Polyploidy and introgression in invasive giant knotweed (Fallopia sachalinensis) during the colonization of remote volcanic islands

• Published in: Scientific reports Vol. 8; no. 1; pp. 16021 - 9
• Main Authors: Park, Chong-Wook, Bhandari, Gauri Shankar, Won, Hyosig, Park, Jin Hee, Park, Daniel Sangsoon
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 30-10-2018; Nature Publishing Group; Nature Portfolio
• Subjects: 38/22; 38/23; 38/77; 45/29; 631/158/857; 631/181/457/649/2157; 631/181/757; 631/449/2669; Colonization; Fallopia Sachalinensis; Giant Knotweed; Haplotypes; Humanities and Social Sciences; Islands; Japonica Accessions; multidisciplinary; Polygonum sachalinense; Polyploidy; Sakhalin Island; Science; Science (multidisciplinary); Ullung Island; Volcanic islands; Japan; Fallopia Sachalinensis; Sakhalin Island; Japonica Accessions; Giant Knotweed; Ullung Island
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/s41598-018-34025-2

Invasive giant knotweed (
Fallopia sachalinensis
) is native to northeastern Asia. In Korea,
F. sachalinensis
is confined to two volcanic islands, Ullung and Dok islands, where it occurs as dodecaploids (2n = 132). We investigated the molecular variation in 104 accessions from 94 populations of
F. sachalinensis
and its relatives throughout their native range to elucidate the origin of these island populations. All
F. sachalinensis
plants on Ullung and Dok islands were uniquely dodecaploid, whereas other populations were tetraploid (2
n
 = 44). Among the 39 cpDNA haplotypes identified, the accessions from these islands shared two unique haplotypes, and were resolved as a well-supported monophyletic clade. However, this clade was sister to a clade comprising
F. japonica
accessions from southwestern Japan and separated from the clade comprising
F. sachalinensis
from other areas; this relationship is inconsistent with morphological evidence. The monophyly of the
F. sachalinensis
populations on Ullung and Dok islands suggests a single colonization event. The progenitor was likely from Japan, where it possibly captured
F. japonica
var.
japonica
cpDNA via introgression. The Ullung Island populations subsequently differentiated through polyploidization and mutations post-introduction. Our results also indicate that giant knotweed in Europe and North America likely originated from northern Japan and/or Sakhalin Island.