The Key Laboratory of Plant Development and Environmental Adaptation Biology, Ministry of Education, School of Life Science, Shandong University, Qingdao, 266237, China.
Grassland Agri-Husbandry Research Center, College of Grassland Science, Qingdao Agricultural University, Qingdao, 266109, China.
J Integr Plant Biol. 2023 Oct;65(10):2279-2291. doi: 10.1111/jipb.13549. Epub 2023 Sep 13.
Compound leaf development requires the coordination of genetic factors, hormones, and other signals. In this study, we explored the functions of Class Ⅱ KNOTTED-like homeobox (KNOXII) genes in the model leguminous plant Medicago truncatula. Phenotypic and genetic analyses suggest that MtKNOX4, 5 are able to repress leaflet formation, while MtKNOX3, 9, 10 are not involved in this developmental process. Further investigations have shown that MtKNOX4 represses the CK signal transduction, which is downstream of MtKNOXⅠ-mediated CK biosynthesis. Additionally, two boundary genes, FUSED COMPOUND LEAF1 (orthologue of Arabidopsis Class M KNOX) and NO APICAL MERISTEM (orthologue of Arabidopsis CUP-SHAPED COTYLEDON), are necessary for MtKNOX4-mediated compound leaf formation. These findings suggest, that among the members of MtKNOXⅡ, MtKNOX4 plays a crucial role in integrating the CK pathway and boundary regulators, providing new insights into the roles of MtKNOXⅡ in regulating the elaboration of compound leaves in M. truncatula.
复叶的发育需要遗传因素、激素和其他信号的协调。在这项研究中，我们探索了类Ⅱ KNOTTED 同源盒（KNOXII）基因在模式豆科植物蒺藜苜蓿中的功能。表型和遗传分析表明，MtKNOX4、5 能够抑制小叶的形成，而 MtKNOX3、9、10 不参与这一发育过程。进一步的研究表明，MtKNOX4 抑制了 CK 信号转导，而 CK 信号转导是 MtKNOXⅠ介导的 CK 生物合成的下游。此外，两个边界基因，融合复叶 1（拟南芥类 M KNOX 的同源物）和无顶端分生组织（拟南芥 CUP-SHAPED 子叶的同源物），对于 MtKNOX4 介导的复叶形成是必需的。这些发现表明，在 MtKNOXⅡ的成员中，MtKNOX4 在整合 CK 途径和边界调节剂方面起着关键作用，为 MtKNOXⅡ在调节蒺藜苜蓿复叶发育中的作用提供了新的见解。
