Zhang Juanjuan, Wang Xiao, Han Lu, Zhang Jing, Xie Yangyang, Li Jie, Wang Zeng-Yu, Wen Jiangqi, Mysore Kirankumar S, Zhou Chuanen
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.
New Phytol. 2022 Nov;236(4):1512-1528. doi: 10.1111/nph.18445. Epub 2022 Sep 16.
Stipule morphology is a classical botanical key character used in plant identification. Stipules are considerably diverse in size, function and architecture, such as leaf-like stipules, spines or tendrils. However, the molecular mechanism that regulates stipule identity remains largely unknown. We isolated mutants with abnormal stipules. The mutated gene encodes the NODULE ROOT1 (MtNOOT1), which is the ortholog of BLADE-ON-PETIOLE (BOP) in Medicago truncatula. We also obtained mutants of MtNOOT2, the homolog of MtNOOT1, but they do not show obvious defects in stipules. The mtnoot1 mtnoot2 double mutant shows a higher proportion of transformation from stipules to leaflet-like stipules than the single mutants, suggesting that they redundantly determine stipule identity. Further investigations show that MtNOOTs control stipule initiation together with SINGLE LEAFLET1 (SGL1), which functions in development of lateral leaflets. Increasing SGL1 activity in mtnoot1 mtnoot2 is sufficient for the transformation of stipules to leaves. Moreover, MtNOOTs inhibit SGL1 expression during stipule development, which is probably conserved in legume species. Our study proposes a genetic regulatory model for stipule development, specifically with regard to the MtNOOTs-SGL1 module, which functions in two phases of stipule development, first in the control of stipule initiation and second in stipule patterning.
托叶形态是植物鉴定中使用的经典植物学关键特征。托叶在大小、功能和结构上有很大差异，例如叶状托叶、刺或卷须。然而，调节托叶特征的分子机制在很大程度上仍然未知。我们分离出了托叶异常的突变体。突变基因编码根瘤根1（MtNOOT1），它是蒺藜苜蓿中叶柄上的叶片（BOP）的直系同源基因。我们还获得了MtNOOT1的同源基因MtNOOT2的突变体，但它们在托叶上没有表现出明显缺陷。mtnoot1 mtnoot2双突变体与单突变体相比，从托叶转变为小叶状托叶的比例更高，这表明它们在确定托叶特征方面存在冗余作用。进一步研究表明，MtNOOTs与在侧生小叶发育中起作用的单小叶1（SGL1）一起控制托叶起始。在mtnoot1 mtnoot2中增加SGL1的活性足以使托叶转变为叶片。此外，MtNOOTs在托叶发育过程中抑制SGL1的表达，这可能在豆科植物中是保守的。我们的研究提出了一个托叶发育的遗传调控模型，特别是关于MtNOOTs - SGL1模块，它在托叶发育的两个阶段起作用，首先是控制托叶起始，其次是托叶模式形成。
