Polyploid origins in Gynostemma pentaphyllum (Cucurbitaceae) inferred from multiple gene sequences

Jiang, Ling-Yan, Qian, Zeng-Qiang, Guo, Zhi-Gang, Wang, Chong, and Zhao, Gui-Fang (2009) Polyploid origins in Gynostemma pentaphyllum (Cucurbitaceae) inferred from multiple gene sequences. Molecular Phylogenetics and Evolution, 52 (1). pp. 183-191.

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Abstract

The genus Gynostemma (Cucurbitaceae) constitutes a polyploid group of perennial creeping herbs, in whose evolution polyploidization is a key component. With the largest variety of cytotypes (2n = 22, 44, 66 and 88) in Gynostemma, G. pentaphyllum is also the most widespread species in this genus. In the present study, we inferred the origins of polyploids in G. pentaphyllum using sequences of the plastid intergenic spacers (trnL–trnF, psbB–psbF and rpl20–rps12) and cloned DNA sequences from two nuclear regions (RPB2 and nrDNA ITS). Phylogenetic analyses of the separate and the combined nuclear gene datasets all supported autoploid origins of polyploids in G. pentaphyllum. Three polyploid populations were more closely related, indicating that significant genetic differentiation may have occurred between diploids and polyploids. We concluded that polyploidization might be an important evolutionary mechanism in the diversification of G. pentaphyllum. On the other hand, no chloroplast DNA (cpDNA) variation was detected in ingroups except the octoploid DL 8x, which possessed a different cpDNA haplotype from the other populations of G. pentaphyllum. This can be explained by limited sample sizes, possible extinction of its diploid progenitors and/or the occurrence of chloroplast transfer through hybridization with other Gynostemma species. However, the distribution of cytotypes in G. pentaphyllum was not as typical as many other autopolyploid complexes. Polyploidization failed to contribute significantly to the expansion of its geographic range. The geographic distribution of diploids and polyploids in G. pentaphyllum may be associated with the past ecological environments of different areas, especially during the glacial period.

Item ID: 4849
Item Type: Article (Refereed Research - C1)
Keywords: Gynostemma pentaphyllum; plastid intergenic spacer; nrDNA ITS; RPB2; polyploidization; polyploid origin; cytotype distribution
ISSN: 1095-9513
Date Deposited: 25 Aug 2009 23:33
FoR Codes: 06 BIOLOGICAL SCIENCES > 0604 Genetics > 060411 Population, Ecological and Evolutionary Genetics @ 50%
06 BIOLOGICAL SCIENCES > 0603 Evolutionary Biology > 060310 Plant Systematics and Taxonomy @ 50%
SEO Codes: 97 EXPANDING KNOWLEDGE > 970106 Expanding Knowledge in the Biological Sciences @ 100%
Citation Count from Web of Science Web of Science 10
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