AUTHOR=Luján María A. , Soria-García Ángel , Claver Ana , Lorente Patricia , Rubio María C. , Picorel Rafael , Alfonso Miguel 

TITLE=Different Cis-Regulatory Elements Control the Tissue-Specific Contribution of Plastid ω-3 Desaturases to Wounding and Hormone Responses

JOURNAL=Frontiers in Plant Science

VOLUME=12

YEAR=2021

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2021.727292

DOI=10.3389/fpls.2021.727292

ISSN=1664-462X

ABSTRACT=<p>Trienoic fatty acids are essential constituents of biomembranes and precursors of jasmonates involved in plant defense responses. Two ω-3 desaturases, <italic>At</italic>FAD7 and <italic>At</italic>FAD8, synthetize trienoic fatty acids in the plastid. Promoter:GUS and mutagenesis analysis was used to identify <italic>cis</italic>-elements controlling <italic>AtFAD7</italic> and <italic>AtFAD8</italic> basal expression and their response to hormones or wounding. <italic>AtFAD7</italic> promoter GUS activity was much higher than that of <italic>AtFAD8</italic> in leaves, with specific <italic>AtFAD7</italic> expression in the flower stamen and pistil and root meristem and vasculature. This specific tissue and organ expression of <italic>AtFAD7</italic> was controlled by different <italic>cis</italic>-elements. Thus, promoter deletion and mutagenesis analysis indicated that WRKY proteins might be essential for basal expression of <italic>AtFAD7</italic> in leaves. Two MYB target sequences present in the <italic>AtFAD7</italic> promoter might be responsible for its expression in the flower stamen and stigma of the pistil and in the root meristem, and for the <italic>AtFAD7</italic> wound-specific response. Two MYB target sequences detected in the distal region of the <italic>AtFAD8</italic> gene promoter seemed to negatively control <italic>AtFAD8</italic> expression, particularly in true leaves and flowers, suggesting that MYB transcription factors act as repressors of <italic>AtFAD8</italic> gene basal expression, modulating the different relative abundance of both plastid ω-3 desaturases at the transcriptional level. Our data showed that the two ABA repression sequences detected in the <italic>AtFAD7</italic> promoter were functional, suggesting an ABA-dependent mechanism involved in the different regulation of both ω-3 plastid desaturases. These results reveal the implication of different signaling pathways for the concerted regulation of trienoic fatty acid content in Arabidopsis.</p>