PDF(Pubmed)
Abstract：
During leaf development, the timing of transition from cell proliferation to expansion is an important factor in determining the final organ size. However, the regulatory system involved in this transition remains less understood. To get an insight into this system, we investigated the compensation phenomenon, in which the cell number decreases while the cell size increases in organs with determinate growth. Compensation is observed in several plant species suggesting coordination between cell proliferation and expansion. In this study, we examined an Arabidopsis mutant of ANGUSTIFOLIA 3 (AN3)/GRF-INTERACTING FACTOR 1, a positive regulator of cell proliferation, which exhibits the compensation. Though the AN3 role has been extensively investigated, the mechanism underlying excess cell expansion in the an3 mutant remains unknown. Focusing on the early stage of leaf development, we performed kinematic, cytological, biochemical, and transcriptome analyses, and found that the cell size had already increased during the proliferation phase, with active cell proliferation in the an3 mutant. Moreover, at this stage, chloroplasts, vacuoles, and xylem cells developed earlier than in the wild-type cells. Transcriptome data showed that photosynthetic activity and secondary cell wall biosynthesis were activated in an3 proliferating cells. These results indicated that precocious cell differentiation occurs in an3 cells. Therefore, we suggest a novel AN3 role in the suppression of cell expansion/differentiation during the cell proliferation phase.
摘要：
在叶片发育过程中，从细胞增殖到扩增的过渡时间是决定最终器官大小的一个重要因素.然而,参与这一过渡的监管体系仍然知之甚少。为了深入了解这个系统，我们调查了补偿现象，其中在具有确定生长的器官中细胞数量减少而细胞大小增加。在几种植物物种中观察到补偿，表明细胞增殖和扩增之间存在协调。在这项研究中,我们检查了拟南芥突变体AN3（AN3）/GRF相互作用因子1，细胞增殖的正调节因子，它展示了补偿。虽然AN3的作用已经被广泛调查，在an3突变体中细胞过度扩增的潜在机制仍然未知。着眼于叶片发育的早期阶段，我们进行了运动学，细胞学，生物化学，和转录组分析，发现细胞大小在增殖阶段已经增加，在an3突变体中具有活跃的细胞增殖。此外，在这个阶段,叶绿体,空泡,木质部细胞发育比野生型细胞早。转录组数据显示，在3个增殖细胞中，光合活性和次生细胞壁生物合成被激活。这些结果表明早熟的细胞分化发生在细胞中。因此,我们提出了在细胞增殖阶段AN3在抑制细胞扩增/分化中的新作用.
