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The columnar cacti Cereus peruvianus and C. jamacaru are being evaluated as potential new exotic fruit crops suitable for cultivation in arid zones. Sensory tests of fruits of two accessions of C. peruvianus (G2 and Q9) and two accessions of C. jamacaru (B3 and B6) indicated that the fruits of the two C. peruvianus cultivars are more palatable than those of the C. jamacaru clones. The study showed that analyses of volatiles and polysaccharides were good indicators of fruit quality (aroma and texture, respectively). However, sensory evaluations were found to be better indicators of quality than physico-chemical criteria that are conventionally in use for quality determination, such as titratable acidity, pH, sugars, and total soluble solids. The results obtained showed that sensory evaluations are of essential value as research tools capable of delineating sensory and quality profiles of fresh Cereus fruits.
Khat (Catha edulis Forsk., Celastraceae) is a perennial shrub that was introduced to Israel by Yemenite immigrants. Its young leaves are chewed for their psycho-stimulating properties. Young khat leaves contain the phenylpropylamino alkaloids (-)-cathinone [(S)-α-aminopropiophenone], (+)-cathine [(1S)(2S)-norpseudoephedrine], and (-)-norephedrine [(1R)(2S)-norephedrine] as the main active principles. A novel GC-MS analysis method for the quantitative determination of phenylpropylamino alkaloids and their putative biosynthetic precursor 1-phenylpropane-1,2- dione in khat leaves was developed. We utilized an alkaline-organic extraction, coupled with gas chromatography and a chiral permethylated beta cyclodextrin phase, to allow a full separation between the two diastereoisomers (1S)(2S)-cathine and (1R)(2 S)-norephedrine. We found a marked diversity in the phenylpropylamino alkaloid content and composition in three different locally grown accessions and the commercial cultivar ‘Mahanaim’.
Bitter fennel (Foeniculum vulgare Mill. var. vulgare, Apiaceae) is a hemicryptophyte native to the Mediterranean basin and cultivated for its use as a medicinal and spice. We describe here the flowering dynamics and crossability among six native populations of bitter fennel collected from four localities in Israel, one from Sinai Desert (Egypt), and one from Mersin (Turkey) and grown from under agricultural conditions. Timing and duration of the stigma's receptivity were evaluated morphologically, enzymatically, and by determining fruit set in response to artificial pollination. Self-compatibility rates and crossability within and between populations were also determined in response to artificial pollination. Although the populations initiated flowering at different times through the season, in all cases the stigma's receptivity peaked between six and eight days after anthesis (yellow-bud stage) and lasted for seven days. Pollen can primarily germinate on the stigmata but the stylopodium serves too as a site for pollen germination, albeit at a lower efficiency (0-10% fruit set) as compared to stigmata (25-54%). Although there is complete dichogamy within flowers, umbels, and branches, there in not enough dichogamy between branches, and geitonogamy is therefore possible. Additionally, all populations displayed a high (0.7-3.7) index of self-compatibility (ISI), indicative of substantial self-pollination. Although interbreeding among populations was proven using artificial pollination, geographical isolation and the high likelihood for self-pollination probably restricts gene flow and contributes to the phenotypic diversity observed in wild fennel populations.
The potential to produce and accumulate mono- and sesquiterpenes in lemon mint (Mentha aquatica var. citrata) glandular trichomes was evaluated. Volatiles were extracted using methyl-tert-butyl ether or solid phase micro extraction and determined by gas chromatography-mass spectrometry. The main components of the essential oil of lemon mint are the monoterpene alcohol linalool and its ester linalyl acetate. Sesquiterpenes, such as elemol, (E)-caryophyllene, and germacrene D, as well as the monoterpenes 1,8-cineole, β-myrcene, and β-(E)-ocimene, are also prominent. Most of the essential oil is localized in the glands, as leaves devoid of trichomes had very low essential oil levels. The quantities of all these components per leaf increased during leaf development until reaching the third whorl, and then the levels remained steady. Conversely, the essential oil content per gram fresh weight decreased with leaf development, but the decrease was not statistically significant at p = 0.05. Desalted cell-free extracts derived from isolated glandular trichomes were able to convert geranyl diphosphate into linalool. Lower amounts of geranyl diphosphate were also converted to other monoterpenes such as myrcene, α-pinene, β-pinene, limonene, β-(E)-ocimene, and nerol. Furthermore, the extracts were able to convert farnesyl diphosphate into the sesquiterpene (E)-caryophyllene and lesser amounts of other sesquiterpenes such as δ-cadinene, α-humulene, β-(E)-farnesene, and α-gurjunene. These cell-free extracts also efficiently catalyzed the formation of linalyl acetate from linalool and acetyl-coenzyme A. Our findings indicate that glandular trichomes of lemon mint, similar to other members of the Lamiaceae, contain unique enzymatic activities capable of the synthesis of mono- and sesquiterpene components of its essential oil.
Bitter fennel (Foeniculum vulgare Mill. var. vulgare, Apiaceae) is a common perennial hemicryptophyte, used since antiquity as a medicinal and aromatic herb in the Mediterranean basin. We describe the anatomical specialization and some of the factors that affect phenylpropene accumulation in the fruits of a t-anethole-rich chemotype during development. Histological examination of fruits by longitudinal sections indicated that each oil duct is an elongated cavity with a series of internal septa at 200-400 μm intervals. Oleoresin accumulation is accompanied by an increase in the oil duct area, as observed in transversal cross sections in early stages of development (from the yellow bud stage to the open flower stage). Upon maturation, oleoresin is further accumulated due to increased duct volume as a result of duct elongation. The main component of the oleoresin, t-anethole, is synthesized during flowering and in the early stages of fruit development, as monitored by the levels of S-adenosine methionine: t-anol O-methyltransferase activity. Upon transition from the waxy fruit stage (28 days after the yellow bud stage) to fully ripe fruit (42 days after the yellow bud stage) O-methyltransferase activity apparently ceases, indicating the cessation of de novo biosynthesis, while oleoresin levels remain constant, likely due to a lack of further metabolism and minimal volatilization, as indicated by apparent high lignification of the cells lining the oil ducts.
Melon (Cucumis melo L.) is highly polymorphic for fruit traits, providing seemingly endless possibilities for genetic improvement through introgression and recombination. By expanding our knowledge of genetic variation for various fruit-quality components and relationships among them, we have attempted to create novel combinations of desirable fruit characteristics. Our goal is to present a brief review of our activities and efforts to identify melon germplasm that is outstanding for one or more fruit-quality components, and we will discuss examples of new combinations and relationships. Fruit quality is determined primarily by taste and a major component of taste is content of sugar, particularly sucrose. Unlike most fruits eaten fresh, commercially available melons lack acidity. Using exotic melon germplasm, we have introgressed acidity into sweet melon, creating a new melon flavor, sweet-sour. Another component of fruit quality is nutritive value, particularly carotenoids and ascorbic acid (vitamin C). We surveyed approximately 350 melon accessions for fruit-quality components and identified several accessions that had consistently high sucrose content as well as high carotenoid and ascorbic acid contents. Aroma is yet another component of fruit quality and we have investigated the volatiles that affect the unique aromas of different melon cultivars, as well as some of the biochemical and molecular events that lead to their formation. Genomic resources have been developed, including a number of cDNA libraries representing the great polymorphism of the species, a collection of fruit-specific EST databases, and genetic maps.
Induced mutagenesis of agricultural crops creates new variation in genes, including those affecting agriculturally important traits such as plant morphology and fruit quality. Melon (Cucumis melo L.) is a diploid species (2n = 24) with a small genome, estimated as 450 Mb, but with relatively high levels of sequence and fruit shape polymorphism. We treated seeds of ‘Noy Yizre'el’, a ‘Galia’ melon-type parental line, with the chemical mutagen EMS (ethyl methane sulfonate). The resulting M1 plants were self-pollinated to produce about 3,000 M2 families, segregating for the induced mutations that we regard as a "mutation library". Phenotypic analyses revealed newly induced variation, mostly governed by single recessive mutations, affecting different plant organs, including cotyledon, leaves, flowers, and fruit, at different growth stages, from emergence to mature fruit. Several mutations show phenotypic similarities to mutations found in other plant species. Further studies are required to determine whether the same gene had been mutated in both species, indicating functional homology.
This mutation library is an important source for new traits. Some of the identified mutants have already been incorporated into our breeding program. Moreover, the melon mutation library serves as an essential infrastructure for the discovery of important genes, for the annotation of unknown sequences, and for phenotypic and genetic comparison with mutation libraries of other plant species.
Petals of 11 rose cultivars were analyzed by solvent extraction for the presence of key scent volatiles. Two different cultivars--'Fragrant Cloud', a very fragrant cultivar, and 'Golden Gate', a non-fragrant cultivar--were further analyzed by the headspace technique during flower opening. The 'Fragrant Cloud' headspace is composed of a variety of volatiles, including monoterpene alcohols, acetates, and terpene hydrocarbons, while the 'Golden Gate' headspace is composed mainly of orcinol dimethylether, a compound that is scentless to the human nose but that is perceived by honeybees, as judged by proboscis extension experiments. In both cultivars, the level of volatiles increased during flower development, while the ratio of different major volatiles remained constant.