Nhat Vuong Quoc, Kazama Yusuke, Ishii Kotaro, Ohbu Sumie, Kunitake Hisato, Abe Tomoko, Hirano Tomonari
Faculty of Agriculture, University of Miyazaki, 1-1 Gakuen-Kibanadai Nishi, Miyazaki 889-2192, Japan.
Faculty of Bioscience and Biotechnology, Fukui Prefectural University, 4-1-1 Kenjojima, Matsuoka, Eiheiji-cho, Yoshida-gun, Fukui 910-1195, Japan.
Plants (Basel). 2021 Sep 10;10(9):1881. doi: 10.3390/plants10091881.
Two growth processes, cell proliferation and expansion, determine plant species-specific organ sizes. A large flower mutant in , (), was isolated from a mutant library. In the flowers, post-mitotic cell expansion and endoreduplication of nuclear DNA were promoted. The whole-genome resequencing and genetic analysis results showed that the loss of function in (), a mediator complex subunit, was responsible for the large flower phenotypes exhibited by . A phenotypic analysis of the mutant alleles in and the double mutants created by crossing with representative large flower mutants revealed that MED16 and MED25 share part of the negative petal size regulatory pathways. Furthermore, the double mutant analyses suggested that there were genetically independent pathways leading to cell size restrictions in the floral organs which were not related to the MED complex. Several double mutants also formed larger and heavier seeds than the wild type and single mutant plants, which indicated that MED16 was involved in seed size regulation. This study has revealed part of the size-regulatory network in flowers and seeds through analysis of the mutant, and that the size-regulation pathways are partially different between floral organs and seeds.
细胞增殖和扩张这两个生长过程决定了植物物种特异性器官的大小。从一个突变体文库中分离出了拟南芥中的一个大花突变体（lfy-5）。在lfy-5的花朵中，有丝分裂后细胞的扩张以及核DNA的核内复制得到了促进。全基因组重测序和遗传分析结果表明，中介体复合物亚基MED16（MEDIATOR16）功能丧失是导致lfy-5出现大花表型的原因。对MED16突变等位基因以及通过将MED16与代表性大花突变体杂交产生的双突变体进行表型分析，结果显示MED16和MED25共享部分负向花瓣大小调控途径。此外，双突变体分析表明，存在与中介体复合物无关的、在花器官中导致细胞大小受限的遗传上独立的途径。几个双突变体还形成了比野生型和单突变体植株更大、更重的种子，这表明MED16参与种子大小的调控。通过对lfy-5突变体的分析，本研究揭示了花和种子中部分大小调控网络，并且花器官和种子之间的大小调控途径存在部分差异。
