Importantly, expression of MYB21 and other transcription factors required for stamen and pollen maturation was strongly reduced in stamens of MYC5‐SRDX plants relative to the wild type. In particular, MYC5‐SRDX plants were male‐sterile, with defects in stamen filament elongation, anther dehiscence and pollen viability. Two allelic myc5 mutants exhibited no overt phenotype however, transgenic lines expressing MYC5 fused to an SRDX (SUPERMAN repressive domain X) motif phenocopied mutants defective in JA signaling. A G‐box sequence in the JAZ2 promoter was necessary and sufficient for induction by MYC5 (as it is for MYC2, MYC3 and MYC4), and induction of JAZ genes was repressed by co‐expression of a stabilized, JAZ1ΔJas repressor. We found that a closely related transcription factor, MYC5 (bHLH28), was able to induce JAZ promoters that control some of the early JA‐responsive genes in a Daucus carota (carrot) protoplast expression system. MYC2, MYC3 and MYC4 are JAZ‐interacting bHLH transcription factors that play a major role in controlling JA responses in vegetative tissue, but are not likely to play a role in reproductive tissue. Arabidopsis thaliana plants deficient in JA‐biosynthesis or ‐signaling are male‐sterile, with defects in stamen and pollen development. 849-860 ISSN: 0960-7412 Subject: Arabidopsis thaliana, basic helix-loop-helix transcription factors, genetically modified organisms, protoplasts, viability, phenotype, jasmonic acid, Daucus carota, chimerism, dehiscence, genes, male fertility, mutants, carrots, pollen Abstract: Jasmonate hormone (JA) plays critical roles in both plant defense and reproductive development. Male sterility in Arabidopsis induced by overexpression of a MYC5SRDX chimeric repressor Male sterility in Arabidopsis induced by overexpression of a MYC5SRDX chimeric repressor Figueroa, Pablo Browse, John 00:00:00 Jasmonate hormone (JA) plays critical roles in both plant defense and reproductive development. Male sterility in Arabidopsis induced by overexpression of a MYC5‐SRDX chimeric repressor Author: Pablo Figueroa, John Browse Source: plant journal 2015 v.81 no.6 pp. Transcription factors (TFs) fused to the SRDX (a modified repressor domain at the C-terminal region of Arabidopsis SUPERMAN (SUPRD) with the sequence of LDLDLELRLGFA) motif repression domain at their C terminus, generating a chimeric repressor, could act as a dominant suppressor and overcome problems related to functional redundancy between TFs.
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