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Article|07 Mar 2022|OPEN
Mobility of FLOWERING LOCUS T protein as a systemic signal in trifoliate orange and its low accumulation in grafted juvenile scions
Yan-Mei Wu1 ,† , Yu-Jiao Ma1 ,† , Min Wang, Huan Zhou1 , Zhi-Meng Gan1 , Ren-Fang Zeng1 , Li-Xia Ye1 , Jing-Jing Zhou1 , Jin-Zhi Zhang1 , and Chun-Gen Hu,1 ,
1Key Laboratory of Horticultural Plant Biology (Ministry of Education), College of Horticulture and Forestry Science, Huazhong Agricultural University, Wuhan 430070, China
*Corresponding author. E-mail: jinzhizhang@mail.hzau.edu.cn,chungen@mail.hzau.edu.cn
Both authors contributed equally to the study.

Horticulture Research 9,
Article number: uhac056 (2022)
doi: https://doi.org/10.1093/hr/uhac056
Views: 173

Received: 30 Nov 2021
Accepted: 21 Feb 2022
Published online: 07 Mar 2022

Abstract

The long juvenile period of perennial woody plants is a major constraint in breeding programs. FLOWERING LOCUS T (FT) protein is an important mobile florigen signal that induces plant flowering. However, whether FT can be transported in woody plants to shorten the juvenile period is unknown, and its transport mechanism remains unclear. In this study, trifoliate orange FT (ToFT) and Arabidopsis FT (AtFT, which has been confirmed to be transportable in Arabidopsis) as a control were transformed into tomato and trifoliate orange, and early flowering was induced in the transgenic plants. Long-distance and two-way (upward and downward) transmission of ToFT and AtFT proteins was confirmed in both tomato and trifoliate orange using grafting and western blot analysis. However, rootstocks of transgenic trifoliate orange could not induce flowering in grafted wild-type juvenile scions because of the low accumulation of total FT protein in the grafted scions. It was further confirmed that endogenous ToFT protein was reduced in trifoliate orange, and the accumulation of the transported ToFT and AtFT proteins was lower than that in grafted juvenile tomato scions. Furthermore, the trifoliate orange FT-INTERACTING PROTEIN1 homolog (ToFTIP1) was isolated by yeast two-hybrid analysis. The FTIP1 homolog may regulate FT transport by interacting with FT in tomato and trifoliate orange. Our findings suggest that FT transport may be conserved between the tomato model and woody plants. However, in woody plants, the transported FT protein did not accumulate in significant amounts in the grafted wild-type juvenile scions and induce the scions to flower.