The auxin receptor TIR1 homolog (PagFBL1) regulates adventitious rooting through interactions with Aux/IAA28 in Populus

First author: Wenbo Shu; Affiliations: Research Institute of Forestry, Chinese Academy of Forestry (中国林科学院林业研究所): Beijing, China

Corresponding author: Meng‐hu Lu (卢孟柱)

Adventitious roots (不定根) occur naturally in many species, and can also be induced from explants (外植体) of some tree species including Populus, providing an important means of clonal propagation. Auxin has been identified as playing a crucial role in adventitious root formation, but the associated molecular regulatory mechanisms need to be elucidated. In this study, we examined the role of PagFBL1, the hybrid poplar (Populus alba × P. glandulosaclone 84K) homolog of Arabidopsis auxin receptor TIR1, in adventitious root formation in poplar. Similar to the distribution pattern of auxin during initiation of adventitious roots, PagFBL1 expression was concentrated in the cambium and secondary phloem in stems during adventitious root induction and initiation phases, but decreased in emerging adventitious root primordia (原基). Overexpressing PagFBL1 stimulated adventitious root formation and increased root biomass, while knockdown of PagFBL1 transcript levels delayed adventitious root formation and decreased root biomass. Transcriptome analyses of PagFBL1 overexpressing lines indicated that an extensive remodeling of gene expression was stimulated by auxin signaling pathway during early adventitious root formation. In addition, PagIAA28 was identified as downstream targets of PagFBL1. We propose that the PagFBL1‐PagIAA28 module promotes adventitious rooting, and could be targeted to improve Populus propagation by cuttings (扦插).

许多物种都能形成不定根，像杨树等一些林木甚至能够从外植体诱导出不定根，这是一个无性繁殖的重要方式。以往的研究已经证明生长素在不定根的形成过程中发挥至关重要的作用，但相关的分子调控机制还需要进一步的阐明。本文研究了拟南芥生长素受体TIR1在杂交杨中的同源基因PagFBL1在杨树不定根形成过程中的作用。与生长素在不定根起始时的分布模式相同，PagFBL1基因的表达在不定根诱导和起始阶段在茎的形成层和次生韧皮部富集，而在正在形成的不定根原基中降低。过表达PagFBL1基因能够刺激不定根的形成，并增加根的生物量，而敲低PagFBL1基因的表达则会延迟不定根的形成，并减少根的生物量。对PagFBL1基因过表达株系的转录组分析显示在不定根形成早期存在广泛的受生长素信号通路刺激的基因表达重塑。另外，PagIAA28基因被鉴定为PagFBL1蛋白的下游靶基因。作者提出PagFBL1‐PagIAA28调控模块促进不定根的形成，可以用来提高杨树扦插繁殖的成功率。

通讯：卢孟柱 (http://skltgb.caf.ac.cn/content/yanjiuduiwu/zhuanjiafengcai/201306u84.shtml)

个人简介：1987年毕业于北京农业大学生物学院微生物专业，获学士学位；1990年毕业于北京农业大学生物学院，获硕士学位，研究方向为植物基因工程；1997年毕业于瑞典农业大学森林遗传与植物生理系，获博士学位，研究方向为林木分子遗传。

研究方向：树木分子生物学。

doi: https://doi.org/10.1111/pbi.12980

Journal: Plant Biotechnology Journal

First Published: 27 June, 2018

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