Rapid Effects of Boron Deficiency on Cell Wall Elasticity Modulus in Cucurbita pepo Roots

Rinsing roots of Cucurbita pepo with an essentially boron‐free nutrient solution results in a significant reduction of the cell wall elasticity modulus as determined by the cell presure probe (measuring always in the same cells). This points to a role of boron in crosslinking cell wall macromolecules. Longer exposure to boron deficient conditions, however, increased again and above the initial values. This trend became visible between 20 and 30 minutes after starting the deficiency treatment. There is no indication for a loss of turgor during the time course of the experiments, suggesting that boron primarily affects cell wall physical properties and that membrane leakiness, as observed by other groups, is a secondary event. Several testable hypotheses for the action of boron are presented.