Molecular phylogenetic data and seed coat morphology resolve the generic position of some Chenopodioideae (Chenopodiaceae-Amaranthaceae) with reduced perianth segmentsтезисы доклада

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1. Chenopodioideae_symposium.pdf Chenopodioideae_symposium.pdf 12,2 МБ 2 октября 2018 [Alexander-Sukhorukov]

[1] Molecular phylogenetic data and seed coat morphology resolve the generic position of some chenopodioideae (chenopodiaceae-amaranthaceae) with reduced perianth segments / A. P. Sukhorukov, M. V. Nilova, A. A. Krinitsina et al. // Caryophyllales 2018. — IBUNAM Mexico, 2018. The former Chenopodium subgen. Blitum and the genus Monolepis (Chenopodioideae) are characterized in part by a reduced (0–4) number of perianth segments. According to recent molecular phylogenetic studies these groups belong to the reinstated genera Blitum incl. Monolepis (tribe Anserineae) and Oxybasis (tribe Chenopodieae). However, key taxa such as Chenopodium antarcticum, C. exsuccum, C. litwinowii, C. foliosum subsp. montanum, and Monolepis spathulata were not included, and so their phylogenetic position within the Chenopodioideae remained equivocal. These species and additional samples of Blitum asiaticum and B. nuttallianum were incorporated into an expanded phylogenetic study based on nrDNA (ITS region) and cpDNA (trnL-trnF and atpB-rbcL intergenic spacers and rbcL gene). Analyses confirm the placement of C. exsuccum, C. litwinowii and C. foliosum subsp. montanum within Blitum (currently recognized as Blitum petiolare, B. litwinowii, and B. virgatum subsp. montanum respectively); additionally, Chenopodium antarcticum, currently known as Oxybasis antarctica, also placed within Blitum (reinstated here as B. antarcticum). Congruent with previous studies, two of the three accepted species of Monolepis – the type species M. trifida (= M. nuttalliana) as well as M. asiatica – are included in Blitum. The monotypic genus Carocarpidium described recently with the type C. californicum is not accepted as it is placed within Blitum (reinstated here as B. californicum). To date, few reliable morphological characters have been proposed that consistently distinguish Blitum (incl. two Monolepis species) from morphologically similar Oxybasis; however, two key differences are evident: (1) the presence of long-petiolate rosulate leaves in Blitum vs their absence in Oxybasis, and (2) a seed coat structure with the outer wall of the testa cells lacking stalactites (‘non-stalactite seed coat’) but with an obvious protoplast in Blitum vs seed coat with the outer walls of the testa cells having stalactites (‘stalactite seed coat’) and a reduced protoplast in Oxybasis. Surprisingly, the newly sequenced North American Monolepis spathulata nested within the tribe Dysphanieae (based on ITS and atpB-rbcL analyses) or sister to all Dysphanieae (trnL-trnF intergenic spacer). The phylogenetic results, as well as presence of the stalactites in the outer cell walls of the testa and lack of the rosulate leaves confirms the distinctiveness of Monolepis spathulata from all Blitum, and therefore the recent combination Blitum spathulatum is erroneous. Indeed, the morphological and molecular distinctiveness of this species from all Dysphanieae support its recognition as new monotypic genus.

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