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

Giardini Naxos, Italy - 18/21 September, 2002

ISBN 88-900622-3-1

Poster Abstract - 2.10

EXPRESSION PATTERN OF A TRANSGENE IN TOMATO PLANTS: THE CASE OF AN HAMMERHEAD RIBOZYME TARGETED TO ENDO-b-GLUCANASES

Salfi l., marino i., stigliani a.l., d’ambrosio c., cellini f.

Metapontum Agrobios SS Jonica, Km 448.2, Metaponto (MT)

cdambrosio@agrobios.it

EGase, tomato, hammerhead ribozyme, transgenic plants

Textural properties of processing tomatoes are crucial to ensuring product acceptability. Viscosity and consistency of tomato paste are two of the most important characteristics among the quality attributes of processed tomato products and they are strictly related to changes in the structure of fruit primary cell wall. The endo-1,4-b glucanases (EGases) are one of the enzymatic group involved in the modification of the primary cell wall. In tomato, Egases are encoded by a gene family consisting of at least eight members and present some redundancy of function. For this reason the down-regulation of a single EGase did not allow any modification of the textural properties. Thus we explored the possibility to simultaneously down-regulate the expression of several EGases using the ribozyme strategy. Specifically we constructed a hammerhead ribozyme (Ribo358) in order to suppress mRNA accumulation of tcel3, tcel5, tcel8 at the same time.

T1 tomato fruits coming from transgenic plants carrying the Ribo358 under the control of 35S promoter were analysed in order to determine the textural parameters. The measurement of viscosity allowed the identification of 6 plants derived from 4 T0 transgenic genotypes, which had a very high pulp viscosity value. Transgenic progeny of two high viscosity lines were examined for the expression of ribozyme transgene in leaves and in fruits at different developmental stages. The results show that in T2 generation the transgene is stably inherited and expressed. Intriguingly, although Ribo358 is under the control of a constitutive promoter, the expression levels vary among different organs but they result independent of the developmental stage. Further investigations are in progress to shed light on this aspect.

Acknowledgments: This work was partially supported by the Italian Ministry of the University and, Scientific and Technological Research within the Project 4: “Innovazione tecnologica nel sistema agro-industriale: uso delle biotecnologie per lo sviluppo di nuovi prodotti.”.