Chitinases of the grapevine ( Vitis vinifera L.): five isoforms induced in leaves by salicylic acid are constitutively expressed in other tissues

Abstract

Using a colored substrate assay, chitinase activity was detected in various grapevine ( Vitis vinifera L.) tissues such as winter-resting stem inter-nodes, roots, berries and leaves. The highest specific activity was found in the berries and was about 10 times higher than the one extracted from the leaves. Leaf wounding and salicylic acid treatment were able to rise the basal leaf activity by factors of 4.9 and 5.5, respectively. Up to 13 chitinase isoforms (4 basic and 9 acidic) could be identified in various untreated grapevine tissues by a combination of native IEF and PAGE. Untreated leaves were found to express six (four basic and two acidic) isoforms. Wounding of leaf tissue resulted in the appearance of four new acidic isoforms which have also been identified in berry extracts, one of them being present in the roots. Treatment of wounded leaves with 1 mM salicylic acid provoked a slight further increase of these four chitinases and greatly stimulated three of the basic constitutive isoforms. One of the latter was leaf specific while the two other ones were present in the stems, roots and berries.