title: Proteomic analysis of stress-related proteins in transgenic broccoli harboring a gene for cytokinin production during postharvest senescence.
abstract: Our previous study revealed a cytokinin-related retardation of post-harvest floret yellowing in transgenic broccoli (Brassica oleracea var. italica) that harbored the bacterial isopentenyltransferase (ipt) gene. We aimed to investigate the underlining mechanism of this delayed post-harvest senescence. We used 2D electrophoresis and liquid chromatography-electrospray ionization-mass spectrometry/mass spectrometry for a proteomics analysis of heads of ipt-transgenic and non-transgenic inbred lines of broccoli at harvest and after four days post-harvest storage. At harvest, we found an accumulation of stress-responsive proteins involved in maintenance of protein folding (putative protein disulfide isomerase, peptidyl-prolyl cis-trans isomerase and chaperonins), scavenging of reactive oxygen species (Mn superoxide dismutase), and stress protection [myrosinase-binding protein, jasmonate inducible protein, dynamin-like protein, NADH dehydrogenase (ubiquinone) Fe-S protein 1 and stress-inducible tetratricopeptide repeat-containing protein]. After four days' post-harvest storage of non-transgenic broccoli florets, the levels of proteins involved in protein folding and carbon fixation were decreased, which indicates cellular degradation and a change in metabolism toward senescence. In addition, staining for antioxidant enzyme activity of non-transgenic plants after post-harvest storage revealed a marked decrease in activity of Fe-superoxide dismutase and ascorbate peroxidase. Thus, the accumulation of stress-responsive proteins and antioxidant enzyme activity in ipt-transgenic broccoli are most likely associated with retardation of post-harvest senescence.
authors.affiliation: Institute of Plant and Microbial Biology, Academia Sinica, Nankang, Taipei 11529, Taiwan.
authors.forename: Mao-Sen
authors.initials: MS
authors.lastname: Liu
authors.forename: Hui-Chun
authors.initials: HC
authors.lastname: Li
authors.forename: You-Min
authors.initials: YM
authors.lastname: Chang
authors.forename: Min-Tze
authors.initials: MT
authors.lastname: Wu
authors.forename: Long-Fang Oliver
authors.initials: LF
authors.lastname: Chen
mesh_terms: D019883:Alkyl and Aryl Transferases / Q000378:metabolism; D001937:Brassica / Q000235:genetics* / Q000378:metabolism*; D003583:Cytokinins / Q000096:biosynthesis* / Q000235:genetics*; D035264:Flowers / Q000235:genetics / Q000378:metabolism; D015971:Gene Expression Regulation, Enzymologic; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D014644:Genetic Variation; D006360:Heat-Shock Proteins / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D030821:Plants, Genetically Modified / Q000235:genetics / Q000378:metabolism; D040901:Proteomics / Q000379:methods; D013624:Taiwan; D013997:Time Factors
chemical_list: D003583:Cytokinins; D006360:Heat-Shock Proteins; D019883:Alkyl and Aryl Transferases; C024274:adenylate isopentenyltransferase