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Original Research ARTICLE Provisionally accepted The full-text will be published soon. Notify me

Front. Plant Sci. | doi: 10.3389/fpls.2019.01300

The tomato genome encodes SPCH, MUTE and FAMA candidates that can replace the endogenous functions of their Arabidopsis orthologues

  • 1Departamento de Ciencias Ambientales, Universidad de Castilla-La Mancha, Spain
  • 208349, Semillas Fitó S.A., Spain

Stomatal abundance determines the maximum potential for gas exchange between the plant and the atmosphere. In Arabidopsis, it is set during organ development through complex genetic networks linking epidermal differentiation programs with environmental response circuits. Three related bHLH transcription factors, SPCH, MUTE and FAMA, act as positive drivers of stomata differentiation. Mutant alleles of some of these genes sustain different stomatal numbers in the mature organs and have potential to modify plant performance under different environmental conditions. However, knowledge about stomatal genes in dicotyledoneous crops is scarce. In this work, we identified the Solanum lycopersicum putative orthologues of these three master regulators and assessed their functional orthology by their ability to complement Arabidopsis loss-of-function mutants, the epidermal phenotypes elicited by their conditional overexpression, and the expression patterns of their promoter regions in Arabidopsis. Our results indicate that the tomato proteins are functionally equivalent to their Arabidopsis counterparts and that the tomato putative promoter regions display temporal and spatial expression domains similar to those reported for the Arabidopsis genes. In vivo tracking of tomato stomatal lineages in developing cotyledons revealed cell division and differentiation histories similar to those of Arabidopsis. Interestingly, the Solanum lycopersicum genome harbors a FAMA-like gene, expressed in leaves but functionally distinct from the true FAMA orthologue. Thus, the basic program for stomatal development in Solanum lycopersicum uses key conserved genetic determinants. This opens the possibility of modifying stomatal abundance in tomato through previously tested Arabidopsis alleles conferring altered stomata abundance phenotypes that correlate with physiological traits related to water status, leaf cooling or photosynthesis.

Keywords: Stomatal development, tomato (Solanum lycopersicum), Arabidopsis, Orthologous genes, SPCH, MUTE, FAMA

Received: 10 May 2019; Accepted: 18 Sep 2019.

Copyright: © 2019 Ortega, De Marcos, Illescas, Mena and Fenoll. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence:
Prof. Montaña Mena, Departamento de Ciencias Ambientales, Universidad de Castilla-La Mancha, Toledo, 45071, Spain, montana.mena@uclm.es
Prof. Carmen Fenoll, Departamento de Ciencias Ambientales, Universidad de Castilla-La Mancha, Toledo, 45071, Spain, carmen.fenoll@uclm.es