應用ISSR分子標誌研究台灣檫樹之族群遺傳變異

Genetic Diversity in Sassafras randaiense (Hay.) Rehder (Lauraceae) Based on ISSR Fingerprinting

台灣樹Sassafras randaiense （Hay.） Rehder 為台灣特有種樟科（Lauraceae）植物，本研究運用簡單序列重複區間（inter-simple sequence repeat, ISSR）分子標誌分析族群之遺傳結構與多樣性。採集自7 處之自然分布區域共137 株樣木，使用8 個ISSR 引子進行PCR 擴增試驗獲得39 個條帶，多型性條帶有38 條（97.44%）。族群遺傳變異分析結果顯示台灣樹具有高歧異度（H=0.3438）與遺傳分化（Gst=0.2788），分子變異分析（AMOVA）結果顯示族群間變異成分16.47% （p<0.0001），族群內為83.53% （p<0.0001），族群遺傳變異主要成分來自於族群內；依遺傳變異矩陣與地理距離矩陣之相關性測驗（Mantel test）無顯著關聯（r=0.1542），歸群與主座標分析所顯示遺傳變異與地理親緣不具分布關係。本研究顯示族群遺傳變異主要來自地區族群內，為維持族群遺傳多樣性，在保育策略上建議在自然生育地區實施就地保育措施，避免濫伐等人為干擾。同時可選擇移地保育，進行各地區族群引種育林之遺傳交流，擴大種原資源保育。

Sassafras randaiense (Hay.) Rehder (Lauraceae) is an endemic species of Taiwan. We collected 137 individuals from 7 natural populations and examined ISSR fingerprintings of the DNA sequences. PCR amplification with 8 ISSR primers yielded 39 DNA fragments, of which 38 were polymorphic (97.44%). AMOVA revealed that variance component among the populations was 16.47% (p＜0.0001), while within population was 83.53% (p＜0.0001). Mantel test exhibited low correlation (r=0.2830, p=0.1542) between the genetic variation and the spatial distribution. Popgene analysis revealed high genetic diversity (H=0.3438) of the species and also high genetic differentiation among the populations (Gst=0.2788). Cluster analysis and the principal coordinate analysis (PCOA) revealed no significant correlation (r=0.6635 p=0.9995) between the genetic differentiation and the spatial distribution. The conservation strategy for the species is to maintain in situ biodiversity and further to raise its gene diversity by hybridization among the populations in ex situ conservation.