OsBBX14 delays heading date by repressing florigen gene expression under long and short-day conditions in rice.
B-box (BBX) proteins are zinc finger proteins containing B-box domains, which have roles in Arabidopsis growth and development. However, little is known concerning rice BBXs. Herein, we identified a rice BBX protein, Oryza sativa BBX14 (OsBBX14). OsBBX14 is highly expressed in flag leaf blades. OsBBX14 expression shows a diurnal rhythm under photoperiodic conditions and subsequent continuous white light. OsBBX14 is located in the nucleus and has transcriptional activation potential. OsBBX14-overexpression (OsBBX14-OX) lines exhibited delayed heading date under long-day (LD) and short-day (SD) conditions, whereas RNAi lines of OsBBX14 lines had similar heading dates to the WT. The florigen genes, Hd3a and RFT1, were downregulated in the OsBBX14-OX lines under LD and SD conditions. Under LD conditions, Hd1 was expressed higher in the OsBBX14-OX lines than in the wild type (WT), and the rhythmic expression of circadian clock genes, OsLHY and OsPRR1, was changed in OsBBX14-OX lines. Thus, OsBBX14 acts as a floral repressor by promoting Hd1 expression under LD conditions, probably because of crosstalk with the circadian clock. Under SD conditions, Ehd1 expression was reduced in OsBBX14-OX lines, but Hd1 and circadian clock gene expressions were unaffected, indicating that OsBBX14 acts as a repressor of Ehd1. Our findings suggested that OsBBX14 regulates heading date differently under LD and SD conditions.
Shandong Rice Research Institute, Shandong Academy of Agricultural Sciences, Jinan 250100, PR China. Electronic address: baibosdau@163.com.
Bo
B
Bai
Shandong Rice Research Institute, Shandong Academy of Agricultural Sciences, Jinan 250100, PR China. Electronic address: zhaojie628@126.com.
Jie
J
Zhao
Shandong Rice Research Institute, Shandong Academy of Agricultural Sciences, Jinan 250100, PR China; College of Life Science, Shandong Normal University, Jinan 250014, PR China. Electronic address: lyp8908@126.com.
Yaping
Y
Li
Institute of Genetics and Developmental Biology, the Chinese Academy of Sciences, Beijing 100190, PR China. Electronic address: fangzhang@genetics.ac.cn.
Fang
F
Zhang
Shandong Rice Research Institute, Shandong Academy of Agricultural Sciences, Jinan 250100, PR China. Electronic address: zhousdrice@163.com.
Jinjun
J
Zhou
Institute of Genetics and Developmental Biology, the Chinese Academy of Sciences, Beijing 100190, PR China. Electronic address: fchen@genetics.ac.cn.
Fan
F
Chen
Shandong Rice Research Institute, Shandong Academy of Agricultural Sciences, Jinan 250100, PR China. Electronic address: xzhxie2010@163.com.
Xianzhi
X
Xie
D057906:Circadian Clocks; D002940:Circadian Rhythm; D015536:Down-Regulation; D060405:Florigen / Q000378:metabolism*; D035264:Flowers / Q000235:genetics / Q000502:physiology / Q000528:radiation effects; D015870:Gene Expression; D018506:Gene Expression Regulation, Plant; D017930:Genes, Reporter; D008027:Light; D012275:Oryza / Q000235:genetics* / Q000502:physiology / Q000528:radiation effects; D017440:Photoperiod; D010937:Plant Growth Regulators / Q000378:metabolism*; D018515:Plant Leaves / Q000235:genetics / Q000502:physiology / Q000528:radiation effects; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D015854:Up-Regulation; D016335:Zinc Fingers
D060405:Florigen; D010937:Plant Growth Regulators; D010940:Plant Proteins; D014157:Transcription Factors
B-box zinc finger protein; Circadian clock; Heading date; Photoperiod pathway; Rice