Isolation, annotation and applications of expressed sequence tags from the olive fly, Bactrocera oleae

Abstract

The olive fruit fly, Bactrocera oleae, is the major pest of the olive tree. Despite its importance, very little genetic and molecular knowledge is available. The present study is a first attempt to identify and characterize B. oleae expressed sequence tags (ESTs). One hundred and ninety-five randomly selected cDNA clones were isolated and the obtained sequences were annotated through BLASTX similarity searches. A set of 159 unique putative transcripts were functionally assigned using Gene Ontology terms in broad categories of biological process, molecular function and cellular component based on D. melanogaster matches. Moreover, the cytogenetic location of 35 ESTs was determined by in situ hybridization to B. oleae polytene chromosomes. The resulting low-resolution EST map more than doubles the available entry points to the insect's genome and can assist syntenic comparisons with other distant species. The deduced codon usage of the isolated ESTs suggested a conserved pattern of B. oleae with its closest relatives. Additionally, the comparative analysis of B. oleae ESTs with the homologous D. melanogaster genes led to the development of 17 nuclear EPIC-PCR markers for the amplification of intron sequences of 11 Tephritidae species. Sequencing analysis of several cross-amplified intron sequences revealed a high degree of conservation among Bactrocera species and a varying transferability of the generated markers across the examined genera, suggesting that this method can provide a useful tool for the clarification of phylogenetic relationships among different species, particularly in cases of species complexes.

Genetic and cytogenetic analysis of the American cherry fruit fly, Rhagoletis cingulata (Diptera: Tephritidae)

“…3, 4, 7, 8) and R. ceraci respective chromosomes (Kounatidis et al 2008). The identification of chromosomal homologies in the three Rhagoletis species further supports the suggestion that chromosome elements tend to maintain their essential identity even among distantly related Diptera, despite the long divergence time (Foster et al 1981;Malacrida et al 1986;Zacharopoulou et al 1992;Tsoumani et al 2011;Drosopoulou et al 2011).…”

Cytogenetic analysis of the Ethiopian fruit fly Dacus ciliatus (Diptera: Tephritidae)

“…Recently, the same chromosome homologies have been observed in B. dorsalis (Zacharopoulou et al 2011). Thus, the existence of chromosomal homologies among D. ciliatus, B. oleae, B. dorsalis, B. tryoni, and C. capitata (Zambetaki et al 1995;Zhao et al 1998;Mavragani-Tsipidou 2002;Zacharopoulou et al 2011), as well as between C. capitata and D. melanogaster Gariou-Papalexiou et al 2002) and B. oleae and D. melanogaster (Tsoumani et al 2011) further supports the suggestion that chromosome elements tend to maintain their essential identity even among distantly related Diptera, despite the long divergence time (Foster et al 1981;Malacrida et al 1986;Zacharopoulou et al 1992).…”

Μοριακή ανάλυση της δομής και της οργάνωσης του γονιδιώματος του σημαντικότερου παράσιτου της ελιάς, του εντόμου Bactrocera oleae

“…Συγκεκριμένα το γονιδίωμα του δάκου εμφανίζεται συγκριτικά μεγαλύτερο από της D. melanogaster και στα ίδια περίπου επίπεδα με της M. domestica (295 ± 10 Mb), ενώ αξιοσημείωτη είναι η διαφορά του με την C. capitata. Τα δύο αυτά είδη της οικογένειας Tephritidae εμφανίζουν διακριτή διαφορά μεγέθους σε επίπεδο γονιδιώματος, εφόσον το μέγεθος του γονιδιώματος της C. capitata έχει καθοριστεί κατά προσέγγιση ίσο με 591 Μb (Tsoumani & Mathiopoulos 2011). Η μεγάλη απόκλιση μεταξύ των μεγεθών των γονιδιωμάτων τους υποδηλώνει κατ' επέκταση τη διαφοροποίηση της οργάνωσης και της δομής των γονιδιωμάτων των δύο ειδών.…”

“…Contrary to the medfly, its genetics and genomics is relatively poorly developed, a fact that has hindered the development of effective SIT-based approaches to its control . However, recent advances in particular gene systems Kakani et al , 2011, cytogenetics (for a review see Mavragani-Tsipidou 2002), population structure , Nardi et al, 2010), genetic transformation ) and EST markers (Tsoumani et al 2011), give promise that alternative control approaches may soon be developed.…”

“…Although homologies between polytene chromosomal segments of both species have already been assigned ) and cytogenetic maps have been constructed (for revised maps see Stratikopoulos et al 2008;Tsoumani et al 2011), it is still necessary to generate denser and therefore more informative genetic maps for interspecies comparisons. Differences in structure of intergenic regions and introns, which have been demonstrated in previous cross-species analyses of microsatellite and EPIC markers Stratikopoulos et al 2009;Tsoumani et al 2011), as well as identified speciesspecific repeats Tsoumani unpublished data) are factors contributing to their different genome structure. Thus, the observed differences in their genome size reflect the considerable chromosomal reorganization and the variation in their repetitive DNA during their evolutionary divergence.…”