Inhibition of ethylene in the presence of leaves in stage II persimmon (Diospyros/ca/c/Thunb.) fruit under wounding treatment on a tree

摘要

Reports of 'tree factors' identified that some climacteric fruit on tree receive inhibitors of ripening or ethylene synthesis from leaves of the parent plant. The present study investigated the nature of these 'tree ethylene inhibitory factors' in stage II (immature) persimmon fruit at the molecular level. Fruit softening ratio and ethylene production of persimmon under wounding treatment with or without attachment of leaves to the fruit-bearing shoot were monitored. Evolution of these physiologicalitems tended to be inhibited by the attachment of leaves as contrast to that without leaves. The expression of three ACC synthase (ACS) genes, DkACSl, DkACS2 and DkACS3, and two ACC oxidase (ACO) genes, DkACOl and DkAC02 were investigated. Larger accumulation of DK-ACS2 transcripts activated by wound stress in the core section was markedly inhibited in the presence of leaf attachment. The accumulation of DK-ACS3, DK-ACOl and DK-AC02 transcripts in the core section, especially DK-ACS3 in the layer adjoining the calyx, was markedly inhibited by the attachment of leaves. These three genes exhibited rapid increase in mRNA accumulation 2 days after treatments, which might be directly induced by the previous large rise of ethylene production in the calyx. Inhibitory effects of 'the tree factor' on ethylene synthesis was obvious in fruit core rather than in pulp section.