JXB Advance Access originally published online on September 12, 2006
Journal of Experimental Botany 2006 57(14):3679-3686; doi:10.1093/jxb/erl129
RESEARCH PAPER |
Effect of girdling above the abscission zone of fruit on Bartlett pear ripening on the tree

1Faculty of Agriculture, Yamagata University, Tsuruoka 997-8555, Japan
2JST (Japan Science and Technology Corporation) Regional Joint Research Project of Yamagata Prefecture, Yamagata 991-0043, Japan
* To whom correspondence should be addressed. E-mail: mhideki{at}tds1.tr.yamagata-u.ac.jp
Pear fruit usually soften and develop a melting texture when harvested at the mature green stage and ripened. The reason why the fruit does not fully ripen on the tree is unknown. To clarify this, our attention was directed to the continuous supply of assimilates and/or other substances into the fruit via phloem transport. To determine the effect of inhibiting phloem transport on fruit ripening on the tree, a girdling treatment was applied to the branch above the abscission zone of Bartlett pear (Pyrus communis L.). Girdling significantly enhanced the ethylene production of fruit on day 12 compared with control fruit. Fruit softening was also stimulated by girdling. On day 8, flesh firmness was similar in treated fruit on the tree and in fruit off the tree, and was significantly lower than that of untreated fruit on the tree. The patterns of transcript accumulation for the ethylene biosynthetic [1-aminocyclopropane-1-carboxylate (ACC) synthase (PcACS) and ACC oxidase (PcACO)] and polygalacturonase (PcPG1 and PcPG3) genes showed good correspondence with ethylene production and fruit softening, respectively. Thus, fruit ripening on the tree was stimulated via ethylene by girdling on the branch above the abscission zone of fruit to interrupt phloem transport. Assimilates and/or other substances in phloem sap may prevent fruit ripening on the tree.
Key words: Ethylene, fruit softening, girdling, Pyrus communis, ripening