Combined electron-spin-resonance, X-ray-diffraction studies on phospholipid vesicles obtained from cold-hardened wheats

Abstract

Phospholipid multibilayers, obtained from two cultivars of thermally acclimated wheats of different frost resistances (Triticum aestivum L. cv. Penjamo 62, the sensitive cultivar, and T. aestivum L. cv. Miranovskaja 808, the frost-resistant cultivar), were investigated using electron-spin-resonance and X-ray-diffraction techniques. The former technique revealed two breaks in the motion of the spin-labelled fatty acid 2-(14-carboxyte-tradecyl)-2-ethyl-4,4-dimethyl-3-oxazolidinyloxyl, for both cultivars (+3°C,-17° C and +5° C,-18° C, respectively) when grown at 22° C. The resistant cultivar compensated for exposure to cold (+2° C) by shifting the onset of the apparent phase-separation temperature from +3° C to-16° C. The sensitive cultivar was unable to do so. X-ray diffraction did not reveal fluid-to-gel transitions between +20° C and-10° C in any of the samples. The possible role of the formation of relatively ordered aggregates or clusters of lipid molecules discerned by spin probe within the otherwise freely dispersed liquid-like lipids is discussed in terms of freezing injury of plants.

The fatty acid constitution and ordering state of membranes in dominant temperature-sensitive lethal mutation and wild-typeDrosophila melanogaster larvae

“…This may be inferred from results obtained on microbial systems (Sinenski, 1974;Martin et al, 1981;Janoff et al, 1979;Dickens and Thompson, 1981), plants (Chapman et al, 1979;Furtado et al, 1979;Vigh et al, 1979Vigh et al, , 1986, Tetrahymena (Umeki et al, 1983), and some poikilothermic animals (Kallapur et al, 1982;Cossins, 1977;Farkas, 1984). Thus we may speculate that the seasonal occurrence or geographical distribution of different species is related to their ability to manipulate cell membranes in order to survive at a given temperature .…”

High and low pre‐inoculation temperatures decrease the effectiveness of the Lr 20 and Sr 15 rust resistance genes in wheat

“…Studies of the adaptation of thylakoid membranes of rye and wheat to low temperatures have suggested that, in varieties which differ in cold hardiness, membrane fluidity differs at the end of the hardening process (Vigh et al, 1979(Vigh et al, , 1987. We tested several sources of Sri5 back-crossed into either a spring wheat (Chinese Spring, Federation) or a winter wheat (Chancellor) background in order to investigate whether possible plasma membranerelated differences between cold-acclimatized spring and winter wheat backgrounds could affect the subsequent expression of SrJ5.…”