Abstract
The class B MADS-box genes belong to two distinct functional groups: the AP3/DEF-like and the PI/GLO-like sub-families. In orchids, AP3/DEF-like genes are present in four copies, each with a different role in floral organ formation, which is described in the “orchid code” model. Interestingly, the orchid PI/GLO-like genes are present in two copies in Orchidinae, whereas they are described as single copy in the other orchid lineages. The two PI/GLO-like paralogs have site-specific different selective constraints; in addition, they show relaxation of purifying selection when compared to the single-copy lineages. In this study, we present a comparative analysis of the expression patterns of the two PI/GLO-like paralogs, OrcPI and OrcPI2, in floral tissues of Orchis italica in different developmental stages using real-time PCR. The two genes show similar expression profiles in the tissue examined, with differences detectable between immature and mature inflorescence. In all cases, OrcPI2 is expressed at a higher level than OrcPI. Real-time PCR results reveal that the co-expression of the two duplicated loci could have a fully or partially redundant function. The possible evolutionary fate of OrcPI and OrcPI2 is discussed as well as their involvement in ovary development.
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Acknowledgements
The authors are grateful to Prof. Salvatore Cozzolino and Dr. Giuseppe Pavarese for plant material and manual pollination of the O. italica ovaries. The authors thank Mr. Vincenzo Iacueo and Mrs Rosaria Terracciano for technical support. This work was supported by the Campania Region Grant L.R. N.5/2002, year 2007, “Evolutionary analysis of flower development in orchids: genetic characterization of the MADS-box locus OrcPI.”
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Salemme, M., Sica, M., Gaudio, L. et al. Expression pattern of two paralogs of the PI/GLO-like locus during Orchis italica (Orchidaceae, Orchidinae) flower development. Dev Genes Evol 221, 241–246 (2011). https://doi.org/10.1007/s00427-011-0372-6
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DOI: https://doi.org/10.1007/s00427-011-0372-6