Nicasio Tusa

Citrus somatic hybrid leaf essential oil

The essential oil from the leaves of a Citrus interspecific somatic hybrid obtained by symmetric protoplast fusion between ‘Milam’ lemon [purported sexual hybrid of C. Jambhiri Lush (×) C. sinensis] and ‘Femminello’ lemon (C. limon L. Burm f.) has been characterized by steam distillation GC–MS analysis and its composition compared with that of the corresponding oils obtained from the parent plants. The amount (%) of the different classes of substances present in the oils show, in the new hybrid, an overall lowering of the hydrocarbon fraction and an increase of the oxygenated components. The somatic hybrid shows a close similarity in the amounts of terpenes, sesquiterpenes and alcohols with the ‘Milam’ parent and in the amount of aldehydes with the other parent. Remaining oxygenated components appear lower in the hybrid with respect to both parents. Because of their genetic origins, the hybrid cells possess the nuclear genome of both parents and should potentially maintain all their genetic traits. However, the closer similarities found in the composition of the essential oils in the leaves of the somatic hybrid and the ‘Milam’ parent could be interpreted as the dominance, in the nucleus, of the genetic information from this parent, although possible interactions between the nucleus and the mitochondrial genome cannot be at present accounted for since the origin of the latter is uncertain. Copyright

Citrus cybrid leaf essential oil.

The essential oil from the leaves of a Citrus cybrid plant, obtained by somatic hybridization between ‘Valencia’ sweet orange (Citrus sinensis L. Osbeck), embryogenic parent, and ‘Femminello’ lemon (C. limon L. Burm f.), leaf parent, has been studied by steam distillation and GC–MS analysis and compared with the correspondent oils from the parent plants. Although the overall composition of the cybrid essential oil appears much closer to that of ‘Femminello’, the relatively higher percentage of β-caryophyllene, as well as the qualitative and quantitative modifications of the esteric fraction, are characteristic of the new hybrid. Since cybrid cells possess the nuclear genome of the mesophyll parent, ‘Femminello’ lemon, and the mitochondrial genome of the nucellar parent, ‘Valencia’ sweet orange, it seems possible to conclude that the genetic information coding for the biosynthesis of the essential oils is mainly embedded in the nucleus, although interactions between nuclear genome and cytoplasmic genome can not be excluded. Copyright

Analysis of volatile compounds released from embryogenic cultures and somatic embryos of sweet oranges by head space SPME

Volatile compounds released from callus and nucellar embryo tissues of ‘Valencia late’ and ‘Washington Navel’ sweet oranges (Citrus sinensis, L. Osbeck) were collected/concentrated by head space solid phase micro extraction and analysed by gas chromatography-mass spectrometry. Friable, white embryogenic cultures released a number of volatile compounds, including some essential oils. Different samples of the same embryogenic culture showed variability, possibly related to the presence of tissues undergoing differentiation. Analyses of the somatic embryos permitted the identification of several components, including limonene and methyl anthranilate. Considering the simplicity and the very small sample required (0.3 g of fresh tissue) head space solid phase micro extraction is suitable for studies and comparisons of volatile metabolites released from in vitro Citrus tissue cultures suggesting its potential in Citrus biochemical, genetic and breeding research.