Ploidy and Size at Multiple Scales in the Arabidopsis Sepal

First author: Dana Olivia Robinson; Affiliations: Cornell University (康奈尔大学): Ithaca, USA

Corresponding author: Adrienne H. K. Roeder

Ploidy (倍性) and size phenomena are observed to be correlated across several biological scales, from subcellular to organismal. Two kinds of ploidy change can affect plants. Whole-genome multiplication increases ploidy in whole plants and is broadly associated with increases in cell and organism size. Endoreduplication (核内复制) increases ploidy in individual cells. Ploidy increase is strongly correlated with increased cell size and nuclear volume. Here, we investigate scaling relationships between ploidy and size by simultaneously quantifying nuclear size, cell size, and organ size in sepals from an isogenic (等基因系) series of diploid, tetraploid, and octoploid (八倍体) Arabidopsis thaliana plants, each of which contains an internal endopolyploidy (核内多倍性) series. We find that pavement cell size and transcriptome size increase linearly with whole-organism ploidy, but organ area increases more modestly due to a compensatory (补偿性的) decrease in cell number. We observe that cell size and nuclear size are maintained at a constant ratio; the value of this constant is similar in diploid and tetraploid plants, and slightly lower in octoploid plants. However, cell size is maintained in a mutant with reduced nuclear size, indicating that cell size is scaled to cell ploidy rather than to nuclear size. These results shed light on how size is regulated in plants and how cells and organisms of differing sizes are generated by ploidy change.

染色体倍性及大小与从亚细胞到整个生物体等不同层面的生物过程均有着非常密切的关系。两类倍性的变化能够影响植物，一类是全基因组范围的染色体加倍，这会显著增加细胞和植物个体的大小；另外一类是染色体在核内的复制，这会增加单个细胞的倍性。倍性的增加与细胞大小和核容积的增加有这非常密切的联系。本文通过同时测量等基因系拟南芥二倍体、四倍体及八倍体的萼片中细胞核大小、细胞大小和器官大小来研究倍性和大小之间的关系，不同倍性的拟南芥均有核内多倍性株系。作者发现细胞大小和转录组大小与整个植株染色体的倍性有着线性相关，但器官大小的增加更多的是由于细胞数量的减少所做的补偿性行为。作者还观察到细胞大小和核大小维持在一个恒定的比例上，二倍体和四倍体中这种比例相当，而八倍体中这种比例稍低。然而，细胞大小在一个细胞核变小的突变体中没有变化，说明相对于核大小，细胞倍性更有可能影响细胞的大小。本文的结果显示了植株大小是如何被调控的，以及不同大小的细胞和器官是如何通过倍性的变化所产生的。

通讯：Adrienne Roeder (http://roeder.wicmb.cornell.edu)

研究方向：植物细胞大小的产生和发育；植物生殖器官大小和形态的形成。

doi: https://doi.org/10.1105/tpc.18.00344

Journal: Plant Cell

First Published: 24 August, 2018

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