Carla Murelli

Surface waxes from olive fruits

Abstract The chloroform-soluble waxes of green and black olive fruits ( Olea europaea cv Coratina) contain alkanes (C 23 –C 33 ), saturated and unsaturated alkyl esters (C 38 –C 56 ), aldehydes (C 24 –C 30 ), methyl phenyl esters, triacylglycerols, alcohols (C 22 –C 28 ), fatty acids (C 16 –C 28 ), and pentacyclic triterpenols and triterpenoid acids. Oleanolic acid and triacylglycerols are the major components. Uvaol and erythrodiol, present in substantial amount in wax from green olives, were present only in trace amounts in that from black olives.

Low molecular weight solutes in desiccated and ABA-treated calli and leaves of Craterostigma plantagineum

Abstract Craterostigma plantagineum, a resurrection plant, displays extreme desiccation tolerance; dehydrated leaves and ABA-treated calli resume a normal metabolic state upon rehydration. Samples of calli and leaves of C. plantagineum were analysed for the major classes of compounds such as sugars, fatty acids, amino acids and derivatives, and phytosterols. Calli solutes are characterized by large amounts of glutamine and tyramine, triterpene acids and colneleic acid, an inhibitor of lipoxygenase. Among the sugars extracted from calli, sucrose, together with its hydrolytic products, predominates, while maslinic, ursolic and oleanolic acids are the most important triterpenes. In leaves the most common triterpene alcohols were campesterol, stigmasterol and β-sitosterol. Almost 50% of the weight of the lyophilized material consisted of 2-octulose, a sugar present as a minor component in a limited spectrum of plant species. Acquisition of desiccation tolerance in ABA-treated and desiccated calli was accompanied by an increase of fatty acids, accumulation of colneleic acid and by the disappearance of glucose and fructose. The most relevant biochemical effect of desiccation on leaves was the conversion of 2-octulose into sucrose.

Changes of low-molecular weight substances in boea hygroscopica in response to desiccation and rehydration

Abstract Boea hygroscopica is a poikilohydrous plant. This and similar species are also called desiccation-tolerant or resurrection plants. They have the unique ability to revive from an extreme air-dry condition. Samples of fresh, dried and rehydrated leaves were analysed for the major classes of organic substances like sugars, alditols, inositols, fatty acids, amino acids, betaines, phytosterols and others. The compounds which accumulated in desiccated leaves were sucrose and polyunsaturated C 18 acids. Abietanes and pimaranes were also detected. Monosaccharides, which are present in fresh leaves, disappeared, whilst phytosterols, stearic and oleic acids decreased to low levels; paimitic acid was unchanged. Rehydration of dried leaves seemed to restore the chemical composition of unstressed leaves. Betaines were not detected in any of the plant samples examined.

Epicuticular wax of olive leaves

Abstract The main components of the chloroform-soluble epicuticular waxes from olive tree leaves (Olea europaea cvs Coratina and Cipressino), were triterpene oleanolic and betulinic acids and triterpenols sitosterol, α- and β-amyrin, uvaol and erythrodiol. The waxes of both cultivars contain the ubiquitous wax classes of alkanes, alcohols, aldehydes, fatty acids and alkyl esters. Methyl phenyl esters and 2-phenyl-ethanol-1-esters were both present in low amounts in cv. Coratina whilst cv. Cipressino contained only the former class of compounds. Furthermore cv. Coratina contained triacylglycerols that were missing in cv. Cipressino wax.

Maize pollen lipids.

Abstract The chloroform extractives of four wild selections of Zea mays pollen were separated quantitatively into chemical classes and the components of each class were identified. Alkanes, alkenes, fatty acids, triterpene esters and triglycerides were found as the main constituents of the lipid extracts. The two hydrocarbon classes were found in a ratio close to 1:1; pentacosane, heptacosane and nonacosane were dominating in the alkanes, whilst alkenes showed major homologues two carbon atoms longer. Free fatty acids, 8–22% of the total, contained predominantly palmitic (16:0), stearic (18:0), oleic (18:1), linoleic (18:2) and lower amounts of palmitoleic (16:1) and linolenic (18:3) acids. Triglycerides and triterpene esters accounted for 17–31 % and 5–34%, respectively. The former class comprised three homologous series, the latter contained tetracyclic and pentacyclic triterpenes esterified with C16 and C18 fatty acids. Free triterpenols and linear esters were also found in pollen lipids. These data are discussed in relation to pollen biochemistry and in regard to the natural functions of the lipid classes found.

Low-molecular weight substances from the resurrection plant Sporobolus stapfianus

Abstract Sporobolus stapfianus Gandoger is a typical desiccation-tolerant or resurrection plant, which survives almost total dehydration. Samples of fresh,

Aliphatic and cyclic lipid components of Sorghum plant organs.

Abstract Wax components of the aerial parts of mature plants of Sorghum bicolor were compared with those from the panicles and mature grains. Lipid content of the grain flour was also analysed. Attention has been paid to the polycyclic triterpenes distributions comparing different varieties of sorghum. The general occurrence of hopanoids suggests that they are significant chemotaxonomic markers for S. bicolor. Dotriacantanol was found to characterize the lipid content of the grain flour. Observations on this finding are reported.

Composition and structure of maize epicuticular wax esters

Abstract The structural composition is reported of epicuticular wax esters from maize. The waxes from wild type ( Gl ) plants at different stages of growth and those from some glossy ( gl ) seedlings and an albino strain of maize have been analysed for their content of esters. Influence of age and mutations on the epicuticular wax ester composition is discussed.

The influence of growing season on fruit yield and quality of greenhouse melon (Cucumis melo L.) grown in nutrient film technique in a Mediterranean climate

Summary The influence of growing season on some physiological and biochemical variates related to fruit yield and quality was investigated in melon (Cucumis melo L.) plants cultivated in nutrient film technique in a greenhouse located at Pisa, Central Italy, from mid-March to mid-June, or from mid-July to mid-September. Compared with spring, the plants grown in summer exhibited faster growth and development, but produced fewer fruits of larger size and poorer quality due to reduced sucrose content. Growing season did not affect total leaf area, but dry-matter production and partitioning to the fruits was significantly lower in summer than in spring. Summer fruit ripened within 30–35 d after anthesis, about 14 d fewer than in spring. Higher average temperature was presumably responsible for earlier fruit maturation in summer, as in both seasons all melons were harvested after 450–500 degree-days (base temperature of 12°C) from anthesis. Fruit swelling did not account for the reduction of sucrose content in summer-grown fruits, which instead was due to shortage of photoassimilate supply and inadequate sucrose synthesis, as suggested by the rate of leaf gas exchange and the activity of sucrose phosphate synthase in the fruit flesh, as determined during the final stages of fruit development. Lower solar radiation was presumably responsible for the reduced leaf carbon assimilation in summer, as growing season did not affect leaf turgor, stomatal conductance, mineral status and chlorophyll content.

Galactinol in the leaves of the resurrection plant Boea hygroscopica

Abstract The content of low molecular weight substances was analysed in leaf samples of the resurrection plant Boea hygroscopica F. Muell. submitted to dehydration. Drying treatment caused a variation in the carbohydrate pool, with a decrease of all sugars except sucrose which notably increased, becoming the prevalent one in dried leaves. Rehydration almost restored the pre-treatment sugar composition. Along with more common sugars galactinol and some higher oligosaccharides of the raffinose family were detected. Their structures were assigned by NMR and GC–MS analyses after acetylation. To our knowledge, this is the first finding in resurrection plants of significant amounts of the galactosyl donor galactinol and of higher galactosyl oligosaccharides, which may have a role in restoring the pre-drying functions upon rehydration.