Hybridization among three Cirsium (Asteraceae) species and important evidence for three new hybrids from Turkey

Abstract

In this study, three new hybrids from the genus Cirsium are described for the first time. Cirsium xnezaketiae Yildiz, Dirmenci & Arabaci, C. xkelkitensis Yildiz, Arabaci & Dirmenci, and C. xerzincanicum Yildiz, Dirmenci & Arabaci are investigated in detail morphologically, palynologically, and molecularly. The hybrid individuals were detected on field trips due to their intermediate morphological characters. Their morphological properties were analyzed to compare with their parents. The pollen grain morphologies of the hybrids and their allies were investigated using light and a scanning electron microscope. The pollen grains were radially symmetrical, isopolar, trizonocolporate, and with echinate or scabrate sculpturing. The tectum is psilate/punctate, microreticulate, or ornate in sculpture. Dimorphic pollen grains were encountered in C. leucocephalum (Willd.) Spreng. subsp. leucocephalum. Two nuclear DNA regions were used to find single nucleotide polymorphisms. nrITS DNA data gave more information than nrETS data about polymorphism. In conclusion, C. xnezaketiae, C. xkelkitensis, and C. xerzincanicum exhibit some significant morphological, palynological, and molecular differences from their parents and present evidence of potential introgression hybridization. Since the hybrids live in a complex with their parents, and some parents have polymorphic loci like their putative hybrids, it can be presented as evidence for potential introgression since backcrossing may be possible among taxa.