STM/BP-Like KNOXI Is Uncoupled from ARP in the Regulation of Compound Leaf Development in Medicago truncatula

Chuanen Zhou; Lu Han; Guifen Li; Maofeng Chai; Chunxiang Fu; Xiaofei Cheng; Jiangqi Wen; Yuhong Tang; Zeng-Yu Wang

doi:10.1105/tpc.114.123885

STM/BP-Like KNOXI Is Uncoupled from ARP in the Regulation of Compound Leaf Development in Medicago truncatula

Plant Cell. 2014 Apr;26(4):1464-1479. doi: 10.1105/tpc.114.123885. Epub 2014 Apr 29.

Authors

Chuanen Zhou¹, Lu Han², Guifen Li³, Maofeng Chai⁴, Chunxiang Fu⁴, Xiaofei Cheng³, Jiangqi Wen³, Yuhong Tang³, Zeng-Yu Wang⁵

Affiliations

¹ Forage Improvement Division, The Samuel Roberts Noble Foundation, Ardmore, Oklahoma 73401 Key Laboratory of Plant Cell Engineering and Germplasm Innovation, Ministry of Education, School of Life Science, Shandong University, Jinan, Shandong 250100, P.R. China.
² School of Medical and Life Science, University of Jinan, Jinan, Shandong 250022, P.R. China.
³ Plant Biology Division, The Samuel Roberts Noble Foundation, Ardmore, Oklahoma 73401.
⁴ Forage Improvement Division, The Samuel Roberts Noble Foundation, Ardmore, Oklahoma 73401.
⁵ Forage Improvement Division, The Samuel Roberts Noble Foundation, Ardmore, Oklahoma 73401 zywang@noble.org.

Abstract

Class I KNOTTED-like homeobox (KNOXI) genes are critical for the maintenance of the shoot apical meristem. The expression domain of KNOXI is regulated by ASYMMETRIC LEAVES1/ROUGHSHEATH2/PHANTASTICA (ARP) genes, which are associated with leaf morphology. In the inverted repeat-lacking clade (IRLC) of Fabaceae, the orthologs of LEAFY (LFY) function in place of KNOXI to regulate compound leaf development. Here, we characterized loss-of-function mutants of ARP (PHAN) and SHOOTMERISTEMLESS (STM)- and BREVIPEDICELLUS (BP)-like KNOXI in the model IRLC legume species Medicago truncatula. The function of ARP genes is species specific. The repression of STM/BP-like KNOXI genes in leaves is not mediated by PHAN, and no suppression of PHAN by STM/BP-like KNOXI genes was observed either, indicating that STM/BP-like KNOXI genes are uncoupled from PHAN in M. truncatula. Furthermore, comparative analyses of phenotypic output in response to ectopic expression of KNOXI and the M. truncatula LFY ortholog, SINGLE LEAFLET1 (SGL1), reveal that KNOXI and SGL1 regulate parallel pathways in leaf development. We propose that SGL1 probably functions in a stage-specific manner in the regulation of the indeterminate state of developing leaves in M. truncatula.