Proceedings of the XLVII Italian Society of Agricultural Genetics - SIGA Annual Congress

Verona, Italy - 24/27 September, 2003

ISBN 88-900622-4-X

Poster Abstract - 4.02

The knotted-like class 1 KNAPE1 of peach is triggered and ectopically expressed in leaf affected by the curl disease caused by Taphrina deformans

L. Bruno*, D. Giannino**, A. Chiappetta*, R. Cozza*, A. Tartarini**, D. Mariotti**, A.M. Innocenti*, M.B. Bitonti*

*) Università della Calabria, Dipartimento di Ecologia - Laboratorio di Botanica, Cubo 6B, Arcavacata di Rende, I-87030 Cosenza, Italy

**) Istituto di Biologia e Biotecnologia Agraria (sez. di Roma), Via Salaria km 29.300, 00016 Monterotondo Scalo (RM)

peach, leaf curl disease, knotted-like genes class 1, cytokinins

In plants, the homeobox containing knotted-like genes (KNOX) class 1 are required for meristem function and determine leaf identity upon down regulation. Most of KNOX class 1 genes are expressed in the shoot apical meristem and excluded from leaf primordia. Mutations of these genes result in a failure to initiate or maintain a SAM, whereas their ectopic expression alters normal leaf morphology, involving a misbalance of hormone metabolism. A knotted-like gene was previously isolated and characterised in peach (KNAPE1) and attributed to class1 on the basis of sequence homology and meristem specific expression pattern. The triggering of KNAPE1 expression was observed in leaves affected by the curl disease, caused by Taphrina deformans, a pathogenic fungus which produces auxin and cytokinin-like compounds. Message localisation was monitored during distinct stages of disease and the ectopic expression was observed in curly sectors, corresponding to areas of histological disorder. This pattern is associated with an indeterminate cell identity, leading to a non coordinate cell proliferation, which may involve a misbalance and/or misallocation of cytokinins. Consequently, immunolocalisation of zeatine was performed and zonation patterns suggest a spatial and temporal relation with the reactivation of KNAPE1.