Ectopic expression of a phytochrome B gene from Chinese cabbage (Brassica rapa L. ssp. pekinensis) in Arabidopsis thaliana promotes seedling de-etiolation, dwarfing in mature plants, and delayed flowering.
Phytochrome B (phyB) is an essential red light receptor that predominantly mediates seedling de-etiolation, shade-avoidance response, and flowering time. In this study, we isolate a full-length cDNA of PHYB, designated BrPHYB, from Chinese cabbage (Brassica rapa L. ssp. pekinensis), and we find that BrphyB protein has high amino acid sequence similarity and the closest evolutionary relationship to Arabidopsis thaliana phyB (i.e., AtphyB). Quantitative reverse transcription (RT)-PCR results indicate that the BrPHYB gene is ubiquitously expressed in different tissues under all light conditions. Constitutive expression of the BrPHYB gene in A. thaliana significantly enhances seedling de-etiolation under red- and white-light conditions, and causes dwarf stature in mature plants. Unexpectedly, overexpression of BrPHYB in transgenic A. thaliana resulted in reduced expression of gibberellins biosynthesis genes and delayed flowering under short-day conditions, whereas AtPHYB overexpression caused enhanced expression of FLOWERING LOCUS T and earlier flowering. Our results suggest that BrphyB might play an important role in regulating the development of Chinese cabbage. BrphyB and AtphyB have conserved functions during de-etiolation and vegetative plant growth and divergent functions in the regulation of flowering time.
Beijing Radiation Center, Beijing, 100875, People's Republic of China.
Mei-Fang
MF
Song
Shu
S
Zhang
Pei
P
Hou
Hong-Zhong
HZ
Shang
Hai-Ke
HK
Gu
Jing-Juan
JJ
Li
Yang
Y
Xiao
Lin
L
Guo
Liang
L
Su
Jian-Wei
JW
Gao
Jian-Ping
JP
Yang
D017360:Arabidopsis / Q000235:genetics* / Q000254:growth & development / Q000528:radiation effects; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D001483:Base Sequence; D029741:Brassica rapa / Q000235:genetics*; D064527:Etiolation / Q000235:genetics*; D035264:Flowers / Q000235:genetics / Q000254:growth & development / Q000528:radiation effects; D015870:Gene Expression; D018507:Gene Expression Regulation, Developmental; D018506:Gene Expression Regulation, Plant; D005875:Gibberellins / Q000378:metabolism; D008027:Light; D008969:Molecular Sequence Data; D009928:Organ Specificity; D010802:Phylogeny; D051939:Phytochrome B / Q000235:genetics* / Q000378:metabolism; D010937:Plant Growth Regulators / Q000378:metabolism; D018515:Plant Leaves / Q000235:genetics / Q000254:growth & development / Q000528:radiation effects; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D030821:Plants, Genetically Modified; D036226:Seedlings / Q000235:genetics / Q000254:growth & development / Q000528:radiation effects; D017422:Sequence Analysis, DNA; D013997:Time Factors
D029681:Arabidopsis Proteins; D005875:Gibberellins; C497952:PHYB protein, Arabidopsis; D010937:Plant Growth Regulators; D010940:Plant Proteins; D051939:Phytochrome B