Intergeneric hybridization between Hippolytia kaschgarica (Krascheninnikov) Poljakov and Nipponanthemum nipponicum (Franch. ex Maxim.) Kitam.

Abstract

An intergeneric hybrid between Hippolytiakaschgarica (maternal plant) and Nipponanthemum nipponicum (paternal plant) was produced without emasculation for the first time. This proves a close relationship between Hippolytia and Nipponanthemum, once again. The hybrids could be identified by nuclear ribosomal DNA internal transcribed spacer (ITS) sequences and morphological characteristics. The composition of the hybrid capitulum was a mix between both parents. It was basically similar to the maternal plant (Hippolytia) with yellow (actinomorphic) tubular florets, but supplemented with 5–13 white tetramerous, or pentamerous tubular florets bursting out in the outer whirl, being more distinctive and bigger. Instead of ligulate white ray florets of the paternal plant (Nipponanthemum), they were tubular (actinomorphic). The same phenomenon recently appeared in the intergeneric hybrid between Cancrinia maximowiczii (tubular) and the interspecific hybrid of Chrysanthemum naktongense × Chrysanthemum ×morifolium ‘Aifen’ (ligulate, daisy-like). The shape of the achenes of our new hybrid is quite similar to that of the paternal parent with pappus of separate unequal subulate scales, or awns. In the maternal parent, pappus is absent. Similarly to the referred intergeneric hybrid, this new viable hybrid might be used as bridge for breeding multi-generic hybrids within the Compositae tribe Anthemideae. Since the molecular mechanism behind the novel phenotype of the new hybrid has not been explored in Chrysanthemum, this is discussed here with recent findings in Senecio, Gerbera and Helianthus. One of the CYCLOIDEA-like genes that control floral symmetry, CYC2c is required for zygomorphy in normal ligulate ray florets. In novel intergeneric hybrids, ray florets remain actinomorphic (tubular), however. Some causes are tackled.