Autopolyploids often show growth advantages over their diploid progenitors because of their increased photosynthetic activity; however, the underlying molecular basis of such mechanism remains elusive. Here, we aimed to characterize autotetraploid pak choi (Brassica rapa ssp. chinensis) at the physiological, cellular, and molecular levels. Autotetraploid pak choi has thicker leaves than its diploid counterparts, with relatively larger intercellular spaces and cell size and greater grana thylakoid height. Photosynthetic data showed that the relative electron transport rate (rETR) was markedly higher in autotetraploid than in diploid pak choi. Transcriptomic data revealed that the expressions of genes involved in 'photosynthesis' biological process and 'thylakoids' cellular component were mainly regulated in autotetraploids. Overall, our findings suggested that the increased rETR in the thylakoids contributed to the increased photosynthetic capacity of autotetraploid leaves. Furthermore, we found that the enhanced rETR is associated with increased BrPetC expression, which is likely altered by histone modification. The ectopic expression of BrPetC in Arabidopsis thaliana led to increased rETR and biomass, which were decreased in BrPetC-silenced pak choi. Autotetraploid pak choi also show altered hormone levels, which was likely responsible for the increased drought resistance and impaired powdery mildew resistance of this lineage. Our findings further our understanding on how autotetraploidy provides growth advantages to plants.

中文翻译：

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增强的相对电子传输速率有助于增加四倍体白菜的光合作用能力。

由于它们的光合作用增强，因此自身多倍体通常比其二倍体祖细胞显示出生长优势。但是，这种机制的潜在分子基础仍然难以捉摸。在这里，我们旨在表征生理，细胞和分子水平的同源四倍体小白菜（Brassica rapa ssp。chinensis）。同源四倍体小白菜的叶子比对应的二倍体小白菜厚，具有相对较大的细胞间空间和细胞大小以及较大的类囊体高度。光合作用的数据表明，同四倍体的相对电子传递速率（rETR）明显高于二倍体的白菜。转录组数据显示，参与“光合作用”生物过程的基因表达和“类囊体”的细胞成分主要在同源四倍体中受到调节。总体，我们的发现表明类囊体中rETR的增加促进了同源四倍体叶片的光合作用能力。此外，我们发现增强的rETR与增加的BrPetC表达有关，这可能因组蛋白修饰而改变。在拟南芥中BrPetC的异位表达导致rETR和生物量增加，而在BrPetC沉默的小白菜中它们降低。同源四倍体的白菜也显示出激素水平的变化，这很可能是导致该谱系抗旱性增强和白粉病抗性受损的原因。我们的发现进一步加深了我们对同源四倍体如何为植物提供生长优势的理解。此外，我们发现增强的rETR与增加的BrPetC表达有关，这可能因组蛋白修饰而改变。在拟南芥中BrPetC的异位表达导致rETR和生物量增加，而在BrPetC沉默的小白菜中它们降低。同源四倍体的白菜也显示出激素水平的变化，这很可能是导致该谱系抗旱性增强和白粉病抗性受损的原因。我们的发现进一步加深了我们对同源四倍体如何为植物提供生长优势的理解。此外，我们发现增强的rETR与增加的BrPetC表达有关，这可能因组蛋白修饰而改变。在拟南芥中BrPetC的异位表达导致rETR和生物量增加，而在BrPetC沉默的青菜中rETR和生物量均降低。同源四倍体的白菜也显示出激素水平的变化，这很可能是导致该谱系抗旱性增强和白粉病抗性受损的原因。我们的发现进一步加深了我们对同源四倍体如何为植物提供生长优势的理解。同源四倍体的白菜也显示出激素水平的改变，这很可能是导致该谱系抗旱性增强和白粉病抗性受损的原因。我们的发现进一步加深了我们对同源四倍体如何为植物提供生长优势的理解。同源四倍体的白菜也显示出激素水平的改变，这很可能是导致该谱系抗旱性增强和白粉病抗性受损的原因。我们的发现进一步加深了我们对同源四倍体如何为植物提供生长优势的理解。