Functional characterization of four APETALA2-family genes (RAP2.6, RAP2.6L, DREB19 and DREB26) in Arabidopsis.
APETALA2 (AP2) transcription factors (TFs) play very important roles in plant growth and development and in defense response. Here, we report functional characterization of four AP2 TF family genes [(RAP2.6 (At1g43160), RAP2.6L (At5g13330), DREB 26 (At1g21910) and DREB19 (At2g38340)] that were identified among NaCl inducible transcripts in abscisic acid responsive 17 (ABR17) transgenic Arabidopsis in our previous microarray analyses. DREB19 and DREB26 function as transactivators and localize in the nucleus. All four genes were abundant in early vegetative and flowering stages, although the magnitude of the expression varied. We observed tissue specific expression patterns for RAP2.6, RAP2.6L, DREB19 and DREB26 in flowers and other organs. RAP2.6 and RAP2.6L were responsive to stress hormones like jasmonic acid, salicylic acid, abscisic acid and ethylene in addition to salt and drought. DREB19 and DREB26 were less responsive to stress hormones, but the former was highly responsive to salt, heat and drought. Overexpression of RAP2.6 in Arabidopsis resulted in a dwarf phenotype with extensive secondary branching and small siliques, and DREB26 overexpression resulted in deformed plants. However, overexpression of RAP2.6L and DREB19 enhanced performance under salt and drought stresses without affecting phenotype. In summary, we have demonstrated that RAP2.6, RAP2.6L, DREB26 and DREB19 are transactivators, they exhibit tissue specific expression, and they participate in plant developmental processes as well as biotic and/or abiotic stress signaling. It is possible that the results from this study on these transcription factors, in particular RAP2.6L and DREB19, can be utilized in developing salt and drought tolerant plants in the future.
Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, AB, T6G 2P5, Canada.
Sowmya
S
Krishnaswamy
Shiv
S
Verma
Muhammad H
MH
Rahman
Nat N V
NN
Kav
D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics* / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D002467:Cell Nucleus / Q000378:metabolism; D003080:Cold Temperature; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D005966:Glucuronidase / Q000235:genetics / Q000378:metabolism; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D018398:Homeodomain Proteins / Q000235:genetics* / Q000378:metabolism; D006358:Hot Temperature; D018613:Microscopy, Confocal; D008856:Microscopy, Fluorescence; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000235:genetics* / Q000378:metabolism; D030821:Plants, Genetically Modified; D011401:Promoter Regions, Genetic / Q000235:genetics; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017386:Sequence Homology, Amino Acid; D012965:Sodium Chloride / Q000494:pharmacology; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D015533:Transcriptional Activation
C499534:APETALA2 protein, Arabidopsis; D029681:Arabidopsis Proteins; C555643:DREB19 protein, Arabidopsis; C555642:DREB26 protein, Arabidopsis; D018398:Homeodomain Proteins; D009687:Nuclear Proteins; C549102:RAP2.6 protein, Arabidopsis; C555644:RAP2.6L protein, Arabidopsis; D011993:Recombinant Fusion Proteins; D015534:Trans-Activators; D014157:Transcription Factors; D049452:Green Fluorescent Proteins; D012965:Sodium Chloride; D005966:Glucuronidase