Voigt-Zielinski Marie-Luise, Piwczyński Marcin, Sharbel Timothy F
Apomixis Research Group, Department of Cytogenetics and Genome Analysis, Leibniz Institute of Plant Genetics and Crop Plant Research, 06466, Gatersleben, Germany.
Sex Plant Reprod. 2012 Jun;25(2):97-109. doi: 10.1007/s00497-012-0181-8. Epub 2012 Feb 25.
The co-occurrence of apomixis (asexual reproduction) and polyploidy in plants has been the subject of debate in regard to the origin and evolution of asexuality. In recent years, polyploidy has been postulated as a maintenance and stabilization factor rather than as a source of apomixis origin. It is assumed polyploidy facilitates the compensation for mutation accumulation, and hence, the rare occurrence of diploid apomixis indirectly supports this finding. Nevertheless, diploid apomicts exist and are successful, especially in the genus Boechera. While comparing phenotypic traits, fitness-related traits and apomixis penetrance between both diploid and triploid apomicts in the genus Boechera, it was expected to find trait variance that can be attributed to ploidy. Surprisingly, little trait variation could be assigned to ploidy, but rather trait variations were mainly genotype-specific. Additionally, it is shown that paternal contribution is very important for trait success, even though all offspring are genetically identical to the mother plant. This harbors implications for the introduction of apomixis into crop plants, considering the effects of paternal contribution during asexual reproduction. Nevertheless, polyploidy is an efficient way to buffer deleterious mutations, but the flexibility of diploid apomicts of the genus Boechera for rare sexual events contributes to their success in nature.
植物中无融合生殖（无性繁殖）与多倍体的共存一直是无性繁殖起源与进化方面的争论焦点。近年来，多倍体被假定为一种维持和稳定因素，而非无融合生殖起源的源头。据推测，多倍体有助于补偿突变积累，因此，二倍体无融合生殖的罕见发生间接支持了这一发现。然而，二倍体无融合生殖植物确实存在且很成功，尤其是在岩生紫罗兰属中。在比较岩生紫罗兰属中二倍体和三倍体无融合生殖植物的表型性状、与适合度相关的性状以及无融合生殖的外显率时，预计会发现可归因于倍性的性状差异。令人惊讶的是，几乎没有性状差异可归因于倍性，相反，性状差异主要是基因型特异性的。此外，研究表明，父本贡献对性状成功非常重要，尽管所有后代在基因上都与母本植物相同。考虑到无性繁殖过程中父本贡献的影响，这对将无融合生殖引入农作物具有启示意义。尽管如此，多倍体是缓冲有害突变的有效方式，但岩生紫罗兰属二倍体无融合生殖植物在罕见有性事件中的灵活性促成了它们在自然界的成功。
