Snodgrass S J, Jareczek J, Wendel J F
Department of Biology, Grinnell College, Grinnell, IA, USA.
Department of Ecology, Evolution, and Organismal Biology, Iowa State University, Ames, IA, USA.
AoB Plants. 2017 Jan 12;9(1). doi: 10.1093/aobpla/plw082. Print 2017 Jan.
Nucleotypic effects are phenotypic changes related to the total nuclear DNA amount per cell. These effects are commonly observed among and within genera for certain cell types, and the generality of the positive correlation between genome size and cell size has been well established. However, there are few studies of nucleotypic effects which incorporate into the analysis both ploidy level and genome size (given as Mbp determined by 2C values). To test the hypothesis that cell size scales with genome size and ploidy, we measured the guard cell length, epidermal pavement cell surface area, and pollen grain diameter using individuals of multiple species and accessions of the cotton genus (Gossypium), in which different species exhibit three-fold variation in genome size. We measured cell sizes using calibrated microscopic image analysis. Significant relationships were found between genome size and cell size, with stronger correlations between guard cell length and genome size than with epidermal pavement cell surface area. We also found a relationship between pollen grain diameter and genome size. These results indicate that nucleotypic effects occur within Gossypium, scale with ploidy level, and are stronger in less variable cell types.
核型效应是指与每个细胞的总核DNA量相关的表型变化。在某些细胞类型的属间和属内通常可以观察到这些效应，并且基因组大小与细胞大小之间正相关的普遍性已经得到充分证实。然而，很少有关于核型效应的研究将倍性水平和基因组大小（以通过2C值确定的Mbp表示）纳入分析。为了检验细胞大小与基因组大小和倍性相关的假设，我们使用棉属（陆地棉）多个物种和种质的个体测量了保卫细胞长度、表皮铺板细胞表面积和花粉粒直径，其中不同物种的基因组大小存在三倍的差异。我们使用校准的显微图像分析测量细胞大小。发现基因组大小与细胞大小之间存在显著关系，保卫细胞长度与基因组大小之间的相关性比与表皮铺板细胞表面积之间的相关性更强。我们还发现花粉粒直径与基因组大小之间存在关系。这些结果表明，核型效应在棉属内发生，与倍性水平相关，并且在变异性较小的细胞类型中更强。
