Molecular mechanism behind the involvement of apple flavonoid glycosyltransferase gene MdGT1 in the color of apple leaves

Flavonoids are a class of polyphenol compounds that are widespread in plants. They play an important role in plant growth and development. In this study, we found a mutant strain of M. baccata with yellow leaves (YL). Transcriptome sequencing revealed that it exhibited significant changes in the flavonoid metabolism pathway, which screening revealed was associated with a glycosyltransferase gene, MD09G1064900 (MdGT1). Analysis of its spatiotemporal expression showed that MdGT1 was mainly expressed in the stem and leaves, it means that MdGT1 may have a functional role in these parts. Real-time PCR and HPLC showed that MdGT1 was significantly upregulated by anthocyanin and exhibited strong anthocyaninase activity in vitro, respectively. An MdGT1 plant expression vector was constructed and overexpressed in apple fruit callus, resulting in a significant decrease of anthocyanin. Phenotypic observation also revealed that the MdGT1-overexpressing lines exhibited worse growth than the wild type after NaCl treatment, while they grew better upon the addition of exogenous anthocyanins. Moreover, real-time PCR and physiological data showed that MdGT1 is involved in salt stress and closely related to antioxidant pathways. Electrophoretic mobility shift assays (EMSA) and yeast one-hybrid experiments also proved that the transcription factor MdMYB88 is an upstream regulatory factor of MdGT1. The sequencing results revealed an amino acid insertion in an MdMYB88 HTH domain (between 77-131 amino acids) in the YL mutant strain. In conclusion, we identified a new apple glycosyltransferase gene, MdGT1, which may affect the color of apple leaves by glycosylating anthocyanins, and be regulated by the upstream transcription factor MdMYB88.The glycosyltransferases and their physiological significance in apple are largely unknown. Here we revealed that the MdMYB88-regulated apple glycosyltransferase gene MdGT1 plays a crucial role in the color of apple leaves and enhances plant tolerance to salt by antioxidant pathways via anthocyanin metabolism.

[1]  I Rovira,et al.  Nitric oxide , 2021, Reactions Weekly.

[2]  Guodong Yang,et al.  Function identification of MdTIR1 in apple root growth benefited from the predicted MdPPI network , 2020 .

[3]  Z. Xue,et al.  The control of red colour by a family of MYB transcription factors in octoploid strawberry (Fragaria × ananassa) fruits , 2019, Plant biotechnology journal.

[4]  J. Diffley,et al.  Mechanism of head-to-head MCM double-hexamer formation revealed by cryo-EM , 2019, Nature.

[5]  Ling Zhu,et al.  Identification and Characterization of MYB-bHLH-WD40 Regulatory Complex Members Controlling Anthocyanidin Biosynthesis in Blueberry Fruits Development , 2019, Genes.

[6]  M. Roxo,et al.  Phenolic Compounds from Populus alba L. and Salix subserrata Willd. (Salicaceae) Counteract Oxidative Stress in Caenorhabditis elegans , 2019, Molecules.

[7]  Bing-kai Hou,et al.  Identification and characterization of the first cytokinin glycosyltransferase from rice , 2019, Rice.

[8]  C. Maurel,et al.  Regulation of a plant aquaporin by a Casparian strip membrane domain protein-like. , 2019, Plant, cell & environment.

[9]  Mi-Young Kim,et al.  Improved expression of porcine epidemic diarrhea antigen by fusion with cholera toxin B subunit and chloroplast transformation in Nicotiana tabacum , 2019, Plant Cell, Tissue and Organ Culture (PCTOC).

[10]  M. Bink,et al.  High-quality, genome-wide SNP genotypic data for pedigreed germplasm of the diploid outbreeding species apple, peach, and sweet cherry through a common workflow , 2019, bioRxiv.

[11]  G. Glevarec,et al.  Genome-wide identification and biochemical characterization of the UGT88F subfamily in Malus x domestica Borkh. , 2019, Phytochemistry.

[12]  Dan Cheng,et al.  Nitric oxide contributes to methane-induced osmotic stress tolerance in mung bean , 2018, BMC Plant Biology.

[13]  B. Viollet,et al.  Exercise-induced molecular mechanisms promoting glycogen supercompensation in human skeletal muscle , 2018, Molecular metabolism.

[14]  T. Zhao,et al.  An atypical R2R3 MYB transcription factor increases cold hardiness by CBF-dependent and CBF-independent pathways in apple. , 2018, The New phytologist.

[15]  N. Seeram,et al.  Evaluation of Polyphenol Anthocyanin-Enriched Extracts of Blackberry, Black Raspberry, Blueberry, Cranberry, Red Raspberry, and Strawberry for Free Radical Scavenging, Reactive Carbonyl Species Trapping, Anti-Glycation, Anti-β-Amyloid Aggregation, and Microglial Neuroprotective Effects , 2018, International journal of molecular sciences.

[16]  F. Ma,et al.  Genome-wide identification of glycosyltransferases converting phloretin to phloridzin in Malus species. , 2017, Plant science : an international journal of experimental plant biology.

[17]  J. Cooney,et al.  Silencing a phloretin‐specific glycosyltransferase perturbs both general phenylpropanoid biosynthesis and plant development , 2017, The Plant journal : for cell and molecular biology.

[18]  D. Burgess.  Genetic engineering: CREATE-ing genome-wide designed mutations , 2016, Nature Reviews Genetics.

[19]  A. Minihane,et al.  The role of metabolism (and the microbiome) in defining the clinical efficacy of dietary flavonoids , 2016, The American journal of clinical nutrition.

[20]  Bing-kai Hou,et al.  The Arabidopsis UDP‐glycosyltransferases UGT79B2 and UGT79B3, contribute to cold, salt and drought stress tolerance via modulating anthocyanin accumulation , 2017, The Plant journal : for cell and molecular biology.

[21]  C. Fu,et al.  UDP-glycosyltransferase 72B1 catalyzes the glucose conjugation of monolignols and is essential for the normal cell wall lignification in Arabidopsis thaliana. , 2016, The Plant journal : for cell and molecular biology.

[22]  E. Lewinsohn,et al.  Identification and characterization of UDP-glucose:Phloretin 4'-O-glycosyltransferase from Malus x domestica Borkh. , 2016, Phytochemistry.

[23]  Bing-kai Hou,et al.  AtUGT76C2, an Arabidopsis cytokinin glycosyltransferase is involved in drought stress adaptation. , 2015, Plant science : an international journal of experimental plant biology.

[24]  Jianmei Wang,et al.  UDP-Glucosyltransferase71C5, a Major Glucosyltransferase, Mediates Abscisic Acid Homeostasis in Arabidopsis1[OPEN] , 2015, Plant Physiology.

[25]  E. Zažímalová,et al.  Kaempferol 3-O-rhamnoside-7-O-rhamnoside is an endogenous flavonol inhibitor of polar auxin transport in Arabidopsis shoots , 2013, The New phytologist.

[26]  Chao Gu,et al.  Deep RNA-Seq uncovers the peach transcriptome landscape , 2013, Plant Molecular Biology.

[27]  Bing-kai Hou,et al.  Ectopic Expression of Arabidopsis Glycosyltransferase UGT85A5 Enhances Salt Stress Tolerance in Tobacco , 2013, PloS one.

[28]  Peng Wang,et al.  A Na+/Ca2+ Exchanger-like Protein (AtNCL) Involved in Salt Stress in Arabidopsis* , 2012, The Journal of Biological Chemistry.

[29]  P. Pospíšil.  Molecular mechanisms of production and scavenging of reactive oxygen species by photosystem II. , 2012, Biochimica et biophysica acta.

[30]  Dirk Inzé,et al.  Perturbation of Indole-3-Butyric Acid Homeostasis by the UDP-Glucosyltransferase UGT74E2 Modulates Arabidopsis Architecture and Water Stress Tolerance[W] , 2010, Plant Cell.

[31]  C. Gachon,et al.  Transcriptional co-regulation of secondary metabolism enzymes in Arabidopsis: functional and evolutionary implications , 2005, Plant Molecular Biology.

[32]  B. Winkel-Shirley,et al.  It takes a garden. How work on diverse plant species has contributed to an understanding of flavonoid metabolism. , 2001, Plant physiology.

[33]  K. Vyacheslav,et al.  Shortening of life-time of the pair [P680+Pheo-] contributes to general inhibitory effect of dinoseb on electron transfer in PS-II. , 2000, Indian journal of biochemistry & biophysics.

[34]  H. Saedler,et al.  A new petunia flower colour generated by transformation of a mutant with a maize gene , 1987, Nature.