxin responses into ovules, seeds and yield: Insight from Arabidopsis and the cereals
    Neil J Shirley, Matthew K. Aubert, Laura G. Wilkinson, Dayton C. Bird, Jorge Lora, Xiujuan Yang and Matthew R. Tucker
    J Integr Plant Biol    2019, 61 (3): 310-336.   DOI: 10.1111/jipb.12747
    Accepted: 26 November 2018
    Online available: 26 November 2018

    Abstract225)            English Version    Save
    Grain production in cereal crops depends on the stable formation of male and female gametes in the flower. In most angiosperms, the female gamete is produced from a germline located deep within the ovary, protected by several layers of maternal tissue, including the ovary wall, ovule integuments and nucellus. In the field, germline formation and floret fertility are major determinants of yield potential, contributing to traits such as seed number, weight and size. As such, stimuli affecting the timing and duration of reproductive phases, as well as the viability, size and number of cells within reproductive organs can significantly impact yield. One key stimulant is the phytohormone auxin, which influences growth and morphogenesis of female tissues during gynoecium development, gametophyte formation, and endosperm cellularization. In this review we consider the role of the auxin signaling pathway during ovule and seed development, first in the context of Arabidopsis and then in the cereals. We summarize the gene families involved and highlight distinct expression patterns that suggest a range of roles in reproductive cell specification and fate. This is discussed in terms of seed production and how targeted modification of different tissues might facilitate improvements.
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    Plant peroxisomes at the crossroad of NO and H2O2 metabolism
    Francisco J Corpas, Luis A. del Río and José M Palma
    J Integr Plant Biol    2019, 61 (7): 803-816.   DOI: 10.1111/jipb.12772
    Accepted: 04 January 2019
    Online available: 04 January 2019

    Abstract360)            English Version    Save
    Plant peroxisomes are subcellular compartments involved in many biochemical pathways during the life cycle of a plant but also in the mechanism of response against adverse environmental conditions. These organelles have an active nitro-oxidative metabolism under physiological conditions but this could be exacerbated under stress situations. Furthermore, peroxisomes have the capacity to proliferate and also undergo biochemical adaptations depending on the surrounding cellular status. An important characteristic of peroxisomes is that they have a dynamic metabolism of reactive nitrogen and oxygen species (RNS and ROS) which generates two key molecules, nitric oxide (NO) and hydrogen peroxide (H2O2). These molecules can exert signaling functions by means of post-translational modifications that affect the functionality of target molecules like proteins, peptides or fatty acids. This review provides an overview of the endogenous metabolism of ROS and RNS in peroxisomes with special emphasis on polyamine and uric acid metabolism as well as the possibility that these organelles could be a source of signal molecules involved in the functional interconnection with other subcellular compartments.
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    Hydrogen sulfide: A novel component in Arabidopsis peroxisomes which triggers catalase inhibition
    Francisco J. Corpas, Juan B. Barroso, Salvador González-Gordo, María A. Muñoz-Vargas and José M. Palma
    J Integr Plant Biol    2019, 61 (7): 871-883.   DOI: 10.1111/jipb.12779
    Accepted: 16 January 2019
    Online available: 16 January 2019

    Abstract418)            English Version    Save
    Plant peroxisomes have the capacity to generate different reactive oxygen and nitrogen species (ROS and RNS), such as H2O2, superoxide radical (O2· ), nitric oxide and peroxynitrite (ONOO). These organelles have an active nitro-oxidative metabolism which can be exacerbated by adverse stress conditions. Hydrogen sulfide (H2S) is a new signaling gasotransmitter which can mediate the posttranslational modification (PTM) persulfidation. We used Arabidopsis thaliana transgenic seedlings expressing cyan fluorescent protein (CFP) fused to a canonical peroxisome targeting signal 1 (PTS1) to visualize peroxisomes in living cells, as well as a specific fluorescent probe which showed that peroxisomes contain H2S. H2S was also detected in chloroplasts under glyphosate-induced oxidative stress conditions. Peroxisomal enzyme activities, including catalase, photorespiratory H2O2-generating glycolate oxidase (GOX) and hydroxypyruvate reductase (HPR), were assayed in vitro with a H2S donor. In line with the persulfidation of this enzyme, catalase activity declined significantly in the presence of the H2S donor. To corroborate the inhibitory effect of H2S on catalase activity, we also assayed pure catalase from bovine liver and pepper fruit-enriched samples, in which catalase activity was inhibited. Taken together, these data provide evidence of the presence of H2S in plant peroxisomes which appears to regulate catalase activity and, consequently, the peroxisomal H2O2 metabolism.
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    Protein S-Nitrosylation in plants: Current progresses and challenges
    Jian Feng, Lichao Chen and Jianru Zuo
    J Integr Plant Biol    2019, 61 (12): 1206-1223.   DOI: 10.1111/jipb.12780
    Accepted: 21 January 2019
    Online available: 21 January 2019

    Abstract325)      PDF (1790KB)(512)       English Version    Save
    Nitric oxide (NO) is an important signaling molecule regulating diverse biological processes in all living organisms. A major physiological function of NO is executed via protein S‐nitrosylation, a redox‐based posttranslational modification by covalently adding a NO molecule to a reactive cysteine thiol of a target protein. S‐nitrosylation is an evolutionarily conserved mechanism modulating multiple aspects of cellular signaling. During the past decade, significant progress has been made in functional characterization of S‐nitrosylated proteins in plants. Emerging evidence indicates that protein S‐nitrosylation is ubiquitously involved in the regulation of plant development and stress responses. Here we review current understanding on the regulatory mechanisms of protein S‐nitrosylation in various biological processes in plants and highlight key challenges in this field.
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    The plant N-degron pathways of ubiquitin‐mediated proteolysis
    Michael John Holdsworth, Jorge Vicente, Gunjan Sharma, Mohamad Abbas and Agata Zubrycka
    J Integr Plant Biol    2020, 62 (1): 70-89.   DOI: 10.1111/jipb.12882
    Accepted: 22 October 2019
    Online available: 22 October 2019

    Abstract377)      PDF (3767KB)(240)       English Version    Save

    The amino‐terminal residue of a protein (or amino‐terminus of a peptide following protease cleavage) can be an important determinant of its stability, through the Ubiquitin Proteasome System associated N‐degron pathways. Plants contain a unique combination of N‐degron pathways (previously called the N‐end rule pathways) E3 ligases, PROTEOLYSIS (PRT)6 and PRT1, recognizing non‐overlapping sets of amino‐terminal residues, and others remain to be identified. Although only very few substrates of PRT1 or PRT6 have been identified, substrates of the oxygen and nitric oxide sensing branch of the PRT6 N‐degron pathway include key nuclear‐located transcription factors (ETHYLENE RESPONSE FACTOR VIIs and LITTLE ZIPPER 2) and the histone‐modifying Polycomb Repressive Complex 2 component VERNALIZATION 2. In response to reduced oxygen or nitric oxide levels (and other mechanisms that reduce pathway activity) these stabilized substrates regulate diverse aspects of growth and development, including response to flooding, salinity, vernalization (cold‐induced flowering) and shoot apical meristem function. The N‐degron pathways show great promise for use in the improvement of crop performance and for biotechnological applications. Upstream proteases, components of the different pathways and associated substrates still remain to be identified and characterized to fully appreciate how regulation of protein stability through the amino‐terminal residue impacts plant biology.

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    A WRKY transcription factor confers aluminum tolerance via regulation of cell wall modifying genes
    Chun Xiao Li, Jing Ying Yan, Jiang Yuan Ren, Li Sun, Chen Xu, Gui Xin Li, Zhong Jie Ding and Shao Jian Zheng
    J Integr Plant Biol    2020, 62 (8): 1176-1192.   DOI: 10.1111/jipb.12888
    Accepted: 15 November 2019
    Online available: 15 November 2019

    Modification of cell wall properties has been considered as one of the determinants that confer aluminum (Al) tolerance in plants, while how cell wall modifying processes are regulated remains elusive. Here, we present a WRKY transcription factor WRKY47 involved in Al tolerance and root growth. Lack of WRKY47 significantly reduces, while overexpression of it increases Al tolerance. We show that lack of WRKY47 substantially affects subcellular Al distribution in the root, with Al content decreased in apoplast and increased in symplast, which is attributed to the reduced cell wall Al‐binding capacity conferred by the decreased content of hemicellulose I in the wrky47‐1 mutant. Based on microarray, real time‐quantitative polymerase chain reaction and chromatin immunoprecipitation assays, we further show that WRKY47 directly regulates the expression of EXTENSIN‐LIKE PROTEIN (ELP ) and XYLOGLUCAN ENDOTRANSGLUCOSYLASE‐HYDROLASES17 (XTH17 ) responsible for cell wall modification. Increasing the expression of ELP and XTH17 rescued Al tolerance as well as root growth in wrky47‐1 mutant. In summary, our results demonstrate that WRKY47 is required for root growth under both normal and Al stress conditions via direct regulation of cell wall modification genes, and that the balance of Al distribution between root apoplast and symplast conferred by WRKY47 is important for Al tolerance.

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    Autophagy in plants: Physiological roles and post‐translational regulation
    Hua Qi, Fan-Nv Xia and Shi Xiao
    J Integr Plant Biol    2021, 63 (1): 161-179.   DOI: 10.1111/jipb.12941
    Accepted: 23 April 2020
    Online available: 23 April 2020

    Abstract406)            English Version    Save
    In eukaryotes, autophagy helps maintain cellular homeostasis by degrading and recycling cytoplasmic materials via a tightly regulated pathway. Over the past few decades, significant progress has been made towards understanding the physiological functions and molecular regulation of autophagy in plant cells. Increasing evidence indicates that autophagy is essential for plant responses to several developmental and environmental cues, functioning in diverse processes such as senescence, male fertility, root meristem maintenance, responses to nutrient starvation, and biotic and abiotic stress. Recent studies have demonstrated that, similar to nonplant systems, the modulation of core proteins in the plant autophagy machinery by posttranslational modifications such as phosphorylation, ubiquitination, lipidation, S‐sulfhydration, S‐nitrosylation, and acetylation is widely involved in the initiation and progression of autophagy. Here, we provide an overview of the physiological roles and posttranslational regulation of autophagy in plants.
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    PUB22 and PUB23 U-box E3 ubiquitin ligases negatively regulate 26S proteasome activity under proteotoxic stress conditions
    Min Yong Ahn, Dong Hye Seo and Woo Taek Kim
    J Integr Plant Biol    2022, 64 (3): 625-631.   DOI: 10.1111/jipb.13209
    Accepted: 29 December 2021
    Online available: 29 December 2021

    Abstract239)            English Version    Save

    The mechanism regulating proteasomal activity under proteotoxic stress conditions remains unclear. Here, we showed that arsenite-induced proteotoxic stress resulted in upregulation of Arabidopsis homologous PUB22 and PUB23 U-box E3 ubiquitin ligases and that pub22pub23 double mutants displayed arsenite-insensitive seed germination and root growth phenotypes. PUB22/PUB23 downregulated 26S proteasome activity by promoting the dissociation of the 19S regulatory particle from the holo-proteasome complex, resulting in intracellular accumulation of UbG76V-GFP, an artificial substrate of the proteasome complex, and insoluble poly-ubiquitinated proteins. These results suggest that PUB22/PUB23 play a critical role in arsenite-induced proteotoxic stress response via negative regulation of 26S proteasome integrity.

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    Cited: WebOfScience(4)
      
    Molecular and structural characterization of a promiscuous chalcone synthase from the fern species Stenoloma chusanum
    Rong Ni, Meng Niu, Jie Fu, Hui Tan, Ting‐Ting Zhu, Jing Zhang, Hong‐Xiang Lou, Peng Zhang, Jian‐Xu Li and Ai‐Xia Cheng
    J Integr Plant Biol    2022, 64 (10): 1935-1951.   DOI: 10.1111/jipb.13335
    Accepted: 06 September 2022
    Online available: 06 September 2022

    Abstract182)            English Version    Save
    The key enzymes involved in the flavonoid biosynthesis pathway have been extensively studied in seed plants, but relatively less in ferns. In this study, two 4-Coumarate: coenzyme A ligases (Sc4CL1 and Sc4CL2) and one novel chalcone synthase (ScCHS1) were functionally characterized by mining the Stenoloma chusanum transcriptome database. Recombinant Sc4CLs were able to esterify various hydroxycinnamic acids to corresponding acyl-coenzyme A (CoA). ScCHS1 could catalyze p-coumaroyl-CoA, cinnamoyl-CoA, caffeoyl-CoA, and feruloyl-CoA to form naringenin, pinocembrin, eriodictyol, and homoeriodictyol, respectively. Moreover, enzymatic kinetics studies revealed that the optimal substrates of ScCHS1 were feruloyl-CoA and caffeoyl-CoA, rather than p-coumaroyl-CoA, which was substantially different from the common CHSs. Crystallographic and site-directed mutagenesis experiments indicated that the amino acid residues, Leu87, Leu97, Met165, and Ile200, located in the substrate-binding pocket near the B-ring of products, could exert a significant impact on the unique catalytic activity of ScCHS1. Furthermore, overexpression of ScCHS1 in tt4 mutants could partially rescue the mutant phenotypes. Finally, ScCHS1 and Sc4CL1 were used to synthesize flavanones and flavones with multi-substituted hydroxyl and methoxyl B-ring in Escherichia coli, which can effectively eliminate the need for the cytochrome P450 hydroxylation/O-methyltransferase from simple phenylpropanoid acids. In summary, the identification of these important Stenoloma enzymes provides a springboard for the future production of various flavonoids in E. coli.
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    Protein ubiquitination in plant peroxisomes
    Delara Akhter, Yuchan Zhang, Jianping Hu and Ronghui Pan
    J Integr Plant Biol    2023, 65 (2): 371-380.   DOI: 10.1111/jipb.13346
    Accepted: 17 August 2022
    Online available: 17 August 2022

    Abstract205)            English Version    Save
    Protein ubiquitination regulates diverse cellular processes in eukaryotic organisms, from growth and development to stress response. Proteins subjected to ubiquitination can be found in virtually all subcellular locations and organelles, including peroxisomes, single-membrane and highly dynamic organelles ubiquitous in eukaryotes. Peroxisomes contain metabolic functions essential to plants and animals such as lipid catabolism, detoxification of reactive oxygen species (ROS), biosynthesis of vital hormones and cofactors, and photorespiration. Plant peroxisomes possess a complex proteome with functions varying among different tissue types and developmental stages, and during plant response to distinct environmental cues. However, how these diverse functions are regulated at the post-translational level is poorly understood, especially in plants. In this review, we summarized current knowledge of the involvement of protein ubiquitination in peroxisome protein import, remodeling, pexophagy, and metabolism, focusing on plants, and referencing discoveries from other eukaryotic systems when relevant. Based on previous ubiquitinomics studies, we compiled a list of 56 ubiquitinated Arabidopsis peroxisomal proteins whose functions are associated with all the major plant peroxisomal metabolic pathways. This discovery suggests a broad impact of protein ubiquitination on plant peroxisome functions, therefore substantiating the need to investigate this significant regulatory mechanism in peroxisomes at more depths.
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    Cited: WebOfScience(2)
      
    Dynamic regulation of DNA methylation and histone modifications in response to abiotic stresses in plants
    Yutong Liu, Jie Wang, Bao Liu and Zheng-Yi Xu
    J Integr Plant Biol    2022, 64 (12): 2252-2274.   DOI: 10.1111/jipb.13368
    Accepted: 23 September 2022
    Online available: 23 September 2022

    Abstract246)            English Version    Save

    DNA methylation and histone modification are evolutionarily conserved epigenetic modifications that are crucial for the expression regulation of abiotic stress-responsive genes in plants. Dynamic changes in gene expression levels can result from changes in DNA methylation and histone modifications. In the last two decades, how epigenetic machinery regulates abiotic stress responses in plants has been extensively studied. Here, based on recent publications, we review how DNA methylation and histone modifications impact gene expression regulation in response to abiotic stresses such as drought, abscisic acid, high salt, extreme temperature, nutrient deficiency or toxicity, and ultraviolet B exposure. We also review the roles of epigenetic mechanisms in the formation of transgenerational stress memory. We posit that a better understanding of the epigenetic underpinnings of abiotic stress responses in plants may facilitate the design of more stress-resistant or -resilient crops, which is essential for coping with global warming and extreme environments.

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    SUMOylation facilitates the assembly of a Nuclear Factor-Y complex to enhance thermotolerance in Arabidopsis
    Junwen Huang, Junjie Huang, Qiyi Feng, Yaqiao Shi, Feige Wang, Kaiyong Zheng, Qize Huang, Jieming Jiang, Siyi Luo, Yun Xie, Danlu Han, Jianbin Lai and Chengwei Yang
    J Integr Plant Biol    2023, 65 (3): 692-702.   DOI: 10.1111/jipb.13396
    Accepted: 25 October 2022
    Online available: 25 October 2022

    Abstract279)            English Version    Save
    Heat stress (HS) has serious negative effects on plant development and has become a major threat to agriculture. A rapid transcriptional regulatory cascade has evolved in plants in response to HS. Nuclear Factor-Y (NF-Y) complexes are critical for this mechanism, but how NF-Y complexes are regulated remains unclear. In this study, we identified NF-YC10 (NF-Y subunit C10), a central regulator of the HS response in Arabidopsis thaliana, as a substrate of SUMOylation, an important post-translational modification. Biochemical analysis showed that the SUMO ligase SIZ1 (SAP AND MIZ1 DOMAIN-CONTAINING LIGASE1) interacts with NF-YC10 and enhances its SUMOylation during HS. The SUMOylation of NF-YC10 facilitates its interaction with and the nuclear translocation of NF-YB3, in which the SUMO interaction motif (SIM) is essential for its efficient association with NF-YC10. Further functional analysis indicated that the SUMOylation of NF-YC10 and the SIM of NF-YB3 are critical for HS-responsive gene expression and plant thermotolerance. These findings uncover a role for the SIZ1-mediated SUMOylation of NF-YC10 in NF-Y complex assembly under HS, providing new insights into the role of a post-translational modification in regulating transcription during abiotic stress responses in plants.
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    Plasma membrane-localized Hsp40/DNAJ chaperone protein facilitates OsSUVH7-OsBAG4-OsMYB106 transcriptional complex formation for OsHKT1;5 activation
    Yutong Liu, Mengting Li, Jinlei Yu, Ao Ma, Jie Wang, Dae-Jin Yun, Zheng-Yi Xu
    J Integr Plant Biol    2023, 65 (1): 265-279.   DOI: 10.1111/jipb.13403
    Accepted: 11 November 2022
    Online available: 11 November 2022

    The salinization of irrigated land affects agricultural productivity. HIGH-AFFINITY POTASSIUM (K+) TRANSPORTER 1;5 (OsHKT1;5)-dependent sodium (Na+) transport is a key salt tolerance mechanism during rice growth and development. Using a previously generated high-throughput activation tagging-based T-DNA insertion mutant pool, we isolated a mutant exhibiting salt stress-sensitive phenotype, caused by a reduction in OsHKT1;5 transcripts. The salt stress-sensitive phenotype of this mutant results from the loss of function of OsDNAJ15, which encodes plasma membrane-localized heat shock protein 40 (Hsp40). osdnaj15 loss-of-function mutants show decreased plant height, increased leaf angle, and reduced grain number caused by shorter panicle length and fewer branches. On the other h'and, OsDNAJ15-overexpression plants showed salt stress-tolerant phenotypes. Intriguingly, salt stress facilitates the nuclear relocation of OsDNAJ15 so that it can interact with OsBAG4, and OsDNAJ15 and OsBAG4 synergistically facilitate the DNA-binding activity of OsMYB106 to positively regulate the expression of OsHKT1;5. Overall, our results reveal a novel function of plasma membrane-localized Hsp40 protein in modulating, alongside chaperon regulator OsBAG4, transcriptional regulation under salinity stress tolerance.
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    The safflower MBW complex regulates HYSA accumulation through degradation by the E3 ligase CtBB1
    Yingqi Hong, Yanxi Lv, Jianyi Zhang, Naveed Ahmad, Xiaokun Li, Na Yao, Xiuming Liu and Haiyan Li
    J Integr Plant Biol    2023, 65 (5): 1277-1296.   DOI: 10.1111/jipb.13444
    Accepted: 27 March 2023
    Online available: 27 March 2023

    Abstract239)            English Version    Save
    The regulatory mechanism of the MBW (MYB‐ bHLH‐WD40) complex in safflower (Carthamus tinctorius) remains unclear. In the present study, we show that the separate overexpression of the genes CtbHLH41, CtMYB63, and CtWD40‐6 in Arabidopsis thaliana increased anthocyanin and procyanidin contents in the transgenic plants and partially rescued the trichome reduction phenotype of the corresponding bhlh41, myb63, and wd40‐6 single mutants. Overexpression of CtbHLH41, CtMYB63, or CtWD40‐6 in safflower significantly increased the content of the natural pigment hydroxysafflor yellow A (HYSA) and negatively regulated safflower petal size. Yeast‐two‐hybrid, functional, and genetic assays demonstrated that the safflower E3 ligase CtBB1 (BIG BROTHER 1) can ubiquitinate CtbHLH41, marking it for degradation through the 26S proteasome and negatively regulating flavonoid accumulation. CtMYB63/CtWD40‐6 enhanced the transcriptional activity of CtbHLH41 on the CtDFR (dihydroflavonol 4‐reductase) promoter. We propose that the MBW‐CtBB1 regulatory module may play an important role in coordinating HYSA accumulation with other response mechanisms.
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    Heteromerization of short‐chain trans‐prenyltransferase controls precursor allocation within a plastidial terpenoid network
    Yihua Ma, Qingwen Chen, Yaoyao Wang, Fengxia Zhang, Chengyuan Wang and Guodong Wang
    J Integr Plant Biol    2023, 65 (5): 1170-1182.   DOI: 10.1111/jipb.13454
    Accepted: 15 March 2023
    Online available: 15 March 2023

    Abstract143)            English Version    Save
    Terpenes are the largest and most diverse class of plant specialized metabolites. Sesterterpenes (C25), which are derived from the plastid methylerythritol phosphate pathway, were recently characterized in plants. In Arabidopsis thaliana, four genes encoding geranylfarnesyl diphosphate synthase (GFPPS) (AtGFPPS1 to 4) are responsible for the production of GFPP, which is the common precursor for sesterterpene biosynthesis. However, the interplay between sesterterpenes and other known terpenes remain elusive. Here, we first provide genetic evidence to demonstrate that GFPPSs are responsible for sesterterpene production in Arabidopsis. Blockage of the sesterterpene pathway at the GFPPS step increased the production of geranylgeranyl diphosphate (GGPP)-derived terpenes. Interestingly, co-expression of sesterTPSs in GFPPS-OE (overexpression) plants rescued the phenotypic changes of GFPPS-OE plants by restoring the endogenous GGPP. We further demonstrated that, in addition to precursor (DMAPP/IPP) competition by GFPPS and GGPP synthase (GGPPS) in plastids, GFPPS directly decreased the activity of GGPPS through protein-protein interaction, ultimately leading to GGPP deficiency in planta. Our study provides a new regulatory mechanism of the plastidial terpenoid network in plant cells.
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    Phosphorylation of the LCB1 subunit of Arabidopsis serine palmitoyltransferase stimulates its activity and modulates sphingolipid biosynthesis
    Yuan Li, Hanwei Cao, Tingting Dong, Xiaoke Wang, Liang Ma, Kun Li, Huiqiang Lou, Chun-Peng Song and Dongtao Ren
    J Integr Plant Biol    2023, 65 (6): 1585-1601.   DOI: 10.1111/jipb.13461
    Accepted: 04 February 2023
    Online available: 04 February 2023

    Abstract262)            English Version    Save
    Sphingolipids are the structural components of membrane lipid bilayers and act as signaling molecules in many cellular processes. Serine palmitoyltransferase (SPT) is the first committed and rate-limiting enzyme in the de novo sphingolipids biosynthetic pathway. The core SPT enzyme is a heterodimer consisting of LONG-CHAIN BASE1 (LCB1) and LCB2 subunits. SPT activity is inhibited by orosomucoid proteins and stimulated by small subunits of SPT (ssSPTs). However, whether LCB1 is modified and how such modification might regulate SPT activity have to date been unclear. Here, we show that activation of MITOGEN-ACTIVATED PROTEIN KINASE 3 (MPK3) and MPK6 by upstream MKK9 and treatment with Flg22 (a pathogen-associated molecular pattern) increases SPT activity and induces the accumulation of sphingosine long-chain base t18:0 in Arabidopsis thaliana, with activated MPK3 and MPK6 phosphorylating AtLCB1. Phosphorylation of AtLCB1 strengthened its binding with AtLCB2b, promoted its binding with ssSPTs, and stimulated the formation of higher order oligomeric and active SPT complexes. Our findings therefore suggest a novel regulatory mechanism for SPT activity.
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    DIW1 encoding a clade I PP2C phosphatase negatively regulates drought tolerance by de-phosphorylating TaSnRK1.1 in wheat
    Jingyi Wang, Chaonan Li, Long Li, Lifeng Gao, Ge Hu, Yanfei Zhang, Matthew P. Reynolds, Xueyong Zhang, Jizeng Jia, Xinguo Mao and Ruilian Jing
    J Integr Plant Biol    2023, 65 (8): 1918-1936.   DOI: 10.1111/jipb.13504
    Accepted: 09 May 2023
    Online available: 09 May 2023

    Abstract332)            English Version    Save
    Drought seriously impacts wheat production (Triticum aestivum L.), while the exploitation and utilization of genes for drought tolerance are insufficient. Leaf wilting is a direct reflection of drought tolerance in plants. Clade A PP2Cs are abscisic acid (ABA) co-receptors playing vital roles in the ABA signaling pathway, regulating drought response. However, the roles of other clade PP2Cs in drought tolerance, especially in wheat, remain largely unknown. Here, we identified a gain-of-function drought-induced wilting 1 (DIW1) gene from the wheat Aikang 58 mutant library by map-based cloning, which encodes a clade I protein phosphatase 2C (TaPP2C158) with enhanced protein phosphatase activity. Phenotypic analysis of overexpression and CRISPR/Cas9 mutant lines demonstrated that DIW1/TaPP2C158 is a negative regulator responsible for drought resistance. We found that TaPP2C158 directly interacts with TaSnRK1.1 and de-phosphorylates it, thus inactivating the TaSnRK1.1–TaAREB3 pathway. TaPP2C158 protein phosphatase activity is negatively correlated with ABA signaling. Association analysis suggested that C-terminal variation of TaPP2C158 changing protein phosphatase activity is highly correlated with the canopy temperature, and seedling survival rate under drought stress. Our data suggest that the favorable allele with lower phosphatase activity of TaPP2C158 has been positively selected in Chinese breeding history. This work benefits us in understanding the molecular mechanism of wheat drought tolerance, and provides elite genetic resources and molecular markers for improving wheat drought tolerance.
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    The E3 ubiquitin ligase SINA1 and the protein kinase BIN2 cooperatively regulate PHR1 in apple anthocyanin biosynthesis
    Jian‐Ping An, Hong‐Liang Li, Zhi‐Ying Liu, Da‐Ru Wang, Chun‐Xiang You and Yuepeng Han
    J Integr Plant Biol    2023, 65 (9): 2175-2193.   DOI: 10.1111/jipb.13538
    Accepted: 05 June 2023
    Online available: 05 June 2023

    Abstract263)            English Version    Save
    PHR1 (PHOSPHATE STARVATION RESPONSE1) plays key roles in the inorganic phosphate (Pi) starvation response and in Pi deficiency-induced anthocyanin biosynthesis in plants. However, the post-translational regulation of PHR1 is unclear, and the molecular basis of PHR1-mediated anthocyanin biosynthesis remains elusive. In this study, we determined that MdPHR1 was essential for Pi deficiency-induced anthocyanin accumulation in apple (Malus×domestica). MdPHR1 interacted with MdWRKY75, a positive regulator of anthocyanin biosynthesis, to enhance the MdWRKY75-activated transcription of MdMYB1, leading to anthocyanin accumulation. In addition, the E3 ubiquitin ligase SEVEN IN ABSENTIA1 (MdSINA1) negatively regulated MdPHR1-promoted anthocyanin biosynthesis via the ubiquitination-mediated degradation of MdPHR1. Moreover, the protein kinase apple BRASSINOSTEROID INSENSITIVE2 (MdBIN2) phosphorylated MdPHR1 and positively regulated MdPHR1-mediated anthocyanin accumulation by attenuating the MdSINA1-mediated ubiquitination degradation of MdPHR1. Taken together, these findings not only demonstrate the regulatory role of MdPHR1 in Pi starvation induced anthocyanin accumulation, but also provide an insight into the post-translational regulation of PHR1.
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