title: The role of the embryo and ethylene in avocado fruit mesocarp discoloration.
abstract: Chilling injury (CI) symptoms in avocado (Persea americana Mill.) fruit, expressed as mesocarp discoloration, were found to be associated with embryo growth and ethylene production during cold storage. In cvs Ettinger and Arad most mesocarp discoloration was located close to the base of the seed and was induced by ethylene treatment in seeded avocado fruit. However, ethylene did not increase mesocarp discoloration in seedless fruit stored at 5 degrees C. Application of ethylene to whole fruit induced embryo development inside the seed. It also induced seedling elongation when seeds were imbibed separately. Persea americana ethylene receptor (PaETR) gene expression and polyphenol oxidase activity were highest close to the base of the seed and decreased gradually toward the blossom end. By contrast, expressions of PaETR transcript and polyphenol oxidase activity in seedless avocado fruit were similar throughout the pulp at the base of the fruit. Application of the ethylene inhibitor, 1-methylcyclopropene, decreased mesocarp browning, embryo development, seedling growth, and ion leakage, and down-regulated polyphenol oxidase activity. The results demonstrate that ethylene-mediated embryo growth in whole fruit is involved in the mesocarp response to ethylene perception and the development of CI disorders.
authors.affiliation: Department of Postharvest Science of Fresh Produce, The Volcani Center, PO Box 6, Bet Dagan 50250, Israel.
authors.forename: Vera
authors.initials: V
authors.lastname: Hershkovitz
authors.forename: Haya
authors.initials: H
authors.lastname: Friedman
authors.forename: Eliezer E
authors.initials: EE
authors.lastname: Goldschmidt
authors.forename: Edna
authors.initials: E
authors.lastname: Pesis
mesh_terms: D004156:Catechol Oxidase / Q000378:metabolism; D003521:Cyclopropanes / Q000494:pharmacology; D004553:Electric Conductivity; D005030:Ethylenes / Q000378:metabolism* / Q000494:pharmacology; D005638:Fruit / Q000187:drug effects / Q000502:physiology*; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D018525:Germination / Q000187:drug effects; D008954:Models, Biological; D027421:Persea / Q000196:embryology* / Q000201:enzymology / Q000235:genetics / Q000502:physiology*; D010858:Pigmentation / Q000187:drug effects; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D036226:Seedlings / Q000187:drug effects / Q000254:growth & development; D012639:Seeds / Q000187:drug effects / Q000502:physiology*
chemical_list: D003521:Cyclopropanes; D005030:Ethylenes; D010940:Plant Proteins; D012333:RNA, Messenger; C036216:ethylene; D004156:Catechol Oxidase; C412563:1-methylcyclopropene