Leaflet initiation and blade expansion are separable in compound leaf development

Fei Du*, Yajin Mo, Alon Israeli, Qingqing Wang, Tamar Yifhar, Naomi Ori, Yuling Jiao

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

20 Scopus citations


Compound leaves are composed of multiple separate blade units termed leaflets. In tomato (Solanum lycopersicum) compound leaves, auxin promotes both leaflet initiation and blade expansion. However, it is unclear how these two developmental processes interact. With highly variable complexity, tomato compound leaves provide an ideal system to address this question. In this study, we obtained and analyzed mutants of the WUSCHEL-RELATED HOMEOBOX (WOX) family gene SlLAM1 from tomato, whose orthologs in tobacco (Nicotiana sylvestris) and other species are indispensable for blade expansion. We show that SlLAM1 is expressed in the middle and marginal domains of leaves, and is required for blade expansion in leaflets. We demonstrate that sllam1 mutants cause a delay of leaflet initiation and slightly alter the arrangement of first-order leaflets, whereas the overall leaflet number is comparable to that of wild-type leaves. Analysis of the genetic interactions between SlLAM1 and key auxin signaling components revealed an epistatic effect of SlLAM1 in determining the final leaf form. Finally, we show that SlLAM1 is also required for floral organ growth and affects the fertility of gametophytes. Our data suggest that SlLAM1 promotes blade expansion in multiple leaf types, and leaflet initiation can be largely uncoupled from blade expansion during compound leaf morphogenesis.

Original languageAmerican English
Pages (from-to)1073-1087
Number of pages15
JournalPlant Journal
Issue number4
StatePublished - Nov 2020

Bibliographical note

Publisher Copyright:
© 2020 Society for Experimental Biology and John Wiley & Sons Ltd


  • SlLAM1
  • SlWOX1
  • Solanum lycopersicum
  • auxin
  • blastozone
  • compound leaf
  • flower development
  • leaf meristem
  • tomato


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