Abstract Detail

Systematics Section/ASPT

Chung, Kuo-Fang [1], Yang, Hsun-An [2], Hoch, Peter [3], Peng, Ching-I [2].

Untangling the north temperate haplostemonous Ludwigia (Onagraceae).

The north-temperate haplostemonous (NTHap) Ludwigia (sect.Ludwigia, Isnardia, Microcarpium, and Miquelia), characterized by pluriseriate and free seeds and glabrous and convex nectarines, is a polyploidy complex (2X, 4X, 6X, and 8X) of 24 species known to hybridize extensively at both inter- and intrasectional levels. To test hypotheses regarding their hybrid origins and polyploidizations, molecular phylogenies were reconstructed based on nuclear gene PgiC and chloroplast(trnL-trnF and rpL16) DNA sequences.For PgiC gene, each NThap Ludwigia species possess the expected number of gene copies according to their ploidy level. In the PgiC gene tree, gene copies of sect. Ludwigia (all diploid) forms a robust clade sister to the strongly supported clade composed of the gene copies sampled from sect. Isnardia, Microcarpium, and Miquelia. Within the later clade, gene copies of the North American sections (sect. Isnarida and Microcarpium) are grouped into 5 subclades, likely corresponding to the genome A, B (or H), C (or I), D (or H),and F proposed previously based on cytological ground. The PgiC gene supports that all tetraploid species of sect. Microcarpium (L. suffruticosa, L.lanceolata, L. sphaerocarpa, L. pilosa, L. ravenii, and L. glandulosa)are allotetraploid between L. palustrisor its ancestor of genome A (♀) and genome B (or H). The hexaploid Ludwigia alata (sect. Microcarpium) is most likely derived from hybrids between the diploid L.microcarpa (genome D or H; ♀) of sect. Microcarpium and L.lanceolata/sphaerocarpa (♂).The two tetraploids of sect. Isnardia are derived from different genomes: Ludwigiaspathulata derived from hybrids between genome D (or H; ♀) and genome A (e.g., L.palustrus; genome A; ♂) and L.arcuata derived from hybrids between genome C (or I) and genome B (or H).No living relatives of genome C and B are known. The two hexaploid species of sect. Isnardia (L. repens and L. brevipes)are most likely derived from hybrid between L.arcuata (♀) and L. palustris (♂)while the hybridization of L. arcuata(♀) and L. microcarpa (♂) gave rise to the hexaploid L. simpsonii of sect. Microcarpium. The octoploid L. curtisii of sect. Microcarpium is most likely derived from hybrids between L. simpsonii (♀) and L. liniolia (genome F; ♂) of sect. Microcarpium.

Broader Impacts:

1 - National Taiwan University, No. 1, Sec. 4, Roosevelt Road, Taipei, N/A, 10617, Taiwan
2 - Academia Sinica, Biodiversity Research Center, 128 Academia Road, Section 2, Taipei, 115, Taiwan
3 - Missouri Botanical Garden, P.O. Box 299, St. Louis, MO, 63166, USA

Keywords:
polyploidization
hybridization
Gene duplication.

Presentation Type: Oral Paper:Papers for Sections
Session: 18
Location: Franklin A/Hyatt
Date: Monday, July 9th, 2012
Time: 4:00 PM
Number: 18010
Abstract ID:878