Comparative analysis of the composition of sterols in embryogenic and nonembryogenic cell lines of <i>Larix sibirica</i> Ledeb.

Abstract

The cell lines of Siberian larch (Larix sibirica Ledeb.), possessing different embryogenic potential, were studied. Qualitative and quantitative content of sterol components was comparatively analyzed in their tissues with the help of gas chromatography-mass spectrometry. Significant differences in these parameters were found between both groups of the lines in fractions of free sterols and their esters. In addition to sterol compounds, squalen, which is a triterpenic intermediate in sterol biosynthesis, was revealed. Of free sterols, -sitosterol, campesterol, isofucosterol, and stigmasterol dominated in the embryogenic lines, while -sitosterol, campesterol, and stigmasterol in nonembryogenic ones. The campesterol concentration was 1.31.9 times higher in the embryogenic than nonembryogenic lines. Since campesterol is a precursor of brassinosteroids, it is likely that its level is high due to an embryogenic state of these cell lines. Only the embryogenic lines contained appreciable amounts of isofucosterol. The fraction of sterol esters exhibited wider component diversity in the nonembryogenic than the embryogenic lines. In all the cell lines, among the identified sterol esters, the substances without double bonds, bearing, as a structural fragment, a sterane coreperhydrocyclopenta[a]phenanthrenewere the most abundant. Their content ranged from 52 to 71% of the total amount of sterol esters. The revealed differences in the compositions of sterols and their esters, between the L. sibirica cell lines with different embryogenic potential, witness to the considerable rearrangements in sterol metabolism in the course of embryogenesis. The line-specific differences may indicate the involvement of these metabolites in formation of embryos.