Location: Floral and Nursery Plants Research Unit
Title: A hybrid swarm population of Pinus densiflora x P. sylvestris hybrids inferred from sequence analysis of chloroplast DNA and morphological characters Authors
|Joung, Young Hee -|
|Hyun, Jung Oh -|
|Mu, Ding -|
|Luo, Juchun -|
|Lee, Do Hyung -|
|Kawahara, Takayuki -|
|Suh, Jeung Keun -|
Submitted to: Forestry Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 16, 2012
Publication Date: N/A
Interpretive Summary: The genus Pinus is one of the most widely distributed genera in the Northern Hemisphere. Pinus sylvestris (P. syl) is the most common pine from the Russian Far East to European countries. Pinus densiflora (P. den) is the most common species distributed in China, Korea, and Japan. Pinus sylvestris var. sylvestriformis occurs in a very confined area near Baihe, Jilin Province, China. However, the use of a hybrid formula, P. den × P. syl, rather than using an infraspecific taxon name based on either of the parental species was suggested based on the sequence information from microsatellite analysis. Significant variations in morphology were observed at a natural stand of Pinus sylvestris var. sylvestriformis in China, and it was believed that the populations could be a hybrid swarm. However, morphological characteristics observed in mature plants did not agree with the information obtained from the chloroplast DNA simple sequence repeats (cpDNA SSR). Therefore DNA was obtained from mature plants and seedling progeny to understand any correlations between morphological characteristics and DNA information to study the introgression and the existence of a swarm population. Based on this study, it is concluded that the majority of P. den × P. syl from Jilin, China evaluated in this study are of hybrid origin forming a hybrid swarm population.
Technical Abstract: To confirm a hybrid swarm population of Pinus densiflora × P. sylvestris in Jilin, China and to study whether shoot apex morphology of 4-year old seedlings can be correlated with the sequence of a chloroplast DNA simple sequence repeat marker (cpDNA SSR), needles and seeds from P. densiflora, P. sylvestris, and P. densiflora × P. sylvestris collected from natural stands or experimental stations were used. Total genomic DNA was extracted and subjected to sequence analysis of the pine cpDNA SSR marker Pt15169. Morphological characters from 4-year old seedlings did not correlate with sequence variants of this marker. Marker haplotypes from all P. sylvestris trees had a TCTA element that was absent from all sampled P. densiflora trees. However, both haplotype classes involving this insertion/deletion element were found in a P. densiflora × P. sylvestris population and its seedling progeny. It is concluded that the P. densiflora × P. sylvestris accessions sampled from Jilin, China resulted from bi-directional crosses, as evidenced by both species’ cpDNA haplotypes within the hybrid swarm population.