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

Salsomaggiore Terme, Italy - 26/29 September, 2001

ISBN 88-900622-1-5

Poster Abstract

OVEREXPRESSION OF A MODIFIED PROSYSTEMIN GENE IN TOBACCO PLANTS REDUCES THE DEVELOPMENT OF LEPIDOPTERAN LARVAE

TORTIGLIONE C.*, FANTI P.**, PENNACCHIO F.**, RAO R.***

* Istituto Miglioramento Genetico delle Piante da Orto e da Fiore, CNR, Portici, Italia

** Dipartimento di Biologia e Difesa Agroforestale, Università della Basilicata, Potenza, Italia

*** Dipartimento di Scienze Agronomiche e Genetica Vegetale, Università di Napoli, Portici, Italia

Plants can be protected from insects by expressing insecticidal protein either from plant or bacterial origin. We describe here an alternative approach for generating insect tolerant tobacco varieties. We introduced into Nicotiana tabacum the prosystemin gene engeneered in such a way to release an insect hormon (TMOF) instead of the systemin , a 18 aminoacid polypeptide inducer of more than 20 systeminc wound inducible genes (swips) in tomato plants. Systemin is synthesised as a part of a longer precursor, prosystemin, which is a 200 amino acid protein with a molecular mass of and it is endoproteolytically processed from the precursor. However, the putative bordering processing sites are undetermined, and do not conform to the consesus sequence for endoproteolytic processing sites flanking bioactive peptides in animal prohormone precursors. In order to express in plant the 10 aminoacid TMOF peptide, we engineered the prosystemin gene substituing the systemin DNA sequence with the TMOF DNA sequence, keeping unaltered the putative bordering processing sites. Another construct was produced simply deleting the systemin DNA sequence, with the aim to test putative toxicity caused by the truncated prosystemin gene itself. In fact, up to now, no data aare available on the possible function of the prosystemin precursor, althought there are evidences for proteinase inducing activity in the systemin encoding domain. Both the prosystemin-TMOF fusion and the prosystemin truncated genes, driven by the 35S2 CaMV promoter, were cloned into the binary vector PKLY71:S2 and used to stably transform tobacco plants by standard Agrobacterium tumefaciens mediated protocols. Many independently transformed plants selected for the presence of the foreign gene by PCR were propagated in vitro and in vivo. The molecular analysis of transgenic plants and the preliminary in vivo assays of their toxicity against lepidoptera insects is here reported and for the first time the functional role of the truncated prosystemin gene is discussed.