Genetic diversity among synthetic hexaploid wheat accessions (Triticum aestivum) with resistance to several fungal diseases
Genetic diversity among synthetic hexaploid wheat accessions (Triticum aestivum) with resistance to several fungal diseases
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DOI：
10.1007/s10722-015-0312-9
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发表时间：
2016-12-01
影响因子：
2
通讯作者：
Rajaram, Sanjaya
中科院分区：
文献类型：
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作者：
Das, Modan K.;Bai, Guihua;Rajaram, Sanjaya
人工合成六倍体小麦(SHW)被认为是一种很好的载体，可以转移大量的遗传变异，特别是节节麦D基因组中存在的许多有用性状。(2n=2x=14，DD)改良栽培小麦(2n=6x=42，AABBDD)。本研究的目的是(1)利用扩增片段长度多态性(AFLP)和简单序列重复(SSR)标记对32份抗病材料进行遗传多样性评价；(2)鉴定聚合抗病基因的不同种质。这些含有D基因组不同来源的SHW是从墨西哥国际玉米和小麦改良中心小麦远缘杂交计划培育的大约1000份SHW材料中鉴定出来的。在32份SHW材料中，8份抗赤霉病，7份抗叶锈病，8份抗白叶枯病。Drechsler ex Dastur(syn.：Bipolaris sorokiniana(Sacc.)Shoem.，Helminthosporium sativum Pammel，King et Bakke)，其中7株对小麦黑斑病(SepVictoria tritici Roberge in Desmaz.)表现抗性，2株对枯萎病和叶锈病均表现抗性。筛选出17个EcoRI/MseI AFLP引物组合和27个高度多态的SSR标记，其中包括20个D基因组特异标记。在获得的703个AFLP片段中，225个片段在32份SHW材料中表现为多态。AFLP群体的多态信息含量变化范围为0.06~0.50，平均多态信息含量为0.24。SSR分析的主等位基因频率在0.23~0.81之间，平均为0.45。SSR标记每个座位的等位基因数在3~15个之间，平均为7.4个。SSR标记的平均基因多样性和PIC分别为0.69和0.66，其中D基因组特异标记的PIC最高。聚类分析表明，所研究的SHW材料之间存在明显的类群。来自AFLP和SSR分析的距离矩阵之间的Mantel统计显示出中等但显著的相关性(r=0.52**)。结果表明，所研究的SHW材料具有丰富的遗传多样性，是改良小麦抗赤霉病、叶锈病、黑斑病和黑斑病的有价值的前期育种材料。最具多样性的SHW材料可用于聚合不同病害的抗性基因。
Synthetic hexaploid wheat (SHW) is known to be an excellent vehicle for transferring large genetic variations especially the many useful traits present in the D genome of Aegilops tauschii Coss. (2n = 2x = 14, DD) for improvement of cultivated wheat (Triticum aestivum L., 2n = 6x = 42, AABBDD). The objectives of the present study were to (1) evaluate genetic diversity among 32 selected SHW accessions with resistance to several fungal diseases using Amplified Fragment Length Polymorphism (AFLP) and Simple Sequence Repeat (SSR) markers and (2) identify diverse SHWs for pyramiding genes conferring resistance to different diseases. These SHWs containing different accessional sources of the D genome were identified from about 1000 SHW accessions developed by the Wheat Wide Crosses program at the International Maize and Wheat Improvement Center, Mexico. Of the 32 SHW accessions eight had resistance to Fusarium head blight (Fusarium graminearum Schw.), seven were resistant to leaf rust (Puccinia triticina Eriks.), eight resistant to Helminthosporium spot blotch [Cochliobolus sativus (Ito et Kurib.) Drechsler ex Dastur (syn.: Bipolaris sorokiniana (Sacc.) Shoem., Helminthosporium sativum Pammel, King et Bakke)], seven resistant to Septoria tritici blotch (Septoria tritici Roberge in Desmaz.), while two were resistant to both Fusarium head blight and leaf rust. Seventeen EcoRI/MseI AFLP primer combinations and 27 highly polymorphic SSR markers including 20 D genome specific markers were screened over all 32 SHW accessions. Among the 703 AFLP fragments scored, 225 were polymorphic across the 32 SHW accessions. Polymorphic information content (PIC) among the SHWs for AFLP ranged from 0.06 to 0.50 with an average PIC of 0.24. Major allelic frequency from SSR analysis ranged from 0.23 to 0.81 with an average of 0.45. Number of alleles per locus for the SSR markers ranged from 3 to 15 with an average allele number of 7.4. Average gene diversity and PIC for the SSR markers was 0.69 and 0.66, respectively, with the highest values being for the D genome specific markers. Cluster analysis showed distinct groups among the SHW accessions studied. Mantel statistics between the distance matrices from AFLP and SSR analyses showed a moderate but significant correlation (r = 0.52**). Our results indicate that the SHW accessions studied possess substantial genetic diversity and are valuable user-friendly pre-breeding materials for breeding improvement of wheat with resistance to Fusarium head blight, leaf rust, Helminthosporium spot blotch, and Septoria tritici blotch. The most diverse SHW accessions can be used for pyramiding resistance genes for different diseases.