Phospholipid Acyl Chain and Phospholipase Dynamics during Cold Acclimation of Winter Wheat (original) (raw)

on the phospholipid profiles. It has been suggested that alterations in concentration of specific phospholipids Phospholipid (PL) composition is known to change in plants explay a role in cold acclimation. Horvath et al. (1979) posed to cold temperature. The dynamics of PL acyl chain pairs and genes encoding phospholipase enzymes were studied in winter wheat observed an inverse relationship between survival and (Triticum aestivum L.) during cold acclimation. Mass spectrometry the loss of phosphatidylcholine by conversion to the corwas used to characterize PL dynamics, and quantitative real-time responding phosphatidic acid in field-grown wheat PCR was used to characterize phospholipase gene mRNA transcript plants. A similar conversion of phosphatidylcholine to dynamics during cold acclimation. The proportion of PLs with misphosphatidic acid was reported by De La Roche and matched acyl chains decreased concomitantly with an increase in total Andrews (1973) in plants grown at 2ЊC and morphologi-PLs during the first week of cold exposure. Proportions of mismatched cally equivalent plants grown at 24ЊC, again suggesting acyl chains then increased, while total PLs varied little. Numbers of these phospholipid dynamics are a function of plant phe-mRNA transcripts of phospholipase (PL)D, PLC, and PLA 2 increased nology rather than cold acclimation. in response to cold and remained at elevated levels throughout a 4-wk The proportion of unsaturated fatty acids, particularly period. Lysophosphatidylcholine (LPC) increased as much as 14-fold over the 5-wk period and increased significantly less in a less cold linolenic acid (18 carbons, three double bonds [18:3]), tolerant cultivar than more tolerant cultivars. It appeared that newly increased during cold acclimation at the expense of less synthesized PLs with equal-length acyl chains form a part of the initial saturated forms (De La Roche et al., 1972, 1975; Skocresponse to cold temperature; they are then modified to contain nearzowski et al., 1994; Sopin and Trunova, 1991; Willemot initial levels of mismatched acyl chains during acclimation. LPC is a and Pelletier, 1980; Willemot et al., 1977a, 1977b). Howhighly active signal molecule and PLA 2 , PLC, and PLD are involved ever, it has been demonstrated that the accumulation in generation of phospholipid-based signaling molecules; hence, it of linolenic acid per se is not required for the developappeared PL signaling is involved in initial and continuing responses ment of freezing tolerance (De La Roche, 1979). Szalai to cold temperature.