The fatty acid composition of phosphatidylglycerol and sulfoquinovosyldiacylglycerol of Zea mays genotypes differing in chilling susceptibility

The content and fatty acid composition of four major chloroplast lipids, mo nogalactosyldiacylglycerol, digalactosyldiacylglycerol, phosphatidylglycero l and sulfoquinovosyldiacylglycerol, have been measured in the intact leave s of maize inbred lines differing in chilling susceptibility. Visual assess ment of chilling injury symptoms during post-chilling recovery of seedlings indicated that both lines CM 7 and Co 151 were more chilling susceptible t han lines S 215 and EP 1, exhibiting greater chilling tolerance. Fatty acid composition of chloroplast polar lipids was very similar and som e small deviation in the content of individual fatty acids did not affect u niformity of the general pattern. In all four lines of maize the content of height-temperature melting fraction of phosphatidylglycerol (htm-PG) and d ouble bond index of polar lipids were equal, while fatty acid composition o f polar lipids was very similar despite of small deviations in the content of individual fatty acid. Although the level of the high-temperature meltin g fraction of sulfoquinovosyldiacylglycerol (htm-SQDG) was lower in CS and CT lines Co 151 and S 215, respectively, than in CS and CT lines CM 7 and E P 1, respectively, this difference could not be related to their chilling s ensitivity. All of these data do not support the concepts that the level of htm-PG alon e or in combination with low-temperature-melting lipid would differentiate the chilling sensitivity of maize inbred lines. It is likely that some othe r factors are responsible for differential injury symptoms observed in chil led maize seedlings upon recovery. Discrepancies between the level of htm-P G and chilling sensitivity in several other species as well as various effe cts of acclimation on the level of htm-PG and temperature of phase transiti on are discussed.