The Impact of Mutations in the HvCPD and HvBRI1 Genes on the Physicochemical Properties of the Membranes from Barley Acclimated to Low/High Temperatures

Abstract

(1) Background: The study characterized barley mutants with brassinosteroid (BR) biosynthesis and signaling disturbances in terms of the physicochemical/structural properties of membranes to enrich the knowledge about the role of brassinosteroids for lipid metabolism and membrane functioning. (2) Methods: The Langmuir method was used to investigate the properties of the physicochemical membranes. Langmuir monolayers were formed from the lipid fractions isolated from the plants growing at 20 °C and then acclimated at 5 °C or 27 °C. The fatty acid composition of the lipids was estimated using gas chromatography. (3) Results: The BR-biosynthesis and BR-signaling mutants of barley were characterized by a temperature-dependent altered molar percentage of fatty acids (from 14:0 to 20:1) in their galactolipid and phospholipid fractions in comparison to wild-type (WT). For example, the mutants had a lower molar percentage of 18:3 in the phospholipid (PL) fraction. The same regularity was observed at 5 °C. It resulted in altered physicochemical parameters of the membranes (Alim, πcoll, Cs−1). (4) Conclusions: BR may be involved in regulating fatty acid biosynthesis or their transport/incorporation into the cell membranes. Mutants had altered physicochemical parameters of their membranes, compared to the WT, which suggests that BR may have a multidirectional impact on the membrane-dependent physiological processes.

Molecular Dynamics of Chloroplast Membranes Isolated from Wild-Type Barley and a Brassinosteroid-Deficient Mutant Acclimated to Low and High Temperatures

“…According to Hölzl and Dörmann [ 37 ], chloroplasts are the major sites for FA synthesis in plant cells and 16:0, 18:1 Δ9cis , 18:2 Δ9cis,12cis and 18:3 Δ9cis,12cis,15cis FA are present at the highest levels in the chloroplast membranes. Therefore, our data are generally consistent with this [ 37 ] and other previous works on chloroplasts that had been isolated from avocado fruits and cauliflower leaves [ 38 ], as well as on the callus of winter oilseed rape [ 39 ] and on the leaves of Pisum sativum L, winter wheat, and barley [ 13 , 40 , 41 ].…”

“…In case of monolayers built from DGDG values of A lim were 55.2 ± 0.1 and 51.7 ± 0.2, respectively for Delisa and mutant. Usually, greater fluidity of cell membranes is considered as more favourable for a higher frost tolerance, which has been wider discussed in our earlier work [ 13 ]. The 522DK mutant, which has a slightly higher frost tolerance than the wild type Delisa [ 20 ], is, however, characterized by a greater rigidity of chloroplast membranes than Delisa, as shown in EPR studies.…”

“…Recently, we found that BR may be involved in regulating the accumulation of the proteins that are incorporated in the cell membranes of barley plants (heat shock proteins, proton pumps and aquaporins) [ 11 , 12 ]. Our most recent studies revealed that barley mutants with a BR deficiency or a BR insensitivity were characterised by a different fatty acid composition in the cell membranes, which resulted in altered membrane physicochemical properties that could have an impact on the membrane-dependent physiological processes [ 13 ].…”

Brassinosteroids and the Tolerance of Cereals to Low and High Temperature Stress: Photosynthesis and the Physicochemical Properties of Cell Membranes

“…Barley with defects in BR-biosynthesis and BR-signaling is characterized by a temperature-dependent altered molar percentage of fatty acids (from 14:0 to 20:1) in their phospholipid and galactolipid fractions compared to the reference cultivar [ 36 ]. Specifically, the mutants had a lower molar percentage of 18:3 FA in their phospholipid fraction and this regularity was maintained at 5 °C while the reverse effect was observed at 27 °C.…”

“…In some cases, this state of knowledge may require some verification and/or confirmation, for example, in research using mutants. This review focuses mainly on the achievements in the study of the acclimation processes to frost and high temperature in barley ( Hordeum vulgare L.) and its mutants with an impaired BR biosynthesis (a reduced content of BR from the C 28 and C 29 groups) and an impaired perception of BR (a defect of the BRI1 receptor and an increased content of BR from the C 28 group) [ 13 , 34 , 35 , 36 , 37 ] in recent years. The knowledge that was gained in these studies is discussed against the background of the results of other/previous works on cereals, especially those that included experiments where BR were applied exogenously.…”