Characterization of Leaf Essential Oil Composition of Homozygous and Heterozygous Citrus clementina Hort. Extan. and its Ancestors

Abstract

Clementine is a natural tangor, resulting from an interspecific cross between mandarin and sweet orange. Gametic embryogenesis, allowing the single-step development of complete homozygous line from the heterozygous parents, increases the efficiency of perennial crop breeding programs. Tri-haploids have been regenerated through pollen embryogenesis (specifically, by anther culture) of Citrus clementina Hort. ex Tan., cv. Nules. Two of them (HOMO1 and HOMO2) have been acclimatized and grafted in vivo in 2000. Research regarding the chemical characteristics of plant regenerated by pollen embryogenesis or gynogenesis are useful to study the “gametoclonal variation”, as well as for further application of haploidy technology in Citrus breeding. For these reasons and with the aim to characterize these homozygous clementine genotypes, in this study leaf essential oils were extracted by Clevenger apparatus and their chemical composition was investigated by capillary GC-MS, comparing them with oils obtained from the heterozygous plant and from its ancestors (clementine is a hybrid between sweet orange and mandarin). The obtained oil compositions, submitted to a statistical analysis, are partitioned into groups using principal components analysis (PCA) and, compared to those of both parents, distinguished in three major chemotypes sabinene/linalool, γ-terpinene and methyl N-methylanthranilate.