基于DNA條形碼的向日葵田彎管列當種群遺傳多樣性研究

張毅笑 魏守輝 姜翠蘭 黃兆峰 蘇杰天 孟帥帥 云曉鵬 白全江 吳文龍 黃紅娟

摘要 彎管列當是危害我國向日葵最嚴重的寄生雜草。為了明確我國向日葵田彎管列當種群的遺傳多樣性，本試驗利用rbcL、matK、ITS2條形碼序列對采自我國向日葵主產區的58份彎管列當樣品進行PCR擴增及測序，采用Vector NTI軟件對測序結果進行剪切比對，利用MEGA 6.0軟件計算種內遺傳距離并構建系統發育樹。利用掃描電鏡觀察其種子的顯微形態特征。結果表明，3個DNA 條形碼序列中僅ITS2片段擴增測序結果理想并表現出較好的聚類結果。各樣品ITS2序列剪切比對后長度為453 bp，種內遺傳距離為0.002～0.007，通過比較各樣品ITS2序列的堿基組成和差異位點，能將不同彎管列當種群區分開。ITS2聚類結果表明58份彎管列當樣品聚為3類，分別為Ⅰ型、Ⅱ型和Ⅲ型。形態分類結果表明，不同類型彎管列當在植株形態、種子形狀及微觀形態結構等方面存在差別。由于不同彎管列當種群的生境、寄主（向日葵栽培品種）不同，其種群遺傳進化差異顯著。基于ITS2 條形碼和掃描電鏡形態學觀察相結合的方法可用于彎管列當種群遺傳多樣性研究。

關鍵詞 彎管列當; DNA條形碼; ITS2序列; 種子形態; 遺傳多樣性

中圖分類號： S453

文獻標識碼： A

DOI： 10.16688/j.zwbh.2021039

Abstract Orobanche cernua Loefling is the most serious parasitic weed that threats the production of sunflower in China. To clarify the genetic diversity of different O.cernua populations in sunflower fields， barcode fragments of rbcL， matK and ITS2 were used for PCR amplification and sequencing of 58 samples of O.cernua collected from main sunflower-producing areas. The sequencing results were assembled using the Vector NTI software. MEGA 6.0 was used to calculate the intraspecific genetic distance and construct phylogenetic trees. The microscopic morphological characteristics of O.cernua seeds were observed by scanning electron microscope. The results showed that， among the three DNA barcodes， only the results of amplification and sequencing of ITS2 fragments were satisfactory and showed better clustering effect. The length of ITS2 sequences after shear alignment was 453 bp. The intraspecific genetic distance was 0.002-0.007. By comparing the base composition and differential sites of ITS2 sequences of each sample， different O.cernua populations could be distinguished. The clustering results of ITS2 showed that 58 samples of O.cernua were divided into three groups， which could be classified as type Ⅰ， Ⅱ and Ⅲ. The results of morphological classification showed that there were differences in plant morphology， seed shape and micro-morphological structure among different types. There were significant differences in the population genetic evolution among different O.cernua populations originated from different habitats and hosts （sunflower cultivars）. The method based on ITS2 barcoding and morphological observation by scanning electron microscope could be used to study the population genetic diversity of O.cernua.

Key words Orobanche cernua; DNA barcoding; ITS2 sequence; seed morphology; genetic diversity

彎管列當Orobanche cernua Loefling是列當科Orobanchaceae列當屬Orobanche的根部全寄生性雜草，廣泛分布于世界各地。在我國主要分布在吉林、內蒙古、河北、山西、陜西、甘肅、青海和新疆等地，可寄生在向日葵根上對其產量和品質造成嚴重危害[14]。彎管列當被認為是起源于保加利亞，寄主為菊科Asteraceae蒿屬Artemisia植物或禾谷類植物。……