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Transcription factor control of myrosin cell development in Arabidopsis.

University of British Columbia

Brassicaceae shoots harbor a glucosinolate-myrosinase system that acts as a chemically induced defense against insect predation and microorganisms. In Arabidopsis, myrosinase,also known as Thioglucoside Glucohydrolase (TGG), accumulates in the tonoplast of guard cells (GCs) as well as of myrosin phloem cells (MPCs). The basic-Helix-Loop-Helix (bHLH) transcription factor FAMA is essential for stomatal development, where it is strongly expressed just before and after the final division that generates the two-celled stoma. FAMA enforces guard cell fate and ensures that stomata contain just two guard cells, but no other function for FAMA has been demonstrated. I report that FAMA and a second guard cell fate marker are also expressed in shoots in developing and mature MPCs. MPCs were found to arise from the ground meristem, not the procambium, and thus are not part of the phloem. The loss of FAMA function abolishes MPCs and abrogates the expression of the myrosinase genes, TGG1 and TGG2. In addition, MPC development is regulated by auxin-related signaling. The loss of function of the GNOM gene as well as the chemical inhibition of auxin efflux, disrupt MPC patterning and morphogenesis. Thus FAMA confers MPC fate as well as the expression of myrosinase genes. In addition, polar auxin efflux is required for MPC development and patterning.

Text

2014-09-30

Attribution-NonCommercial-NoDerivs 2.5 Canada

http://hdl.handle.net/2429/45057

Botany

University of British Columbia

UBCV

http://creativecommons.org/licenses/by-nc-nd/2.5/ca/