Is phenol oxidation responsible for the short-term effects of boron deficiency on plasma-membrane permeability and function in squash roots?

The aim of the present work was to study the effects of boron (B) deficiency on membrane integrity and function in the roots of squash plants, as well as to ascertain the role of oxidation of phenolics in these processes in this organ. In this experiment, we analysed the leakage of the phenolics, amino acids, sucrose, and K+, and the activities of ATPase (EC 3.6.1.35), Fe(III)-chelate reductase (FC-R, EC 1.6.99.13), polyphenol oxidase (EC 1.14.18.1), and peroxidase (EC 1.11.1.7). Here, we suggest that the B deficiency first rapidly alters ion and solute flows, this being associated with permeability loss, while the decline in functionality (ATPase and FC-R activities) appears when B deficiency becomes more severe. Finally, our results exclude the involvement of phenol oxidation in the loss of plasma-membrane integrity and functionality in the roots of squash plants.