Talukder Shyamal K, Azhaguvel Perumal, Chekhovskiy Konstantin, Saha Malay C
Noble Research Institute, LLC, Ardmore, OK, United States of America.
PLoS One. 2018 Jan 17;13(1):e0191343. doi: 10.1371/journal.pone.0191343. eCollection 2018.
Tall fescue (Festuca arundinacea Schreb.) is an important cool-season perennial grass species used as forage and turf, and in conservation plantings. There are three morphotypes in hexaploid tall fescue: Continental, Mediterranean and Rhizomatous. This study was conducted to develop morphotype-specific molecular markers to distinguish Continental and Mediterranean tall fescues, and establish their relationships with other species of the Festuca genus for genomic inference. Chloroplast sequence variation and simple sequence repeat (SSR) polymorphism were explored in 12 genotypes of three tall fescue morphotypes and four Festuca species. Hypervariable chloroplast regions were retrieved by using 33 specifically designed primers followed by sequencing the PCR products. SSR polymorphism was studied using 144 tall fescue SSR primers. Four chloroplast (NFTCHL17, NFTCHL43, NFTCHL45 and NFTCHL48) and three SSR (nffa090, nffa204 and nffa338) markers were identified which can distinctly differentiate Continental and Mediterranean morphotypes. A primer pair, NFTCHL45, amplified a 47 bp deletion between the two morphotypes is being routinely used in the Noble Research Institute's core facility for morphotype discrimination. Both chloroplast sequence variation and SSR diversity showed a close association between Rhizomatous and Continental morphotypes, while the Mediterranean morphotype was in a distant clade. F. pratensis and F. arundinacea var. glaucescens, the P and G1G2 genome donors, respectively, were grouped with the Continental clade, and F. mairei (M1M2 genome) grouped with the Mediterranean clade in chloroplast sequence variation, while both F. pratensis and F. mairei formed independent clade in SSR analysis. Age estimation based on chloroplast sequence variation indicated that the Continental and Mediterranean clades might have been colonized independently during 0.65 ± 0.06 and 0.96 ± 0.1 million years ago (Mya) respectively. The findings of the study will enhance tall fescue breeding for persistence and productivity.
高羊茅（Festuca arundinacea Schreb.）是一种重要的冷季型多年生禾本科植物，用作饲料、草坪以及用于保护性种植。六倍体高羊茅有三种形态型：大陆型、地中海型和根茎型。本研究旨在开发形态型特异性分子标记以区分大陆型和地中海型高羊茅，并确定它们与羊茅属其他物种的关系用于基因组推断。在三种高羊茅形态型的12个基因型以及四个羊茅属物种中探究了叶绿体序列变异和简单序列重复（SSR）多态性。使用33条专门设计的引物检索高变叶绿体区域，随后对PCR产物进行测序。使用144条高羊茅SSR引物研究SSR多态性。鉴定出四个叶绿体（NFTCHL17、NFTCHL43、NFTCHL45和NFTCHL48）和三个SSR（nffa090、nffa204和nffa338）标记，它们可以明显区分大陆型和地中海型形态型。一对引物NFTCHL45扩增出两种形态型之间47 bp的缺失，该引物在诺布尔研究所的核心设施中常规用于形态型鉴别。叶绿体序列变异和SSR多样性均显示根茎型和大陆型形态型之间存在密切关联，而地中海型形态型处于较远的分支。分别作为P和G1G2基因组供体的草地羊茅和 glaucescens变种与大陆型分支聚在一起，而在叶绿体序列变异中，麦氏羊茅（M1M2基因组）与地中海型分支聚在一起，而在SSR分析中，草地羊茅和麦氏羊茅均形成独立分支。基于叶绿体序列变异的年代估计表明，大陆型和地中海型分支可能分别在0.65±0.06和0.96±0.1百万年前（Mya）独立定殖。该研究结果将提高高羊茅的持久性和生产力育种水平。
