Department of Plant Sciences, University of California, Davis, CA 95616, USA.
Ann Bot. 2010 Apr;105(4):535-54. doi: 10.1093/aob/mcq009. Epub 2010 Feb 13.
Two closely related, wild tomato-like nightshade species, Solanum lycopersicoides and Solanum sitiens, inhabit a small area within the Atacama Desert region of Peru and Chile. Each species possesses unique traits, including abiotic and biotic stress tolerances, and can be hybridized with cultivated tomato. Conservation and utilization of these tomato relatives would benefit from an understanding of genetic diversity and relationships within and between populations.
Levels of genetic diversity and population genetic structure were investigated by genotyping representative accessions of each species with a set of simple sequence repeat (SSR) and allozyme markers.
As expected for self-incompatible species, populations of S. lycopersicoides and S. sitiens were relatively diverse, but contained less diversity than the wild tomato Solanum chilense, a related allogamous species native to this region. Populations of S. lycopersicoides were slightly more diverse than populations of S. sitiens according to SSRs, but the opposite trend was found with allozymes. A higher coefficient of inbreeding was noted in S. sitiens. A pattern of isolation by distance was evident in both species, consistent with the highly fragmented nature of the populations in situ. The populations of each taxon showed strong geographical structure, with evidence for three major groups, corresponding to the northern, central and southern elements of their respective distributions.
This information should be useful for optimizing regeneration strategies, for sampling of the populations for genes of interest, and for guiding future in situ conservation efforts.
两种密切相关的野生番茄状茄属植物，Solanum lycopersicoides 和 Solanum sitiens，栖息在秘鲁和智利的阿塔卡马沙漠地区的一个小区域内。每个物种都具有独特的特征，包括对非生物和生物胁迫的耐受性，并且可以与栽培番茄杂交。为了保护和利用这些番茄近缘种，需要了解种群内和种群间的遗传多样性和关系。
通过用一组简单序列重复（SSR）和同工酶标记对每个物种的代表性样本进行基因分型，研究了遗传多样性和种群遗传结构的水平。
正如自交不亲和物种所预期的那样，S. lycopersicoides 和 S. sitiens 的种群相对多样化，但与本地区的同源异花授粉物种野生番茄 Solanum chilense 相比，多样性较少。根据 SSRs，S. lycopersicoides 的种群比 S. sitiens 的种群略多样化，但同工酶的趋势相反。S. sitiens 的近交系数较高。两种物种都存在明显的距离隔离模式，与种群在原地高度碎片化的性质一致。每个分类群的种群表现出强烈的地理结构，有三个主要群体的证据，与各自分布的北部、中部和南部元素相对应。
这些信息对于优化再生策略、为感兴趣的基因进行种群采样以及指导未来的原地保护工作应该是有用的。
