title: Abscission of flowers and floral organs is closely associated with alkalization of the cytosol in abscission zone cells.
abstract: In vivo changes in the cytosolic pH of abscission zone (AZ) cells were visualized using confocal microscopic detection of the fluorescent pH-sensitive and intracellularly trapped dye, 2',7'-bis-(2-carboxyethyl)-5(and-6)-carboxyfluorescein (BCECF), driven by its acetoxymethyl ester. A specific and gradual increase in the cytosolic pH of AZ cells was observed during natural abscission of flower organs in Arabidopsis thaliana and wild rocket (Diplotaxis tenuifolia), and during flower pedicel abscission induced by flower removal in tomato (Solanum lycopersicum Mill). The alkalization pattern in the first two species paralleled the acceleration or inhibition of flower organ abscission induced by ethylene or its inhibitor 1-methylcyclopropene (1-MCP), respectively. Similarly, 1-MCP pre-treatment of tomato inflorescence explants abolished the pH increase in AZ cells and pedicel abscission induced by flower removal. Examination of the pH changes in the AZ cells of Arabidopsis mutants defective in both ethylene-induced (ctr1, ein2, eto4) and ethylene-independent (ida, nev7, dab5) abscission pathways confirmed these results. The data indicate that the pH changes in the AZ cells are part of both the ethylene-sensitive and -insensitive abscission pathways, and occur concomitantly with the execution of organ abscission. pH can affect enzymatic activities and/or act as a signal for gene expression. Changes in pH during abscission could occur via regulation of transporters in AZ cells, which might affect cytosolic pH. Indeed, four genes associated with pH regulation, vacuolar H(+)-ATPase, putative high-affinity nitrate transporter, and two GTP-binding proteins, were specifically up-regulated in tomato flower AZ following abscission induction, and 1-MCP reduced or abolished the increased expression.
authors.affiliation: Department of Postharvest Science of Fresh Produce, Agricultural Research Organization (ARO), The Volcani Center, Bet-Dagan 5025001, Israel The Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, The Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot 7610001, Israel.
authors.forename: Srivignesh
authors.initials: S
authors.lastname: Sundaresan
authors.affiliation: Department of Postharvest Science of Fresh Produce, Agricultural Research Organization (ARO), The Volcani Center, Bet-Dagan 5025001, Israel.
authors.forename: Sonia
authors.initials: S
authors.lastname: Philosoph-Hadas
authors.affiliation: The Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, The Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot 7610001, Israel.
authors.forename: Joseph
authors.initials: J
authors.lastname: Riov
authors.affiliation: Department of Ornamental Horticulture, Agricultural Research Organization (ARO), The Volcani Center, Bet-Dagan 5025001, Israel.
authors.forename: Eduard
authors.initials: E
authors.lastname: Belausov
authors.affiliation: Department of Postharvest Science of Fresh Produce, Agricultural Research Organization (ARO), The Volcani Center, Bet-Dagan 5025001, Israel.
authors.forename: Betina
authors.initials: B
authors.lastname: Kochanek
authors.affiliation: Soybean Genomics and Improvement Laboratory, USDA-ARS, Beltsville, MD 20705, USA.
authors.forename: Mark L
authors.initials: ML
authors.lastname: Tucker
authors.affiliation: Department of Postharvest Science of Fresh Produce, Agricultural Research Organization (ARO), The Volcani Center, Bet-Dagan 5025001, Israel shimonm@volcani.agri.gov.il.
authors.forename: Shimon
authors.initials: S
authors.lastname: Meir
mesh_terms: D017360:Arabidopsis / Q000737:chemistry / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism; D019607:Brassicaceae / Q000737:chemistry / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism; D003521:Cyclopropanes / Q000378:metabolism; D003600:Cytosol / Q000737:chemistry / Q000187:drug effects* / Q000378:metabolism; D005030:Ethylenes / Q000378:metabolism; D035264:Flowers / Q000737:chemistry / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D006863:Hydrogen-Ion Concentration; D018551:Solanum lycopersicum / Q000737:chemistry / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism
chemical_list: D003521:Cyclopropanes; D005030:Ethylenes; D010940:Plant Proteins; C036216:ethylene; C412563:1-methylcyclopropene
keywords: Abscission zone; Arabidopsis mutants; alkalization; cytosol; ethylene; flower organs; pH regulation; tomato (Solanum lycopersicum); wild rocket (Diplotaxis tenuifolia).