Transfer of genes from a coastal oak species to an inland one enables the latter to colonize the coastal habitat

Environment-dependent introgression from Quercus dentata to a coastal ecotype of Q. mongolica var. crispula in northern Japan.

Teruyoshi Nagamitsu (a), Kentaro Uchiyama (b), Ayako Izuno (b), Hajime Shimizu (c), Atsushi Nakanishi (a)

(a) Hokkaido Research Center, FFPRI, Sapporo, Hokkaido, Japan.

(b) Department of Forest Molecular Genetics and Biotechnology, FFPRI, Tsukuba, Ibaraki, Japan.

(c) Hokkaido Research Organization, Bibai, Hokkaido, Japan.

New Phytologist、Wiley、August 2019 DOI：10.1111/nph.16131( External link )

In northern Japan, Quercus dentata (Qd) grows in coastal forests, whereas Quercus mongolica var. crispula (Qc) grows in inland forests. In Hokkaido, the northernmost part of Japan, there is a northern limit of the distributional range of Qd. Beyond the limit, Qc grows in coastal forests. This coastal ecotype of Qc has unique characters, such as thick shoots and thick leaves with rounded serrations and dense hairs, which are similar to Qd. The origin of the coastal Qc ecotype has not been clarified.

We determined the genotypes at genome-wide loci using the reference sequences of Quercus robur genome and found alleles transferred from Qd to the coastal Qc ecotype. These alleles were moved through interspecific hybridization between Qd and Qc and multiple generations of back-crossing to Qc.

The transfer of alleles, so-called introgression, from a species in a specific habitat to another species is considered to enable the latter species to colonize the habitat of the former species. Our findings showed an example of such environment-dependent introgression in oaks.

Photo: Leaves, shoots, and acorns. Left, inland oak, Qc; middle, coastal ecotype of Qc; right, coastal oak, Qd.