HD-ZIP I Transcription Factor (<i>PtHB13</i>) Negatively Regulates Citrus Flowering through Binding to <i>FLOWERING LOCUS C</i> Promoter
Yu-Jiao Ma,
Pei-Ting Li,
Lei-Ming Sun,
Huan Zhou,
Ren-Fang Zeng,
Xiao-Yan Ai,
Jin-Zhi Zhang,
Chun-Gen Hu
Affiliations
Yu-Jiao Ma
Key Laboratory of Horticultural Plant Biology (Ministry of Education), College of Horticulture and Forestry Science, Huazhong Agricultural University, Wuhan 430070, China
Pei-Ting Li
Key Laboratory of Horticultural Plant Biology (Ministry of Education), College of Horticulture and Forestry Science, Huazhong Agricultural University, Wuhan 430070, China
Lei-Ming Sun
Chinese Academy of Agriculture Sciences, Zhengzhou Fruit Research Institute, Zhengzhou 450009, China
Huan Zhou
Key Laboratory of Horticultural Plant Biology (Ministry of Education), College of Horticulture and Forestry Science, Huazhong Agricultural University, Wuhan 430070, China
Ren-Fang Zeng
Key Laboratory of Horticultural Plant Biology (Ministry of Education), College of Horticulture and Forestry Science, Huazhong Agricultural University, Wuhan 430070, China
Xiao-Yan Ai
Institute of Pomology and Tea, Hubei Academy of Agricultural Sciences, Wuhan 430070, China
Jin-Zhi Zhang
Key Laboratory of Horticultural Plant Biology (Ministry of Education), College of Horticulture and Forestry Science, Huazhong Agricultural University, Wuhan 430070, China
Chun-Gen Hu
Key Laboratory of Horticultural Plant Biology (Ministry of Education), College of Horticulture and Forestry Science, Huazhong Agricultural University, Wuhan 430070, China
For floral induction in adult citrus, low temperature is one of the most important environmental factors. FLOWERING LOCUS C (FLC) plays a very important role in low-temperature-induced Arabidopsis flowering by repressed FLC expression under exposure to prolonged low-temperature conditions. However, little is known about the FLC regulation mechanism in perennial woody plants such as citrus. In this study, the functions of citrus FLC homolog (PtFLC) were investigated by ectopic expression in Arabidopsis. Transcription factor of homeodomain leucine zipper I (HD-ZIP I) as an upstream regulator of PtFLC was identified by yeast one-hybrid screen to regulate its transcription. The HD-ZIP I transcription factor was highly homologous to Arabidopsis ATHB13 and thus was named PtHB13. Ectopically expressed PtHB13 inhibited flowering in transgenic Arabidopsis. Furthermore, the expression of PtFLC and PtHB13 showed a seasonal change during the floral induction period and was also affected by low temperature. Thus, we propose that PtHB13 binds to PtFLC promoter to regulate its activity during the citrus floral induction process.