The Plant Cell, Vol. 4, 667-679, June 1992 O 1992 American Society of Plant Physiologists

An Antisense Pectin Methylesterase Gene Alters Pectin Chemistry and Soluble Solids in Tomato Fruit Denise M. Tieman, Robert W. Harriman,' G. Ramamohan, and Avtar K. Handa' Department of Horticulture, Purdue University, 1165 Horticulture Building, West Lafayette, Indiana 47907-1165

Pectin methylesterase (PME, EC 3.1.11) demethoxylates pectins and is believed to be involved in degradation of pectic cell wall components by polygalacturonasein ripening tomato fruit. We have introduced antisense and sense chimeric PME genes into tomato to elucidate the role of PME in fruit development and ripening. Fruits from transgenic plants expressing high levels of antisense PME RNA showed