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.
Bibliographical noteFunding Information:
We thank Prof. Chuanyou Li and Dr. Lei Deng for providing vectors of the tomato CRISPR/Cas9 system, Prof. Gang Wu and Dr. Yunmin Xu for seeds, and Prof. Yuval Eshed for information, materials, and insights. This work was supported by NSFC grants 31861143021 and 31825002, the Key Research Project of the Frontier Science of the Chinese Academy of Sciences grant ZDBS‐LY‐SM012, and ISF grants 248/19 and ISF‐NSFC 2407/18. Alon Israeli is grateful to the Azrieli Foundation for the award of an Azrieli Fellowship. kan1‐12 kan2
© 2020 Society for Experimental Biology and John Wiley & Sons Ltd
- Solanum lycopersicum
- compound leaf
- flower development
- leaf meristem