The WOX family transcriptional regulator SlLAM1 controls compound leaf and floral organ development inSolanum lycopersicum

Abstract

Plant-specific WOX family transcription factors play important roles ranging from embryogenesis to lateral organ development. The WOX1 transcription factors, which belong to the modern clade of the WOX family, are known to regulate outgrowth of the leaf blade specifically in the mediolateral axis; however, the role of WOX1 in compound leaf development remains unknown. Phylogenetic analysis of the whole WOX family in tomato (Solanum lycopersicum) indicates that there are 10 members that represent the modern, intermediate, and ancient clades. Using phylogenetic analysis and a reverse genetic approach, in this study we identified SlLAM1 in the modern clade and examined its function and tissue-specific expression pattern. We found that knocking out SlLAM1 via CRISPR/Cas9-mediated genome editing led to narrow leaves and a reduced number of secondary leaflets. Overexpression of tomato SlLAM1 could rescue the defects of the tobacco lam1 mutant. Anatomical and transcriptomic analyses demonstrated that floral organ development, fruit size, secondary leaflet initiation, and leaf complexity were altered due to loss-of-function of SlLAM1. These findings demonstrate that tomato SlLAM1 plays an important role in the regulation of secondary leaflet initiation, in addition to its conserved function in blade expansion.

Leaf form diversification in an ornamental heirloom tomato results from alterations in two different HOMEOBOX genes

“…CR-wox1-1 plants showed narrower leaves (Figures 4B and 4C) and lower LVD than M82 (Figure 4D), matching the phenotype described in wox1 mutants in other species 18,19 and tomato mutants, unfused flower (uf), and SlLAM1. [21][22][23] We noticed that these phenotypes were similar to those of the classical tomato mutant, solanifolia (sf). sf is known to have narrower leaflets and reduced vascular density, 24 and our rough mapping of the sf mutation identified a genomic location close to that known for the WOX1 locus (at the end of chromosome 3; Figure S4A).…”

“…Leaves of bip and sf double mutants are more complex than those of wox1 and narrower than those of bip3, confirming that SF promotes secondary leaflet formation, as suggested by previous studies. [21][22][23] Moreover, the double mutant showed low LVD. A recent study suggested that the regulation of local growth and differentiation in leaf primordia leads to diversity in leaf shape.…”

“…WOX1 is expressed in leaf primordia and is involved in leaf lamina expansion in various plant species, including tomato. [18][19][20][21][22][23] In the Medicago truncatula wox1 mutant, leaf vein density was lower than that in the wild type (WT). 19,23 Therefore, Sl WOX1 is likely to be a candidate gene for controlling both leaflet width and leaf vein density in the tomato.…”

In silico identification, characterization expression profile of WUSCHEL-Related Homeobox (WOX) gene family in two species of kiwifruit

“…However, WUS and WOX6 genes possess some similar functions and could be replaced mutually sometimes ( Dolzblasz et al, 2016 ). WOX1 and WOX3 has been demonstated redundantly control leaves development in Petunia, Arabidopsis and tomatos ( Vandenbussche et al, 2009 ; Nakata et al, 2018 ; Wang et al, 2021 ). WOX6 and WOX7 comprise close relatives of WOX1 and WOX5 , respectively, and are possibly due to the recent whole-genome duplication ( Blanc & Wolfe, 2004 ).…”

The Genetic Control of the Compound Leaf Patterning in Medicago truncatula

“…Formation of the leaf blade requires growth along the mediolateral axis, and WOX1 genes were found to be specifically involved in this process in diverse eudicot species ( Vandenbussche et al, 2009 ; Nakata et al, 2012 ; Zhuang et al, 2012 ; Vandenbussche, 2021 ; Wang C. et al, 2021 ). In A. thaliana , two WOX family genes, WUS-related HOMEOBOX1 ( WOX1 ) and PRESSED FLOWER ( PRS )/ WOX3 , are expressed at the middle domain between the adaxial and the abaxial domains at the P2 stage and the leaf margin at later stages.…”