Arabidopsis thaliana SHOOT MERISTEMLESS Substitutes for Medicago truncatula SINGLE LEAFLET1 to Form Complex Leaves and Petals

Véronique Pautot (1) , Ana Berbel (2) , Thibaud Cayla (1) , Alexis Eschstruth (3) , Bernard Adroher , Pascal Ratet (3) , Francisco Madueño (1) , Patrick Laufs (1)

1 IJPB - Institut Jean-Pierre Bourgin
2 Universitad Politecnica de Valencia
3 IPS2 (UMR_9213 / UMR_1403) - Institut des Sciences des Plantes de Paris-Saclay

LEAFY plant-specific transcription factors, which are key regulators of flower meristem identity and floral patterning, also contribute to meristem activity. Notably, in some legumes, LFY orthologs such as Medicago truncatula SINGLE LEAFLET (SGL1) are essential in maintaining an undifferentiated and proliferating fate required for leaflet formation. This function contrasts with most other species, in which leaf dissection depends on the reactivation of KNOTTED-like class I homeobox genes (KNOXI). KNOXI and SGL1 genes appear to induce leaf complexity through conserved downstream genes such as the meristematic and boundary CUP-SHAPED COTYLEDON genes. Here, we compare in M. truncatula the function of SGL1 with that of the Arabidopsis thaliana KNOXI gene, SHOOT MERISTEMLESS (AtSTM). Our data show that AtSTM can substitute for SGL1 to form complex leaves when ectopically expressed in M. truncatula. The shared function between AtSTM and SGL1 extended to the major contribution of SGL1 during floral development as ectopic AtSTM expression could promote floral organ identity gene expression in sgl1 flowers and restore sepal shape and petal formation. Together, our work reveals a function for AtSTM in floral organ identity and a higher level of interchangeability between meristematic and floral identity functions for the AtSTM and SGL1 transcription factors than previously thought.

Mots clés: Medicago truncatula meristematic activity flower development SINGLE LEAFLET/LEAFY SHOOT MERISTEMLESS transcription factors; Medicago truncatula; meristematic activity; flower development; SINGLE LEAFLET/LEAFY; SHOOT MERISTEMLESS transcription factors; Medicago truncatula meristematic activity flower development SINGLE LEAFLET/LEAFY SHOOT MERISTEMLESS transcription factors

Domaines: Sciences du Vivant [q-bio]

Véronique Pautot, Ana Berbel, Thibaud Cayla, Alexis Eschstruth, Bernard Adroher, et al.. Arabidopsis thaliana SHOOT MERISTEMLESS Substitutes for Medicago truncatula SINGLE LEAFLET1 to Form Complex Leaves and Petals. International Journal of Molecular Sciences, 2022, 23, ⟨10.3390/ijms232214114⟩. ⟨hal-03875926⟩