title: Reducing AsA leads to leaf lesion and defence response in knock-down of the AsA biosynthetic enzyme GDP-D-mannose pyrophosphorylase gene in tomato plant.
abstract: As a vital antioxidant, L-ascorbic acid (AsA) affects diverse biological processes in higher plants. Lack of AsA in cell impairs plant development. In the present study, we manipulated a gene of GDP-mannose pyrophosphorylase which catalyzes the conversion of D-mannose-1-P to GDP-D-mannose in AsA biosynthetic pathway and found out the phenotype alteration of tomato. In the tomato genome, there are four members of GMP gene family and they constitutively expressed in various tissues in distinct expression patterns. As expected, over-expression of SlGMP3 increased total AsA contents and enhanced the tolerance to oxidative stress in tomato. On the contrary, knock-down of SlGMP3 significantly decreased AsA contents below the threshold level and altered the phenotype of tomato plants with lesions and further senescence. Further analysis indicated the causes for this symptom could result from failing to instantly deplete the reactive oxygen species (ROS) as decline of free radical scavenging activity. More ROS accumulated in the leaves and then triggered expressions of defence-related genes and mimic symptom occurred on the leaves similar to hypersensitive responses against pathogens. Consequently, the photosynthesis of leaves was dramatically fallen. These results suggested the vital roles of AsA as an antioxidant in leaf function and defence response of tomato.
authors.affiliation: The Key Laboratory of Horticultural Plant Biology, Ministry of Education, Huazhong Agricultural University, Wuhan, China.
authors.forename: Chanjuan
authors.initials: C
authors.lastname: Zhang
authors.forename: Bo
authors.initials: B
authors.lastname: Ouyang
authors.forename: Changxian
authors.initials: C
authors.lastname: Yang
authors.forename: Xiaohui
authors.initials: X
authors.lastname: Zhang
authors.forename: Hui
authors.initials: H
authors.lastname: Liu
authors.forename: Yuyang
authors.initials: Y
authors.lastname: Zhang
authors.forename: Junhong
authors.initials: J
authors.lastname: Zhang
authors.forename: Hanxia
authors.initials: H
authors.lastname: Li
authors.forename: Zhibiao
authors.initials: Z
authors.lastname: Ye
mesh_terms: D001205:Ascorbic Acid / Q000096:biosynthesis*; D005638:Fruit / Q000201:enzymology / Q000235:genetics / Q000276:immunology; D018506:Gene Expression Regulation, Plant; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism; D018551:Solanum lycopersicum / Q000201:enzymology / Q000235:genetics / Q000276:immunology*; D009713:Nucleotidyltransferases / Q000235:genetics / Q000378:metabolism*; D009928:Organ Specificity; D010788:Photosynthesis / Q000235:genetics; D018515:Plant Leaves / Q000201:enzymology / Q000235:genetics / Q000276:immunology; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D018517:Plant Roots / Q000201:enzymology / Q000235:genetics / Q000276:immunology; D018547:Plant Stems / Q000201:enzymology / Q000235:genetics / Q000276:immunology; D030821:Plants, Genetically Modified; D044224:Pseudomonas syringae / Q000254:growth & development
chemical_list: D007527:Isoenzymes; D010940:Plant Proteins; D009713:Nucleotidyltransferases; C026917:mannose 1-phosphate guanylyltransferase; D001205:Ascorbic Acid