Abstract
In Lycopersicon esculentum Mill, the phosphoglucoisomerase (pgi) zymogram changes during seed germination. Dry seeds display bands A-D in similar intensities whereas seeds imbibed 24 h show almost exclusively the A and D bands. Evidence presented here supports the hypothesis that a single gene Pgi-1 codes for bands B-D, demonstrating that changes in isozymic banding patterns do not necessarily reflect a change in structural gene expression.