Antisense suppression of a potato alpha-SNAP homologue leads to alterations in cellular development and assimilate distribution

Using the cDNA-AFLP method, we have isolated a transcript-derived fragment (TDF) which shows a differential expression pattern during tuber organogene sis of Solanum tuberosum L. The TDF was used to isolate a cDNA clone carryi ng a 1.5 kb insert and potentially coding for a 32.5 kDa peptide which, by homology, represents a potato homologue of an alpha-snap gene and has been designated Stsnap. Northern analysis showed that the Stsnap gene is express ed in actively dividing tissues throughout the potato plant. Analysis of ge nomic DNA from potato revealed that the Stsnap gene is likely to be a singl e-copy gene. The expression of antisense Stsnap cDNA under the control of t he CaMV 35S promoter results in plants with an altered morphology such as c urled leaves. Several of these transgenic lines also display cellular and d evelopmental abnormalities with distinct changes in assimilate transport in cluding accumulation of starch and soluble sugars in source leaves. We argu e that these findings are consistent with the hypothetical function of the StSNAP gene product in vesicle targeting and fusion during plant developmen t.