NO APICAL MERISTEM ( MtNAM ) regulates floral organ identity and lateral organ separation in Medicago truncatula

作者：Xiaofei Cheng, Jianling Peng, Junying Ma, Yuhong Tang, Rujin Chen, Kirankumar S. Mysore, Jiangqi Wen · 发表于：New Phytologist · 年份：2012 · DOI：10.1111/j.1469-8137.2012.04147.x · 被引用次数：91 · 研究领域：Plant Molecular Biology Research、Plant Reproductive Biology、Plant Parasitism and Resistance

• The CUP-SHAPED COTYLEDON (CUC)/NO APICAL MERISTEM (NAM) family of genes control boundary formation and lateral organ separation, which is critical for proper leaf and flower patterning. However, most downstream targets of CUC/NAM genes remain unclear. • In a forward screen of the tobacco retrotransposon1 (Tnt1) insertion population in Medicago truncatula, we isolated a weak allele of the no-apical-meristem mutant mtnam-2. Meanwhile, we regenerated a mature plant from the null allele mtnam-1. These materials allowed us to extensively characterize the function of MtNAM and its downstream genes. • MtNAM is highly expressed in vegetative shoot buds and inflorescence apices, specifically at boundaries between the shoot apical meristem and leaf/flower primordia. Mature plants of the regenerated null allele and the weak allele display remarkable floral phenotypes: floral whorls and organ numbers are reduced and the floral organ identity is compromised. Microarray and quantitative RT-PCR analyses revealed that all classes of floral homeotic genes are down-regulated in mtnam mutants. Mutations in MtNAM also lead to fused cotyledons and leaflets of the compound leaf as well as a defective shoot apical meristem. • Our results revealed that MtNAM shares the role of CUC/NAM family genes in lateral organ separation and compound leaf development, and is also required for floral organ identity and development.