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 - 1.52

EXPRESSION ANALYSIS OF G1-1, A GENE ISOLATED IN POTATO TUBER DURING TRANSITION FROM DORMANCY TO SPROUTING

R. BIANCHI, C. AGRIMONTI, G. VISIOLI, N. MARMIROLI

Dipartimento di Scienze Ambientali, Università di Parma

sink-source transition, dormancy, sprouting, Real-Time RT- PCR

In potato tubers the transition from sink to source function is interrupted by a period of dormancy in which sprouts growth is completely inhibited. To investigate some of the molecular events of this process, an analysis by means of the differential display technique was previously undertaken, identifying the cDNA sequence G1-1, whose expression is induced in potato tubers at the end of the dormancy period and in the early phases of tuber sprouting.

The short ORF of G1-1 (226bp) shares 81 and 75% of nucleotide identity with two ESTs of tomato and soya respectively, isolated in different tissues having in common an intense mitotic activity. Northern analysis using mRNA from whole potato tubers had shown very low levels of expression, with a small increase in transition from the dormancy to the sprouting phase. In the present study, we have examined G1-1 expression at a more thorough level, in the tissues of tuber eyes, parenchyma, whole tuber, sprouts and leaves in different physiological stages, using the highly sensitive quantitative real time RT-PCR technique (TaqMan method).

The highest expression levels were found in actively growing tissues, such as sprouts and leaves collected during the first stage of their development, when they are still in the sink phase. The expression of G1-1 decreases, even though it remains quite high, in mature leaves, after their transition in the source phase. G1-1 is weakly expressed in parenchyma and whole tuber tissues, but an increasing expression has been observed in tuber eyes during the breakage of dormancy.

Thus, these results may suggest a connection between the expression of G1-1 and actively dividing tissues of sink organs.