Chromosome numbers and polyploidy inLeontopodium(Asteraceae: Gnaphalieae) from the Qinghai-Tibet Plateau of S.W. China

Abstract

Leontopodium R. Br. ex Cass. is the second largest genus within the Asian Gnaphalieae (Asteraceae) and is most diversified on the Qinghai-Tibet Plateau and its adjacent areas of SW China. The chromosome numbers and karyomorphology of five species from this region were investigated for the first time: Leontopodium sinense (2n = 28 = 22m + 6sm), L. muscoides (2n = 24 = 22m + 2sm), L. souliei (2n = 52 = 32m + 20sm), L. pusillum (2n = 72 = 52m + 20sm), and L. nanum (2n = 48 = 24m + 24sm). The results suggest that the basic chromosome number of Leontopodium is x = 14, followed with dysploidy numbers (e.g. x = 12, 13). Polyploidization has also played an important role in the evolution of Leontopodium in this region.

New or rare data on chromosome numbers and karyomorphology of some taxa in the subgenusSeriphidium(Bess.) Rouy. (Artemisia, Asteraceae) in Turkey

“…This shows that the A1 parameter is more useful for estimation of evolutionary relationships among some subgenera or sections of genus Artemisia. In contrast, Meng et al (2012) asserted that the changes in ploidy levels and karyotype asymmetry in genus Leontopodium are not necessarily coincident. They suggest not only that polyploidy and dysploidy play important roles during karyotype evolution and speciation, but also that ecological selection should be an alternative important factor for karyotype asymmetry.…”

“…Despite its relevance, the chromosome number is only known for around 25% of angiosperms (Stuessy 2009). The Asteraceae are one of the families in which major efforts towards chromosome number and genome size determination have been made (Watanabe et al 2007;Semple and Watanabe 2009;Meng et al 2012;Mousavi et al 2013;Olanj et al 2013;Khaldi et al 2014). In particular, hypotheses on basic chromosome numbers in Asteraceae have been hampered by a lack of understanding of which genera were basal within tribes and which tribes were basal within the family.…”

Chromosomal studies on the alpine genusDolomiaea(Asteraceae: Cardueae) from the Qinghai-Tibet Plateau and adjacent regions

“…Therefore, x = 18 appears to be the ancestral number in Dolomiaea and all related genera, and from this number, independent decreases led to x = 17 or other numbers in the different genera (Table 1, Figure 4). Similarly high basic chromosome numbers resulting from such paleopolyploidization events and aneuploid decreases also occurred in Ligularia and related genera (Liu 2004), Sinosenecio and related genera (Liu and Yang 2011), Leontopodium (Meng et al 2012) and a number of other genera or tribes (Robinson et al 1997;Carr et al 1999). …”

An overview of chromosome and basic numbers diversity in cytologically investigated polypetalous genera from the Western Himalayas (India)

“…The importance of polyploidy in evolution and speciation of plants has been emphasized by Kuwada (1915), Müntzing (1936), Darlington (1937), Löve and Löve (1949), Stebbins (1950Stebbins ( , 1971Stebbins ( , 1985, Wendel and Doyle (2005), Cui et al (2006), Otto (2007), Wood et al (2009) andMeng et al (2012). Polyploidy is an important process in the evolutionary history of plants and has a profound impact on biodiversity dynamics and ecosystem functioning (Wendel 2000;Ainouche and Jenczewski 2010).…”