Role of Arabidopsis RAP2.4 in regulating light- and ethylene-mediated developmental processes and drought stress tolerance.
Light and the plant hormone ethylene regulate many aspects of plant growth and development in an overlapping and interdependent fashion. Little is known regarding how their signal transduction pathways cross-talk to regulate plant development in a coordinated manner. Here, we report functional characterization of an AP2/DREB-type transcription factor, Arabidopsis RAP2.4, in mediating light and ethylene signaling. Expression of the RAP2.4 gene is down-regulated by light but up-regulated by salt and drought stresses. RAP2.4 protein is constitutively targeted to the nucleus and it can bind to both the ethylene-responsive GCC-box and the dehydration-responsive element (DRE). We show that RAP2.4 protein possesses an intrinsic transcriptional activation activity in yeast cells and that it can activate a reporter gene driven by the DRE cis-element in Arabidopsis protoplasts. Overexpression of RAP2.4 or mutation in RAP2.4 cause altered expression of representative light-, ethylene-, and drought-responsive genes. Although no salient phenotype was observed with a rap2.4 loss-of-function mutant, constitutive overexpression of RAP2.4 results in defects in multiple developmental processes regulated by light and ethylene, including hypocotyl elongation and gravitropism, apical hook formation and cotyledon expansion, flowering time, root elongation, root hair formation, and drought tolerance. Based on these observations, we propose that RAP2.4 acts at or downstream of a converging point of light and ethylene signaling pathways to coordinately regulate multiple developmental processes and stress responses.
Lin
Rong-Cheng
RC
Boyce Thompson Institute for Plant Research, Cornell University, Ithaca, NY 14853, USA.
Park
Hee-Jin
HJ
Wang
Hai-Yang
HY
D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics* / Q000254:growth & development / Q000528:radiation effects; D029681:Arabidopsis Proteins / Q000187:drug effects / Q000378:metabolism / Q000528:radiation effects; D005030:Ethylenes / Q000494:pharmacology*; D017343:Genes, Plant / Q000187:drug effects / Q000528:radiation effects*; D008027:Light; D010937:Plant Growth Regulators / Q000494:pharmacology*; D018749:RNA, Plant / Q000187:drug effects / Q000235:genetics / Q000528:radiation effects; D012337:RNA, Ribosomal, 18S / Q000187:drug effects / Q000235:genetics / Q000528:radiation effects; D011993:Recombinant Fusion Proteins / Q000187:drug effects / Q000378:metabolism / Q000528:radiation effects; D036226:Seedlings / Q000187:drug effects / Q000235:genetics / Q000528:radiation effects; D012965:Sodium Chloride / Q000494:pharmacology; D020668:rap GTP-Binding Proteins / Q000187:drug effects / Q000378:metabolism* / Q000528:radiation effects
D029681:Arabidopsis Proteins; D005030:Ethylenes; D010937:Plant Growth Regulators; D018749:RNA, Plant; D012337:RNA, Ribosomal, 18S; D011993:Recombinant Fusion Proteins; D012965:Sodium Chloride; C036216:ethylene; D020668:rap GTP-Binding Proteins