Changes in Membrane Polar Lipid Fatty Acids of Seashore Paspalum in Response to Low Temperature Exposure

Abstract

ters, however, these organs can be killed when the frost zone moves below the rhizome layer. Even during rela-Seashore paspalum (Paspalum vaginatum Sw.) is a warm-season tively mild winters, the crowns and rhizomes are suscepturfgrass, best known for its superior salt tolerance. Plants are subject tible to injury due to the cold. Reestablishment of damto injury during winter conditions along the northern boundary of aged turf is expensive both in terms of labor and plant their zone of adaptation. New cultivars that are more tolerant to low temperatures are needed for use in the transition zone. Cold material. Thus, a more complete understanding of the tolerance has been correlated with the degree of unsaturation in tolerance of warm season grasses to low temperatures membrane lipid fatty acids. Unsaturated fatty acids are thought to is needed to improve their utility and extend their range. aid in maintaining membranes in a fluid state necessary for biological Whereas most temperate perennial plants can survive functioning (homeophasic adaptation). The primary objective was extensive exposure to subfreezing conditions, most tropto characterize fatty acid composition of membrane lipids in three ical and a number of subtropical plants have little or no genotypes differing in cold tolerance. A second objective was to invescapacity to withstand freezing temperatures. A plant's tigate changes in fatty acid content in these genotypes during exposure ability to alter its physiology in response to low temperato low temperatures. Cold-treated plants were exposed to a 10-h ture, such that it can survive otherwise lethal temperaphotoperiod at 8؇/4؇C day/night temperatures and light intensity of tures, is called cold acclimation (hardening). The pro-250 mol m Ϫ2 s Ϫ1 photosynthetic photon flux density for 3 wk. Rhizomes and crowns were harvested at 7-d intervals. Total lipids were cess of cold acclimation occurs seasonally when plants extracted and the polar lipids separated by thin-layer chromatography. are exposed to low, nonfreezing temperatures beforeFatty acids were identified by gas chromatography (GC) and mass the onset of winter (Levitt, 1980). Some C4 grasses have spectroscopy. In all three genotypes, the two saturated fatty acids, been shown to cold acclimate (Anderson et al., 1988, palmitic acid and stearic acid, did not change during cold treatment. 1993). The biochemical changes accompanying acclima-The triunsaturated linolenic acid increased significantly during low tion to low temperature include alterations in soluble temperature exposure. The magnitude of change was greater in the carbohydrate content, synthesis, and conformation of finer-textured and more cold-tolerant PI 509018-1 ('SeaIsle1') than in proteins and changes in membrane lipid composition the intermediately cold-tolerant 'Adalayd' or in the cold-susceptible, and fatty acid saturation (Li, 1984; Sakai and Larcher, coarse-textured PI 299042. These findings suggest that accumulation 1987; Hallgren and Oquist, 1990). Many of the new of linolenic ac...

Estimation of Rhizome Composition and Overwintering Ability in Perennial Sorghum spp. Using Near-Infrared Spectroscopy (NIRS)

“…One of the most notable differences between our data and that from previous studies is that we observed a negative correlation between fat content and overwintering ability. This finding is in contrast to observations on Arabidopsis above-ground growth [37] and what was hypothesized for the genus Paspalum based in part on studying rhizomes cut from plants and buried in the ground [38,39]. Although our finding was unexpected, it is supported by significant correlations during both sampling dates for the College Station soil column studies.…”

“…In fact, if higher fat content allows a plant to continue to metabolize at lower temperatures, it may also cause the plant to use its stored energy during the winter months and deplete the plant of resources for regrowth the following year, therefore decreasing the rhizomes' ability to successfully overwinter. Another possible explanation for our findings is that the ratio of different fatty acids may be more influential to cold tolerance than the total fat content [38,40]. Similar to fat, starch concentrations were negatively correlated with overwintering.…”

Depletion of the Membrane-Associated Acyl-Coenzyme A-Binding Protein ACBP1 Enhances the Ability of Cold Acclimation in Arabidopsis

“…This is accompanied by changes in lipid composition that modulate membrane stabilization (Thomashow, 1999). Increases in the proportion of PL in the plasma membrane during cold acclimation are commonly observed in various herbaceous and woody species, such as rye (Uemura and Steponkus, 1994), oat (Avena sativa; Uemura and Steponkus, 1994), seashore paspalum (Paspalum vaginatum; Cyril et al, 2002), Arabidopsis (Uemura et al, 1995;Welti et al, 2002), and mulberry (Morus bombycis; Yoshida, 1984). Under low-temperature stress, an increase in the ratio of unsaturated PL is a crucial factor in maintaining the biological functions of membranes (Nishida and Murata, 1996).…”

Quantitative trait loci of frost tolerance and physiologically related trait in faba bean (Vicia faba L.)

“…Responses of plants to hardening were observed on oligogenic traits such as (1) accumulation of sucrose and other simple sugars (Pollock 1986;Santoiani et al 1993), (2) increase of total protein concentration (Davis and Gilbert 1970;McKenzie et al 1988), (3) accumulation of free proline (Petcu and Terbea 1995;Dörffling et al 1997;Thomashow 1999), (4) increase of the cell membranes stability (Chandrasekar et al 2000), (5) increase of total lipids and their polyunsaturated fatty acid content (linoleic and linolenic acids), and (6) increase of desaturase enzyme activity (Cyril et al 2002;Wei et al 2005). Recent studies in faba bean showed that polyunsaturated fatty acid accumulation were adaptation mechanisms to low non-freezing temperatures, but also significant correlated traits to frost tolerance (Arbaoui et al 2008).…”