Hinf-I digestion of cytochrome oxidase I region is not a diagnostic test for A. m. lamarckii

EVOLUTIONARY GENETICS

SHORT COMMUNICATION

Hinf-I digestion of cytochrome oxidase I region is not a diagnostic test for A. m. lamarckii

Irfan Kandemir^{I, II}; Maria A. Pinto^III; Marina D. Meixner^I; Walter S. Sheppard^I

^IDepartment of Entomology, Washington State University, Pullman, WA, USA

^IIDepartment of Biology, Karaelmas University, Zonguldak, Turkey

^IIICentro de Investigação de Montanha, Campus de Santa Apolónia, Bragança, Portugal

^{Send correspondence to}

ABSTRACT

Restriction fragment length polymorphism of whole mitochondrial DNA or PCR amplified mtDNA regions are known to be useful in discriminating among honey bee lineages and also some individual subspecies. In this study, PCR-amplified fragments of cytochrome oxidase I (CO-I) and cytochrome B (Cyt B) of honey bees sampled from different countries (Cyprus, Turkey, Ethiopia, Syria and Egypt) were digested with Hinf I and Bgl II restriction enzymes, respectively. Eastern Europe and Mediterranean honey bee subspecies were separated by the Cyt B/Bgl II analysis, although Hinf I digestion of the CO-I region yielded much finer resolution within different honey bee lineages. Here we report that CO-I/Hinf-I is a discriminative test for the mitochondrial "O" lineage, rather than a diagnostic site for A. m. lamarckii.

Key words: mtDNA, cytochrome oxidase I, Apis mellifera lamarckii, O lineage.

Based on multivariate statistical analysis of morphometric characteristics, 26 honey bee subspecies have been recognized, divided into four evolutionary lineages (Ruttner, 1988; 1992; Sheppard et al., 1997; Sheppard and Meixner, 2003). For the most part, these evolutionary groupings have been supported by mtDNA and microsatellite analysis (Cornuet and Garnery, 1991; Garnery et al., 1992; Estoup et al., 1995). Most individual subspecies cannot be distinguished based on current mtDNA or nuclear DNA protocols. However, PCR amplification of the COI-COII intergenic region and digestion with Dra-I restriction enzyme has proven useful to differentiate among some honey bee subspecies. There are other diagnostic sites useful to differentiate evolutionary lineages, group of subspecies and a few individual subspecies (Sheppard et al., 1994; Palmer et al., 2000; Sheppard and Smith, 2000; Pinto et al., 2003). One of these subspecies, A. m. lamarckii, has been reported to be distinguishable by CO-I region amplification and Hinf-I digestion (Nielsen et al., 2000). A. m. lamarckii was one of several African subspecies introduced into the United States prior to the arrival of Africanized honey bees (derived from A. m. scutellata). Here we investigated whether the phylogeographic distribution of this restriction fragment pattern is limited to A. m. lamarckii (Egypt) or whether it can be found in other subspecies including A. m. syriaca (Syria and Turkey), A. m. meda (Syria and Iran), A. m. cypria (Cyprus) and A. m. yemenitica (Ethiopia and Yemen).

Adult honey bee samples were collected from several countries, including Turkey (Kandemir et al., 2006), Northern Cyprus, Syria, Iran, Egypt and Ethiopia. Honey bees were stored either in 80% ethanol or frozen until laboratory analysis. Total nucleic acids were extracted following the methods of Sheppard and McPheron (1991) and Doyle and Doyle (1987). An approximately 1000 bp region of the cytochrome oxidase I (COI) gene and 800 bp region of the cytochrome B gene were amplified using primer pairs and PCR conditions previously reported (Sheppard et al., 1994; Nielsen et al., 2000; Crozier et al., 1991). After PCR, the amplified fragments for COI and CytB were digested with Hinf-I and Bgl II restriction enzymes, respectively, according to manufacturer's recommendations. Amplified PCR products were separated on a 1.5% agarose gel (Bio-Rad) and restriction enzyme digested fragments were separated on a 2.5% mixed agarose gel consisting of 1% agarose (Bio-Rad) and 1.5% Nu-Sieve agarose (Nu-Sieve). Gels were stained with ethidium bromide, destained with distilled water and photographed under UV light.

With the exception of some samples from Ethiopia, all samples analyzed by CytB amplification and Bgl II digestion (Cyt B/Bgl II) exhibited a two-banded mitochondrial restriction fragment pattern (mitotype). This mitotype is generally considered to exclude A. m. scutellata as the possible subspecies of origin. However, when the cytochrome oxidase I (CO I) region of the same samples was digested with Hinf I (CO I/Hinf I), further resolution of the middle eastern and east African honey bee population was achieved.

Out of 334 colonies from Turkey, 6 from the very southern end (within the geographic range of A. m. syriaca) showed the typical "A. m. lamarckii" CO I/Hinf I mitotype (Kandemir et al., 2006). Honey bee samples from northern Cyprus and Iran, A. m. cypria and A. m. meda, respectively, exhibited European mitotypes for both Cyt B/Bgl II and CO I/Hinf I digestions, except two of the A. m. cypria colonies which had the A. m. lamarckii CO I/Hinf I mitotype. All samples from Egypt (A. m. lamarckii) showed the A.m. lamarckii CO I/Hinf I mitotype. Out of 35 samples from Syria (A. m. syriaca), 28 of them had the A. m. lamarckii CO I/Hinf I mitotype. Out of 109 Ethiopian samples, eight had A. m. lamarckii mitotypes (Table 1).

The analysis of the COI-COII intergenic region of honey bees from Syria and Turkey showed similar mtDNA restriction fragment patterns as has been found in A. m. lamarckii. Palmer et al. (2000) mentioned the presence of a fourth mtDNA lineage, but did not discuss the similarity to A. m. lamarckii. Similar findings were reported by Franck et al. (2000) based on COI-COII analysis of Lebanese honey bees. The results of their analysis of the COI-COII intergenic region indicated that honey bees from Lebanon (A. m. syriaca) had the same Dra-I restriction digestion pattern found in A. m. lamarckii. Due to the distinction of this pattern from African (A) restriction fragment patterns (other than those found in Egypt), they designated these new restriction fragment patterns as belonging to a mitochondrial lineage O.

Our results show that the distribution of the CO I/Hinf I mitotype "typical" of A. m. lamarckii is not restricted to Egypt, but is dispersed along the Nile river south toward Ethiopia and to the east to Yemen on the Arabian Peninsula. To the north, it extends to Turkey where the mitotype was found in the Hatay province that borders to Syria. Quite likely, this mitotype occurs in Israel, Palestine and Jordan as well. Although morphological data supports the placement of A. m. lamarckii within the African lineage, accumulated molecular data appears to contradict this grouping and suggests placement of A. m. lamarckii within a distinctive lineage (Arias and Sheppard, 1996; Franck et al., 2000). The use of O as the designation for this distinctive mitochondrial lineage (Franck et al., 2000) may present confusion with the O morphological lineage described by Ruttner (1988). The distinctive morphological lineages C and O cannot be resolved easily using mitochondrial analysis and, thus, are both grouped within the C mtDNA lineage. Nonetheless, the "A. m. lamarckii" restriction fragment pattern (CO I/Hinf I) or "O" mitochondrial lineage (Franck et al., 2000) appears to be a widespread genetic variant. Further study of the distribution of this variant among the subspecies of the A and C morphological lineages will be important to fully understand the phylogeography of Apis mellifera.

Acknowledgements

This work was partially funded by TUBITAK-TBAG 2403, and BAYG-2219 scholarship to IK and by IFAFS Grant no. 2001-52103-11417 from the USDA-CSREES to WSS.

Received: November 1, 2005; Accepted: June 2, 2006.

Associate Editor: Klaus Hartfelder

References

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Publication Dates

• Publication in this collection
  21 Nov 2006
• Date of issue
  2006

History

• Received
  01 Nov 2005
• Accepted
  02 June 2006