title: Ethylene is required for both the initiation and progression of softening in pear (Pyrus communis L.) fruit.
abstract: In order to investigate the physiological role of ethylene in the initiation and subsequent progression of softening, pear fruit were treated with propylene, an analogue of ethylene or 1-methylcyclopropene (1-MCP), a gaseous inhibitor of ethylene action at the preclimacteric or ripening stages. The propylene treatment at the pre-ripe stage stimulated ethylene production and flesh softening while the 1-MCP treatment at the same stage markedly retarded the initiation of the ripening-related events. Moreover, 1-MCP treatment after the initiation of ripening markedly suppressed the subsequent flesh softening and ethylene production. These results clearly indicate that ethylene is not merely a by-product, but plays a crucial role in both the initiation and maintenance of regulating the softening process during ripening. The observations also suggest that ethylene in ripening is regulated entirely in an autocatalytic manner. The mRNA accumulation of pear polygalacturonases (PG) genes, PC-PG1 and PC-PG2, was in parallel with the pattern of fruit softening in both propylene and 1-MCP treatments. However, the expression pattern of pear endo-1,4-beta-D-glucanases (EGase) genes, PC-EG1 and PC-EG2, was not affected in both treatments. The results suggest that ethylene is required for PGs expression even in the late ripening stage, but not for EGases.
authors.affiliation: Graduate School of Natural Science and Technology, Okayama University, Tsushima, Okayama 700-8530, Japan.
authors.forename: Kyoko
authors.initials: K
authors.lastname: Hiwasa
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Kinugasa
authors.forename: Satomi
authors.initials: S
authors.lastname: Amano
authors.forename: Akiko
authors.initials: A
authors.lastname: Hashimoto
authors.forename: Ryohei
authors.initials: R
authors.lastname: Nakano
authors.forename: Akitsugu
authors.initials: A
authors.lastname: Inaba
authors.forename: Yasutaka
authors.initials: Y
authors.lastname: Kubo
mesh_terms: D000475:Alkenes / Q000494:pharmacology; D002480:Cellulase / Q000235:genetics* / Q000378:metabolism; D003001:Cloning, Molecular; D003521:Cyclopropanes / Q000494:pharmacology; D005030:Ethylenes / Q000378:metabolism*; D005638:Fruit / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D018507:Gene Expression Regulation, Developmental / Q000187:drug effects; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D007527:Isoenzymes / Q000235:genetics; D008969:Molecular Sequence Data; D010802:Phylogeny; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D011096:Polygalacturonase / Q000235:genetics* / Q000378:metabolism; D031989:Pyrus / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D012333:RNA, Messenger / Q000187:drug effects / Q000235:genetics / Q000378:metabolism
chemical_list: D000475:Alkenes; D003521:Cyclopropanes; D005030:Ethylenes; D007527:Isoenzymes; D010940:Plant Proteins; D012333:RNA, Messenger; C036216:ethylene; C013658:propylene; D011096:Polygalacturonase; D002480:Cellulase; C412563:1-methylcyclopropene