Expression of barley HvCBF4 enhances tolerance to abiotic stress in transgenic rice.
C-repeat/dehydration-responsive element binding factors (CBF/DREBs) are a family of transcription factors that regulate freezing tolerance in Arabidopsis. As a step towards understanding the stress response of monocotyledonous plants, we isolated a barley gene HvCBF4 whose expression is induced by low-temperature stress. Transgenic over-expression of HvCBF4 in rice resulted in an increase in tolerance to drought, high-salinity and low-temperature stresses without stunting growth. Interestingly, under low-temperature conditions, the maximum photochemical efficiency of photosystem II in the dark-adapted state (F(v)/F(m), where F(v) is the variable fluorescence and F(m) is the maximum fluorescence) in HvCBF4 plants was higher by 20% and 10% than that in non-transgenic and CBF3/DREB1A plants, respectively. Using the 60K Rice Whole Genome microarray, 15 rice genes were identified that were activated by HvCBF4. When compared with 12 target rice genes of CBF3/DREB1A, five genes were common to both HvCBF4 and CBF3/DREB1A, and 10 and seven genes were specific to HvCBF4 and CBF3/DREB1A, respectively. Interestingly, HvCBF4 did not activate Dip1 and Lip5, two important target genes of CBF3/DREB1A, in transgenic rice under normal growth conditions, but their expression was enhanced by HvCBF4 under low-temperature conditions. Our results suggest that CBF/DREBs of barley act differently from those of Arabidopsis in transgenic rice.
Oh
Se-Jun
SJ
School of Biotechnology and Environmental Engineering, Myongji University, Yongin 449-728, South Korea.
Kwon
Chang-Woo
CW
Choi
Dong-Woog
DW
Song
Sang Ik
SI
Kim
Ju-Kon
JK
D000222:Adaptation, Physiological / Q000187:drug effects / Q000235:genetics / Q000502:physiology; D002734:Chlorophyll / Q000378:metabolism; D004190:Disasters; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D001467:Hordeum / Q000235:genetics*; D012275:Oryza / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics* / Q000502:physiology; D030821:Plants, Genetically Modified; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012965:Sodium Chloride / Q000494:pharmacology; D013696:Temperature; D015534:Trans-Activators / Q000235:genetics* / Q000502:physiology
D010940:Plant Proteins; D015534:Trans-Activators; D002734:Chlorophyll; D012965:Sodium Chloride