An important hybrid zone: evidence for two natural homoploid hybrids among three Origanum species

Abstract

Based on combined results of different approaches we describe two new natural hybrids, Origanum x bilgilii Dirmenci, T. Yazici & Arabaci and O. x dumanii Dirmenci, Arabaci & T. Yazici from southern Turkey (Antalya). They have a common parent, Origanum saccatum. Morphology and pollen micromorphology of the collected plants were studied, and a comparison of one nuclear (nrITS) and one chloroplast (rpl32) DNA marker was performed. The ploidy level of the two hybrids was established by chromosome counts. Both hybrids have some morphological characters in the leaves. bracts, calyces and corollas that are intermediate between those of their parents. Surface sculpturing and pollen grain size and shape of the hybrids vary and differ to a certain degree from those of the parental species. Heterozygous loci were detected in nrITS sequences of both O. x bilgilii and O. x dumanii, while rpl32 sequences were uninformative. Both hybrids and their parents have the same chromosome number of 2n = 30.