OsARF16 is involved in cytokinin-mediated inhibition of phosphate transport and phosphate signaling in rice (Oryza sativa L.).
BACKGROUND
Plant responses to phytohormone stimuli are the most important biological features for plants to survive in a complex environment. Cytokinin regulates growth and nutrient homeostasis, such as the phosphate (Pi) starvation response and Pi uptake in plants. However, the mechanisms underlying how cytokinin participates in Pi uptake and Pi signaling are largely unknown. In this study, we found that OsARF16 is required for the cytokinin response and is involved in the negative regulation of Pi uptake and Pi signaling by cytokinin.


RESULTS
The mutant osarf16 showed an obvious resistance to exogenous cytokinin treatment and the expression level of the OsARF16 gene was considerably up-regulated by cytokinin. Cytokinin (6-BA) application suppressed Pi uptake and the Pi starvation response in wild-type Nipponbare (NIP) and all these responses were compromised in the osarf16 mutant. Our data showed that cytokinin inhibits the transport of Pi from the roots to the shoots and that OsARF16 is involved in this process. The Pi content in the osarf16 mutant was much higher than in NIP under 6-BA treatment. The expressions of PHOSPHATE TRANSPORTER1 (PHT1) genes, phosphate (Pi) starvation-induced (PSI) genes and purple PAPase genes were higher in the osarf16 mutant than in NIP under cytokinin treatment.


CONCLUSIONS
Our results revealed a new biological function for OsARF16 in the cytokinin-mediated inhibition of Pi uptake and Pi signaling in rice.
College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou 310036, China.
Chenjia
C
Shen
Henan Academy of Agricultural Sciences, Zhengzhou 450002, China.
Runqing
R
Yue
College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou 310036, China.
Yanjun
Y
Yang
Department of Plant Pathology, Washington State University, Pullman, WA 99164-6430, United States of America.
Lei
L
Zhang
College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou 310036, China.
Tao
T
Sun
Henan Academy of Agricultural Sciences, Zhengzhou 450002, China.
Shuanggui
S
Tie
College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou 310036, China.
Huizhong
H
Wang
D001692:Biological Transport; D003583:Cytokinins / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant; D009154:Mutation; D012275:Oryza / Q000235:genetics / Q000378:metabolism*; D010710:Phosphates / Q000378:metabolism*; D010758:Phosphorus / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D018517:Plant Roots / Q000378:metabolism; D018520:Plant Shoots / Q000235:genetics / Q000378:metabolism; D030821:Plants, Genetically Modified; D036226:Seedlings / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction / Q000235:genetics
D003583:Cytokinins; D010710:Phosphates; D010940:Plant Proteins; D010758:Phosphorus