Genome-wide identification of polar auxin transporter gene families reveals a possible new polar auxin flow in inverted cuttings of Populus yunnanensis

An-Pei Zhou; Yuan-Yuan Zhong; Si-Qi Li; Xuan Fei; Pei-Hua Gan; Dan Zong; Cheng-Zhong He

doi:10.1016/j.gene.2020.145349

Genome-wide identification of polar auxin transporter gene families reveals a possible new polar auxin flow in inverted cuttings of Populus yunnanensis

Gene. 2021 Mar 10:772:145349. doi: 10.1016/j.gene.2020.145349. Epub 2020 Dec 15.

Authors

An-Pei Zhou¹, Yuan-Yuan Zhong², Si-Qi Li², Xuan Fei², Pei-Hua Gan², Dan Zong², Cheng-Zhong He³

Affiliations

¹ Key Laboratory for Forest Genetic and Tree Improvement and Propagation in Universities of Yunnan Province, Southwest Forestry University, Kunming 650224, China; Institute of Jiangxi Oil-tea Camellia, Jiujiang University, Jiujiang 332005, China. Electronic address: 6090078@jju.edu.cn.
² Key Laboratory for Forest Genetic and Tree Improvement and Propagation in Universities of Yunnan Province, Southwest Forestry University, Kunming 650224, China; Key Laboratory of Biodiversity Conservation in Southwest China, State Forestry Administration, Southwest Forestry University, Kunming 650224, China.
³ Key Laboratory for Forest Genetic and Tree Improvement and Propagation in Universities of Yunnan Province, Southwest Forestry University, Kunming 650224, China; Key Laboratory of Biodiversity Conservation in Southwest China, State Forestry Administration, Southwest Forestry University, Kunming 650224, China; Key Laboratory for Forest Resources Conservation and Utilization in the Southwest Mountains of China, Ministry of Education, Southwest Forestry University, Kunming 650224, China. Electronic address: hecz@swfu.edu.cn.

PMID: 33338511
DOI: 10.1016/j.gene.2020.145349

Abstract

Inverted cuttings of Populus yunnanensis are characterized by enlarged stems and dwarfed new shoots, and phytohormones play a crucial role in the response to inversion. The polar auxin transport (PAT) system is distinct from the transport systems of other hormones and is controlled by three major transporter gene families: pin-formed (PIN), auxin-resistant/like aux (AUX/LAX) and ATP-binding cassette transporters of the B class (ABCB). Here, we identified these three families in P. trichocarpa, P. euphratica and P. yunnanensis through a genome-wide analysis. The Populus PIN, AUX/LAX and ABCB gene families comprised 15, 8 and 31 members, respectively. Most PAT genes in Populus and Arabidopsis were identified as clear sister pairs, and some had unique motifs. Transcriptome profiling revealed that the expression of most PAT genes was unrelated to cutting inversion and that only several genes showed altered expression when cuttings were inverted. The auxin content difference at positions was opposite in upright and inverted cutting bodies during rooting, which obeyed the original plant polarity. However, during plant growth, the two direction types exhibited similar auxin movements in the cutting bodies, and the opposite auxin changes were observed in new shoots. Four PAT genes with a positive response to cutting inversion, PyuPIN10, PyuPIN11, PyuLAX6 and PyuABCB27, showed diverse expression patterns between upright and inverted cuttings during rooting and plant growth. Furthermore, PAT gene expression retained its polarity, which differs from the results found for auxin flow during plant growth. The inconformity indicated that a new downward auxin flow in addition to the old upward flow might be established during the growth of inverted cuttings. Some highly polar PAT genes were involved in the maintenance of original auxin polarity, which might cause the enlarged stems of inverted cuttings. This work lays a foundation for understanding the roles of auxin transport in plant responses to inversion.

Keywords: ABCB; AUX/LAX; Inversion; PIN; Polar auxin transport; Populus.

MeSH terms

Gene Expression Profiling / methods*
Gene Expression Regulation, Developmental
Gene Expression Regulation, Plant
Indoleacetic Acids / metabolism*
Membrane Transport Proteins / genetics*
Membrane Transport Proteins / metabolism
Multigene Family
Phylogeny
Plant Proteins / genetics
Plant Proteins / metabolism
Populus / classification
Populus / genetics
Populus / growth & development*
Populus / metabolism
Whole Genome Sequencing

Substances

Indoleacetic Acids
Membrane Transport Proteins
Plant Proteins