He Zhuoxian, Jiang Xiaoqi, Ratnasekera Disna, Grassi Fabrizio, Perera Udugahapattuwage, Lu Bao-Rong
Ministry of Education Key Laboratory for Biodiversity and Ecological Engineering, Department of Ecology and Evolutionary Biology, Fudan University, Shanghai, China.
Department of Agricultural Biology, Faculty of Agriculture, University of Ruhuna, Matara, Sri Lanka.
PLoS One. 2014 Dec 1;9(12):e112778. doi: 10.1371/journal.pone.0112778. eCollection 2014.
Increased infestation of weedy rice-a noxious agricultural pest has caused significant reduction of grain yield of cultivated rice (Oryza sativa) worldwide. Knowledge on genetic diversity and structure of weedy rice populations will facilitate the design of effective methods to control this weed by tracing its origins and dispersal patterns in a given region. To generate such knowledge, we studied genetic diversity and structure of 21 weedy rice populations from Sri Lanka based on 23 selected microsatellite (SSR) loci. Results indicated an exceptionally high level of within-population genetic diversity (He = 0.62) and limited among-population differentiation (Fst = 0.17) for this predominantly self-pollinating weed. UPGMA analysis showed a loose genetic affinity of the weedy rice populations in relation to their geographical locations, and no obvious genetic structure among populations across the country. This phenomenon was associated with the considerable amount of gene flow between populations. Limited admixture from STRUCTURE analyses suggested a very low level of hybridization (pollen-mediated gene flow) between populations. The abundant within-population genetic diversity coupled with limited population genetic structure and differentiation is likely caused by the considerable seed-mediated gene flow of weedy rice along with the long-distance exchange of farmer-saved rice seeds between weedy-rice contaminated regions in Sri Lanka. In addition to other effective weed management strategies, promoting the application of certified rice seeds with no weedy rice contamination should be the immediate action to significantly reduce the proliferation and infestation of this weed in rice ecosystems in countries with similar rice farming styles as in Sri Lanka.
杂草稻（一种有害农业害虫）侵染的增加已导致全球栽培稻（亚洲栽培稻）的谷物产量大幅下降。了解杂草稻种群的遗传多样性和结构，将有助于通过追踪其在特定区域的起源和扩散模式，设计出有效的杂草控制方法。为了获得此类知识，我们基于23个选定的微卫星（SSR）位点，研究了来自斯里兰卡的21个杂草稻种群的遗传多样性和结构。结果表明，对于这种主要自花授粉的杂草而言，其种群内遗传多样性水平异常高（He = 0.62），而种群间分化有限（Fst = 0.17）。UPGMA分析表明，杂草稻种群与其地理位置的遗传亲缘关系松散，全国种群间没有明显的遗传结构。这种现象与种群间大量的基因流动有关。STRUCTURE分析显示的有限混合表明种群间的杂交（花粉介导的基因流动）水平非常低。种群内丰富的遗传多样性，加上有限的种群遗传结构和分化，可能是由于杂草稻大量的种子介导的基因流动，以及斯里兰卡杂草稻污染地区之间农民留存水稻种子的远距离交换所致。除其他有效的杂草管理策略外，推广应用无杂草稻污染的认证水稻种子，应是在与斯里兰卡有相似水稻种植方式的国家显著减少这种杂草在水稻生态系统中的增殖和侵染的立即行动。
