Oleic Acid and Its Positional Isomer, cis-Vaccinic Acid, in the Appendix of Sauromatum guttatum during Anthesis

Abstract

California 9561 6 (E.R.S.); and Fairchild Tropical Garden, l h e fatty acid profiles of various organs of the thermogenic inflorescence of Sauromatum guttatum and of the sporophylls of thermogenic male cones of two cycad species (fncephalartos ferox and Dioon edule var edule and var angustifolium) were determined by gas chromatography. During anthesis, palmitate (1 6:0), oleate [18:1 (9)], cis-vaccinate [18:1 (ll)], and linoleate [18:2 (9, 12)l were the most abundant fatty acids i n the Sauromatum appendix.cis-Vaccinic acid, a positional isomer of oleic acid, was identified by comparing its retention time on a gas chromatography column and its mass spectrum to an authentic compound. The percentage of oleic acid from total fatty acids dropped from about 9 in the morning 3 d before heat production to 6 in the morning 2 d before heat production. At this time, the percentage of cis-vaccinic acid increased from 3 to 11 %, and then remained at this level until the inflorescence dried and died. Palmitoleic acid [16:1 (9)], the common precursor of cis-vaccinic acid, is a minor component of total fatty acids. In six other organs of the Sauromatum inflorescence including thermogenic organs, such as male flowers and lower spadix, palmitate, oleate, and linoleate were prevalent but cisvaccinate was not. The thermogenic male cones of the two cycad species were rich i n palmitic, oleic, and linolenic acids. The level of cis-vaccinic acid i n these organs was less than 0.5%.One striking example of a thermogenic plant organ is provided by the inflorescence of Sauromatum guttatum (the voodoo lily). On D-day, the day of inflorescence opening, the Sauromatum appendix (a 20-cm-long, slender organ) becomes hot, reaching a temperature of 32°C (Skubatz et al., 1991). The heat facilitates the vaporization of odoriferous compounds that attract pollinators; the heat loss reaches a value of 1 mW/mg dry weight . The heat is generated by the mitochondria via an alternative, cyanide-resistant pathway. The activity of this pathway, which is present in the mitochondria of many plant species, does not produce ATP, and the energy is thus released as heat (Siedow and Moore, 1993).Electron microscopic study of the Sauromatum appendix has revealed the presence of numerous lipid bodies in the cells ). It appears that the lipid bodies,

The Sauromatum guttatum appendix as an osmophore: excretory pathways, composition of volatiles and attractiveness to insects

“…These pockets accumulate terpenes that stay in these pockets until D-day, the day of heatproduction, when they are liberated to the atmosphere (Skubatz et al, 1995a). In the present paper we demonstrate that the interaction between the endoplasmic reticulum and the plasma membrane is very complex and that it seems to form additional new excretory pathways of volatiles.…”

“…Therefore, this structure might be involved in the breakdown of triglycerides stored in the lipid bodies (Murphy, 1990) to volatiles. We have shown that on D-day the amount of lipids decreases dramatically (Skubatz et al 19956) and this decrease might contribute to the release of lipidic volatiles. The presence of free fatty acids in the volatile mixture supports our conclusion that the conversion of fattj' acids to volatiles is carried out at the periphery of the cell, so that these volatiles can be discharged immediately upon production.…”

“…The inflorescences of Sauromatum guttatufn Schott. were allowed to develop under the conditions described previously (Skubatz, Kunkel & Meeuse, 1993). The developmental stage of the appendix has been determined retrospectively with respect to the day of inflorescence-opening and heat-production (D-day; Chen & Meeuse, 1971).…”

“…Tissue blocks were fixed in glutaraldehyde followed by osmium tetroxide as previously described (Skubatz et aL., 1993). Ultrathin sections (silver to light-yellow interference colour) from the subepidermal tissue (1-20) cell layers beneath the epidermis) were examined on a Philips-410 electron microscope.…”

“…One /il w^as injected into the the gas chromatograph column. The running conditions of the GC and the MS parameters have been previously described (Skubatz et aL, 1995a).…”