Department of Biology, University of New Mexico, Albuquerque, NM USA.
Department of Biology, Luther College, Decorah, IA USA.
Ann Bot. 2018 Jun 8;121(7):1309-1318. doi: 10.1093/aob/mcy028.
Genome size is hypothesized to affect invasiveness in plants. Key evidence comes from a previous study of invasive eastern North American populations of the grass Phalaris arundinacea: invasive genotypes with smaller genomes had higher growth rates, and genome sizes were smaller in the invasive vs. native range. This study aimed to re-investigate those patterns by examining a broader range of North American populations and by employing the modern best-practice protocol for plant genome size estimation in addition to the previously used protocol.
Genome sizes were measured using both internal and pseudo-internal standardization protocols for 20 invasive and nine native range accessions of P. arundinacea. After a round of vegetative propagation to reduce maternal environmental effects, growth (stem elongation) rates of these accessions were measured in the greenhouse.
Using the best-practice protocol, there was no evidence of a correlation between genome size and growth rates (P = 0.704), and no evidence for differences in genome sizes of invasive and native range accessions (P > 0.353). However, using the older genome size estimation protocol, both relationships were significant (reproducing the results of the previous study).
Genome size reduction has not driven increased invasiveness in a broad sample of North American P. arundinacea. Further, inappropriate genome size estimation techniques can create spurious correlations between genome size and plant traits such as growth rate. Valid estimation is vital to progress in understanding the potentially widespread effects of genome size on biological processes and patterns.
基因组大小被假设会影响植物的入侵性。主要证据来自先前对北美东部地区雀稗属植物的研究：具有较小基因组的入侵基因型具有更高的生长速率，并且在入侵范围与原生范围相比，基因组大小更小。本研究旨在通过检查更广泛的北美种群，并采用现代最佳实践的植物基因组大小估计方法来重新研究这些模式，此外还采用了先前使用的方法。
使用内部和伪内部标准化方案测量了雀稗属的 20 个入侵和 9 个原生范围的样本的基因组大小。在一轮营养繁殖以减少母体环境影响后，在温室中测量了这些样本的生长（茎伸长）速率。
使用最佳实践方案，没有证据表明基因组大小与生长速率之间存在相关性（P = 0.704），也没有证据表明入侵和原生范围样本的基因组大小存在差异（P > 0.353）。然而，使用旧的基因组大小估计方案，这两种关系都具有显著意义（重现了先前研究的结果）。
在北美雀稗属的广泛样本中，基因组大小的减少并没有导致入侵性的增加。此外，不适当的基因组大小估计技术会在基因组大小与植物特征（如生长速率）之间产生虚假相关性。正确的估计对于理解基因组大小对生物过程和模式的潜在广泛影响至关重要。
