Non-specific phytohormonal induction of AtMYB44 and suppression of jasmonate-responsive gene activation in Arabidopsis thaliana.
The Arabidopsis thaliana transcription factor gene AtMYB44 was induced within 10 min by treatment with methyl jasmonate (MeJA). Wound-induced expression of the gene was observed in local leaves, but not in distal leaves, illustrating jasmonate-independent induction at wound sites. AtMYB44 expression was not abolished in Arabidopsis mutants insensitive to jasmonate (coi1), ethylene (etr1), or abscisic acid (abi3-1) when treated with the corresponding hormones. Moreover, various growth hormones and sugars also induced rapid AtMYB44 transcript accumulation. Thus, AtMYB44 gene activation appears to not be induced by any specific hormone. MeJA-induced activation of jasmonate-responsive genes such as JR2, VSP, LOXII, and AOS was attenuated in transgenic Arabidopsis plants overexpressing the gene (35S:AtMYB44), but significantly enhanced in atmyb44 knockout mutants. The 35S:MYB44 and atmyb44 plants did not show defectiveness in MeJA-induced primary root growth inhibition, indicating that the differences in jasmonate-responsive gene expression observed was not due to alterations in the jasmonate signaling pathway. 35S:AtMYB44 seedlings exhibited slightly elevated chlorophyll levels and less jasmonate- induced anthocyanin accumulation, demonstrating suppression of jasmonate-mediated responses and enhancement of ABA-mediated responses. These observations support the hypothesis of mutual antagonistic actions between jasmonate- and abscisic acid-mediated signaling pathways.
Jung
Choonkyun
C
Department of Agricultural Biotechnology and Center for Agricultural Biomaterials, Seoul National University, Seoul, 151-921, Korea.
Shim
Jae Sung
JS
Seo
Jun Sung
JS
Lee
Han Yong
HY
Kim
Chung Ho
CH
Choi
Yang Do
YD
Cheong
Jong-Joo
JJ
D000040:Abscisic Acid / Q000378:metabolism*; D000085:Acetates / Q000378:metabolism*; D000872:Anthocyanins / Q000378:metabolism; D017360:Arabidopsis / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000096:biosynthesis* / Q000235:genetics; D002734:Chlorophyll / Q000378:metabolism; D003517:Cyclopentanes / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000096:biosynthesis / Q000235:genetics; D005030:Ethylenes / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D016313:Genes, abl / Q000235:genetics; D054883:Oxylipins / Q000378:metabolism*; D010937:Plant Growth Regulators / Q000378:metabolism*; D030821:Plants, Genetically Modified; D011956:Receptors, Cell Surface / Q000096:biosynthesis / Q000235:genetics; D015398:Signal Transduction; D014157:Transcription Factors / Q000096:biosynthesis* / Q000235:genetics; D015533:Transcriptional Activation
D000085:Acetates; D000872:Anthocyanins; D029681:Arabidopsis Proteins; C092776:CONSTANS protein, Arabidopsis; D003517:Cyclopentanes; D004268:DNA-Binding Proteins; C494590:ETR1 protein, Arabidopsis; D005030:Ethylenes; C529221:At5g67300 protein, Arabidopsis; D054883:Oxylipins; D010937:Plant Growth Regulators; D011956:Receptors, Cell Surface; D014157:Transcription Factors; D002734:Chlorophyll; D000040:Abscisic Acid; C072239:methyl jasmonate; C036216:ethylene