AUTHOR=Wang Hongfeng , Xu Yiteng , Hong Limei , Zhang Xue , Wang Xiao , Zhang Jing , Ding Zhaojun , Meng Zhe , Wang Zeng-Yu , Long Ruicai , Yang Qingchuan , Kong Fanjiang , Han Lu , Zhou Chuanen 

TITLE=HEADLESS Regulates Auxin Response and Compound Leaf Morphogenesis in Medicago truncatula

JOURNAL=Frontiers in Plant Science

VOLUME=10

YEAR=2019

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2019.01024

DOI=10.3389/fpls.2019.01024

ISSN=1664-462X

ABSTRACT=<p>WUSCHEL (WUS) is thought to be required for the establishment of the shoot stem cell niche in <italic>Arabidopsis thaliana</italic>. <italic>HEADLESS</italic> (<italic>HDL</italic>), a gene that encodes a WUS-related homeobox family transcription factor, is thought to be the <italic>Medicago truncatula</italic> ortholog of the <italic>WUS</italic> gene. <italic>HDL</italic> plays conserved roles in shoot apical meristem (SAM) and axillary meristem (AM) maintenance. <italic>HDL</italic> is also involved in compound leaf morphogenesis in <italic>M. truncatula</italic>; however, its regulatory mechanism has not yet been explored. Here, the significance of <italic>HDL</italic> in leaf development was investigated. Unlike <italic>WUS</italic> in <italic>A. thaliana</italic>, <italic>HDL</italic> was transcribed not only in the SAM and AM but also in the leaf. Both the patterning of the compound leaves and the shape of the leaf margin in <italic>hdl</italic> mutant were abnormal. The transcriptional profile of the gene <italic>SLM1</italic>, which encodes an auxin efflux carrier, was impaired and the plants’ auxin response was compromised. Further investigations revealed that <italic>HDL</italic> positively regulated auxin response likely through the recruitment of MtTPL/MtTPRs into the HDL repressor complex. Its participation in auxin-dependent compound leaf morphogenesis is of interest in the context of the functional conservation and neo-functionalization of the products of <italic>WUS</italic> orthologs.</p>