Retrotransposon-mediated DELLA transcriptional reprograming underlies semi-dominant dwarfism in foxtail millet  

作　　者：Meicheng Zhao Hui Zhi Xue Zhang Guanqing Jia Xianmin Diao 

机构地区：[1]Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Beijing 100081, China [2]Center for Agricultural Research Resources, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Shijiazhuang 050021, Hebei, China

出　　处：《The Crop Journal》2019年第4期458-468,共11页作物学报（英文版）

基　　金：supported by the National Natural Science Foundation of China (31871634, 31500985)

摘　　要：Retrotransposons account for a large proportion of the genome and genomic variation, and play key roles in creating novel genes and diversifying the genome in many eukaryotic species. Although retrotransposons are abundant in plants, their roles had been underestimated because of a lack of research. Here, we characterized a gibberellin Acid (GA)-insensitive dwarf mutant, 84133, in foxtail millet. Map-based cloning revealed a 5.5-kb Copia-like retrotransposon insertion in DWARF1 (D1), which encodes a DELLA protein. Transcriptional analysis showed that the Copia retrotransposon mediated the transcriptional reprogramming of D1 leading to a novel N-terminal-deleted truncated DELLA transcript that was putatively driven by Copia's LTR, namely D1-TT, and another chimeric transcript. The presence of D1-TT was confirmed by protein immunodetection analysis. Furthermore, D1-TT protein was resistant to GA3 treatment compared with the intact DELLA protein due to its inability to interact with the GA receptor, SiGID1. Overexpression of D1-TT in foxtail millet resulted in dwarf plants, confirming that it determines the dwarfism of 84133. Thus, our study documents a rare instance of long terminal repeat (LTR) retrotransposon-mediated transcriptional reprograming in the plant kingdom. These results shed light on the function of LTR retrotransposons in generating new gene functions and genetic diversity.Retrotransposons account for a large proportion of the genome and genomic variation, and play key roles in creating novel genes and diversifying the genome in many eukaryotic species.Although retrotransposons are abundant in plants, their roles had been underestimated because of a lack of research. Here, we characterized a gibberellin Acid(GA)-insensitive dwarf mutant, 84133, in foxtail millet. Map-based cloning revealed a 5.5-kb Copia-like retrotransposon insertion in DWARF1(D1), which encodes a DELLA protein. Transcriptional analysis showed that the Copia retrotransposon mediated the transcriptional reprogramming of D1 leading to a novel N-terminal-deleted truncated DELLA transcript that was putatively driven by Copia’s LTR, namely D1-TT, and another chimeric transcript. The presence of D1-TT was confirmed by protein immunodetection analysis. Furthermore, D1-TT protein was resistant to GA3 treatment compared with the intact DELLA protein due to its inability to interact with the GA receptor, SiGID1. Overexpression of D1-TT in foxtail millet resulted in dwarf plants, confirming that it determines the dwarfism of 84133. Thus, our study documents a rare instance of long terminal repeat(LTR) retrotransposon-mediated transcriptional reprograming in the plant kingdom. These results shed light on the function of LTR retrotransposons in generating new gene functions and genetic diversity.

关 键 词：RETROTRANSPOSON TRANSCRIPTIONAL reprogramming DELLA Dwarf breeding Foxtail millet (Setaria italica) 

分 类 号：S[农业科学]