Experimental validation of the mechanism of stomatal development diversification

Abstract

Stomata are the structures responsible for gas exchange in plants. The established framework for stomatal development is based on the model plant Arabidopsis, but diverse patterns of stomatal development have been observed in other plant lineages and species. The molecular mechanisms behind these diversified patterns are still poorly understood. We recently proposed a model for the molecular mechanisms of the diversification of stomatal development based on the genus Callitriche (Plantaginaceae), according to which a temporal shift in the expression of key stomatal transcription factors SPEECHLESS and MUTE leads to changes in the behavior of meristemoids (stomatal precursor cells). In the present study, we genetically manipulated Arabidopsis to test this model. By altering the timing of MUTE expression, we successfully generated Arabidopsis plants with early differentiation or prolonged divisions of meristemoids, as predicted by the model. The epidermal morphology of the generated lines resembled that of species with prolonged or no meristemoid divisions. Thus, the evolutionary process can be reproduced by varying the SPEECHLESS to MUTE transition. We also observed unexpected phenotypes, which indicated the participation of additional factors in the evolution of the patterns observed in nature. This study provides novel experimental insights into the diversification of meristemoid behaviors.

A history-dependent integrase recorder of plant gene expression with single cell resolution

“…It has been shown that the timing between SPCH and MUTE expression differs between the development of two types of stomata: anisocytic (A) and nonanisocytic (NA) 51 . During stomatal differentiation, SPCH initiates and MUTE terminates the asymmetrical divisions of the meristemoid 49 .…”

Beyond stomatal development: SMF transcription factors as versatile toolkits for land plant evolution

“…In seed plants, FAMA regulates the formation of myrosin cells, Brassicales-specific idioblasts (Li & Sack, 2014; Shirakawa et al, 2014), which provides another example of SMF co-option. We recently identified the interspecific differences in the spatiotemporal patterns of SPCH and MUTE expression underlying the diversification of stomatal development patterns in the genus Callitriche (Plantaginacea) (Doll et al, 2021a, 2021b, 2023). This shows that SMFs also play a pivotal role in evolution at the species level.…”