Knockdown of miR393 Promotes the Growth and Biomass Production in Poplar

Liwei Chu; Xuejiao He; Wenbo Shu; Lijuan Wang; Fang Tang

doi:10.3389/fpls.2021.714907

Knockdown of miR393 Promotes the Growth and Biomass Production in Poplar

Front Plant Sci. 2021 Jul 14:12:714907. doi: 10.3389/fpls.2021.714907. eCollection 2021.

Authors

Liwei Chu¹, Xuejiao He¹, Wenbo Shu², Lijuan Wang^{1

3}, Fang Tang^{1

3}

Affiliations

¹ State Key Laboratory of Tree Genetics and Breeding, Key Laboratory of Tree Breeding and Cultivation of the National Forestry and Grassland Administration, Research Institute of Forestry, Chinese Academy of Forestry, Beijing, China.
² Key Laboratory of Horticultural Plant Biology of Ministry of Education, College of Horticulture and Forestry Sciences, Huazhong Agricultural University, Wuhan, China.
³ Co-innovation Center for Sustainable Forestry in Southern China, Nanjing Forestry University, Nanjing, China.

Abstract

Short tandem target mimic (STTM), which is composed of two short sequences mimicking small RNA target sites, separated by a linker of optimal size, can block the functions of all members in a miRNA family. microRNA393 (miR393), which is one of the conserved miRNA families in plants, can regulate plant root growth, leaf development, plant architecture, and stress resistance. In order to verify the role of miR393 in the secondary growth of trees, we created its STTM transgenic poplar lines (STTM393). The expression of miR393 in STTM393 lines was reduced by over 10 times compared with the control plants. STTM393 lines showed promoted growth with about 20% higher, 15% thicker, and 2-4 more internodes than the control plants after 3 months of growth. The cross-section of the stems showed that STTM393 lines had wider phloem, xylem, and more cambium cell layers than control plants, and the lignin content in STTM393 lines was also higher as revealed by staining and chemical determination. Based on the transcriptome analysis, the genes related to the auxin signaling pathway, cell cyclin, cell expansion, and lignin synthesis had higher expression in STTM393 lines than that in control plants. The higher expression levels of FBL family members suggested that the auxin signaling pathway was strengthened in STTM393 lines to promote plant growth. Therefore, the knockdown of miR393 using the STTM approach provides a way to improve poplar growth and biomass production.

Keywords: RNA-seq; STTM; auxin signaling pathway; miR393; plant growth; poplar.