State Key Laboratory of Crop Genetics and Germplasm Enhancement, Key Laboratory of Biology and Germplasm Enhancement of Horticultural Crops in East China, Ministry of Agriculture, Department of Horticulture, Nanjing Agricultural University, Nanjing 210095, China.
Department of Life Science, Nanjing Agricultural University, Nanjing 210095, China.
Plant Cell Physiol. 2020 Apr 1;61(4):761-774. doi: 10.1093/pcp/pcz238.
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. In this study, 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 shows altered hormone levels, which was likely responsible for the increased drought resistance and the impaired powdery mildew resistance of this lineage. Our findings further our understanding on how autotetraploidy provides growth advantages to plants.
同源四倍体通常比其二倍体祖先表现出生长优势，因为它们增加了光合作用活性；然而，这种机制的潜在分子基础仍然难以捉摸。在这项研究中，我们旨在从生理、细胞和分子水平上对同源四倍体白菜（ Brassica rapa ssp. chinensis ）进行表征。同源四倍体白菜的叶片比二倍体厚，具有相对较大的细胞间隙和细胞大小，以及更大的基粒类囊体高度。光合数据表明，同源四倍体的相对电子传递率（rETR）明显高于二倍体白菜。转录组数据显示，参与“光合作用”生物过程和“类囊体”细胞成分的基因表达主要在同源四倍体中受到调节。总的来说，我们的研究结果表明，类囊体中 rETR 的增加有助于增加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 BrPetC 表达的增加有关，这可能是由组蛋白修饰改变引起的。BrPetC 在拟南芥中的异位表达导致 rETR 和生物量增加，而在 BrPetC 沉默的白菜中则减少。同源四倍体白菜还表现出改变的激素水平，这可能是该谱系抗旱性增强和白粉病抗性受损的原因。我们的研究结果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。
