Laboratory of Plant Ecology, University of Leuven, Arenbergpark 31, 3001 Heverlee, Belgium.
Ann Bot. 2010 May;105(5):769-76. doi: 10.1093/aob/mcq042. Epub 2010 Mar 12.
Clonal growth is a common phenomenon in plants and allows them to persist when sexual life-cycle completion is impeded. Very low levels of recruitment from seed will ultimately result in low levels of genotypic diversity. The situation can be expected to be exacerbated in spatially isolated populations of obligated allogamous species, as low genotypic diversities will result in low availability of compatible genotypes and low reproductive success. Populations of the self-incompatible forest herb lily-of-the-valley (Convallaria majalis) were studied with the aim of inferring the relative importance of sexual and asexual recruitment. Then the aim was to establish a relationship between genotypic diversity, sexual reproduction and the local forest environment.
Highly polymorphic microsatellite markers were used to investigate clonal diversities and population genetic structure of 20 populations of C. majalis in central Belgium.
Most of the populations studied consisted of a single genotype and linkage disequilibrium within populations was high, manifesting clonal growth as the main mode of reproduction. A population consisting of multiple genotypes mainly occurred in locations with a thin litter layer and high soil phosphorus levels, suggesting environment-mediated sporadic recruitment from seed. Highly significant genetic differentiation indicated that populations are reproductively isolated. In agreement with the self-incompatibility of C. majalis, monoclonal populations showed very low or even absent fruit set.
Lack of sexual recruitment in spatially isolated C. majalis populations has resulted in almost monoclonal populations with reduced or absent sexual reproduction, potentially constraining their long-term persistence. The local forest environment may play an important role in mediating sexual recruitment in clonal forest plant species.
克隆生长是植物中的一种常见现象，当有性生命周期完成受阻时，它使植物能够存活。极低水平的种子繁殖最终会导致基因型多样性水平降低。这种情况预计会在空间隔离的 obligate 异交物种种群中加剧，因为低基因型多样性将导致可用的相容基因型数量减少和繁殖成功率降低。本研究以自交不亲和的森林草本铃兰（Convallaria majalis）种群为研究对象，旨在推断有性和无性繁殖的相对重要性。然后，目的是建立基因型多样性、有性繁殖与当地森林环境之间的关系。
使用高度多态性微卫星标记来调查 20 个种群的铃兰的克隆多样性和种群遗传结构。
研究的大多数种群由单个基因型组成，种群内的连锁不平衡程度很高，表现出克隆生长是主要的繁殖方式。一个由多个基因型组成的种群主要出现在枯枝落叶层较薄且土壤磷含量较高的位置，表明环境介导的零星种子繁殖。高度显著的遗传分化表明种群是生殖隔离的。与铃兰的自交不亲和性一致，单细胞种群的果实结实率非常低甚至不存在。
在空间隔离的铃兰种群中缺乏有性繁殖导致了几乎是克隆的种群，有性繁殖减少或不存在，这可能限制了它们的长期生存。当地森林环境可能在调节克隆森林植物物种的有性繁殖方面发挥重要作用。
