A Freeze-Fracture Study of the Cell Membranes of Wheat Adapted to Extracellular Freezing and to Growth at Low Temperatures

Publisher Website
Google Scholar
Abstract
Seedlings of Triticum aestivum L. cv. Lennox were grown in natural (late autumn) or controlled environments differing in temperature, to give plants differing either only in growth adaptation or also in hardiness. The frost hardiness of laminae and leaf bases was measured using an ion leakage method. Pieces of laminae and leaf bases were freeze-fixed without chemical cryo-protectant or chemical fixative. The number of particles per unit area of the E fracture face of the plasma membrane was substantially reduced in laminae from the environment inducing most hardening, compared to unhardened controls. This difference in frequency of particles on the E face was not related to adaptation of growth to low temperature (in the leaf bases) and was not an artificial consequence of chemical treatment prior to freeze-fixation. The density of particles on the P face of the plasma membrane was unaffected by growth environment. More limited data suggested the density of particles on either fracture face of the thylakoids was also unaffected. Unlike an earlier report, particle-free areas of plasma membrane were not found in hardened tissue. Environment did not affect (a) the width of the ‘mouth’ at the plasma membrane-plasmodesma junction in the leaf bases or (b) the size of the nuclear pores. Membrane accumulated below the plasma membrane only in some cells from the hardiest material.

This publication has 0 references indexed in Scilit: