Lack of Influence of the Epidermis on Underlying Cell Development in Leaflets ofPisum sativumvar.argenteum(Fabaceae)

We explored whether epidermal pressure regulates cell and organgrowth in leaflets ofPisum sativumvar.argenteum,a mutant cultivarof the garden pea characterized by reduced adhesion betweenthe epidermis and subjacent mesophyll. Developing leaflets ofleaves arising at three positions on the seedling axis werepeeledin situand grown to maturity in humidity chambers. Themature anatomy and morphology could be accurately assessed becausewound responses normally associated with peeling were preventedby theArgmutation that permitted peeling without damage to themesophyll and by the humidity chambers that protected peeledareas from desiccation. The mesophyll cell size, state of differentiation,and layering pattern as well as the overall morphology of mature,peeled leaflets were indistinguishable from those of mature,intact leaflets grown under the same conditions. The epidermisexerted no detectable regulatory effect on the expansion ofthe leaflets as a whole or on the tissue layers and cells withinthe leaflets.Copyright 1999 Annals of Botany Company. Biomechanics, compression, epidermis, leaf development, mesophyll, pressure, wound response,Pisum sativumvar.argenteum.