Moretzsohn Márcio C, Barbosa Andrea V G, Alves-Freitas Dione M T, Teixeira Cristiane, Leal-Bertioli Soraya C M, Guimarães Patrícia M, Pereira Rinaldo W, Lopes Catalina R, Cavallari Marcelo M, Valls José F M, Bertioli David J, Gimenes Marcos A
Embrapa Recursos Genéticos e Biotecnologia, Brasília, DF, Brazil.
BMC Plant Biol. 2009 Apr 7;9:40. doi: 10.1186/1471-2229-9-40.
Arachis hypogaea (peanut) is an important crop worldwide, being mostly used for edible oil production, direct consumption and animal feed. Cultivated peanut is an allotetraploid species with two different genome components, A and B. Genetic linkage maps can greatly assist molecular breeding and genomic studies. However, the development of linkage maps for A. hypogaea is difficult because it has very low levels of polymorphism. This can be overcome by the utilization of wild species of Arachis, which present the A- and B-genomes in the diploid state, and show high levels of genetic variability.
In this work, we constructed a B-genome linkage map, which will complement the previously published map for the A-genome of Arachis, and produced an entire framework for the tetraploid genome. This map is based on an F2 population of 93 individuals obtained from the cross between the diploid A. ipaënsis (K30076) and the closely related A. magna (K30097), the former species being the most probable B genome donor to cultivated peanut. In spite of being classified as different species, the parents showed high crossability and relatively low polymorphism (22.3%), compared to other interspecific crosses. The map has 10 linkage groups, with 149 loci spanning a total map distance of 1,294 cM. The microsatellite markers utilized, developed for other Arachis species, showed high transferability (81.7%). Segregation distortion was 21.5%. This B-genome map was compared to the A-genome map using 51 common markers, revealing a high degree of synteny between both genomes.
The development of genetic maps for Arachis diploid wild species with A- and B-genomes effectively provides a genetic map for the tetraploid cultivated peanut in two separate diploid components and is a significant advance towards the construction of a transferable reference map for Arachis. Additionally, we were able to identify affinities of some Arachis linkage groups with Medicago truncatula, which will allow the transfer of information from the nearly-complete genome sequences of this model legume to the peanut crop.
落花生是全球一种重要的作物，主要用于生产食用油、直接食用和作为动物饲料。栽培花生是一种异源四倍体物种，具有两种不同的基因组成分，A和B。遗传连锁图谱可以极大地辅助分子育种和基因组研究。然而，由于落花生的多态性水平非常低，其连锁图谱的构建很困难。利用花生的野生种可以克服这一问题，这些野生种以二倍体状态呈现A和B基因组，并且表现出高水平的遗传变异性。
在这项研究中，我们构建了一个B基因组连锁图谱，它将补充之前发表的花生A基因组图谱，并为四倍体基因组生成一个完整的框架。该图谱基于从二倍体A. ipaënsis（K30076）与亲缘关系密切的A. magna（K30097）杂交获得的93个个体的F2群体，前一个物种是栽培花生最可能的B基因组供体。尽管这两个亲本被归类为不同的物种，但与其他种间杂交相比，它们表现出较高的杂交亲和性和相对较低的多态性（22.3%）。该图谱有10个连锁群，149个位点，总图距为1294厘摩。所使用的微卫星标记是为其他花生物种开发的，显示出较高的可转移性（81.7%）。分离畸变率为21.5%。使用51个共同标记将这个B基因组图谱与A基因组图谱进行比较，揭示了两个基因组之间高度的共线性。
为具有A和B基因组的花生二倍体野生种构建遗传图谱有效地为四倍体栽培花生在两个独立的二倍体成分中提供了遗传图谱，是朝着构建花生可转移参考图谱迈出的重要一步。此外，我们能够确定一些花生连锁群与蒺藜苜蓿的亲缘关系，这将使从这种模式豆科植物几乎完整的基因组序列中获取的信息转移到花生作物中。
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