Overexpression of miR390b promotes stem elongation and height growth in Populus

Abstract

MicroRNA390 (miR390) is involved in plant growth and development by down-regulating the expression of the downstream genes trans-acting short interfering RNA3 (TAS3) and AUXIN RESPONSE FACTORs (ARFs). There is a scarcity of research on the involvement of the miR390-TAS3-ARFs pathway in the stem development of Populus. Here, differentially expressed miRNAs during poplar stem development were screened by small RNA sequencing analysis, and a novel function of miR390b in stem development was revealed. Overexpression of miR390b (OE-miR390b) resulted in a large increase in the number of xylem fiber cells and a slight decrease in the cell length at the longitudinal axis. Overall increases in stem elongation and plant height were observed in the OE-miR390b plants. According to transcriptome sequencing results and transient co-expression analysis, TAS3.1 and TAS3.2 were identified as the target genes of miR390 in poplar and were negatively regulated by miR390 in the apex. The transcription levels of ARF3.2 and ARF4 were significantly repressed in OE-miR390b plants and strongly negatively correlated with the number of xylem fiber cells along the longitudinal axis. These findings indicate that the conserved miR390-TAS3-ARFs pathway in poplar is involved in stem elongation and plant height growth.

Transcriptome and miRNAs Profiles Reveal Regulatory Network and Key Regulators of Secondary Xylem Formation in “84K” Poplar

“…Small RNA sequencing (RNA-seq) has become a useful tool for the rapid discovery of miRNAs and can be used to identify important miRNAs associated with plant growth and development [14]. For example, a total of 85 xylem-specific differentially expressed miRNAs (DEMs) were identified by small RNA-seq analyses of xylem, phloem, and leaves in hybrid poplar (P. alba × P. glandulosa), which were thought to be potentially involved in regulating secondary xylem formation [15]; 75 DEMs associated with stem secondary growth were identified by small RNA-seq in P. deltoids [16]. However, little is currently known about which miRNAs are involved in regulating the transition from primary to secondary growth in poplar stems and which genes these miRNAs target are involved in these developmental processes.…”

Comparative Microscopic, Transcriptome and IAA Content Analyses Reveal the Stem Growth Variations in Two Cultivars Ilex verticillata

“…In addition to supporting the plant, the vascular system of the stem also functions to transport water and mineral nutrients [ 4 ]. The elongation of plant stems is caused by a combination of cell division and cell elongation, and elongation growth usually occurs during the transition from primary to secondary stem growth [ 5 ]. Plant stem elongation is regulated and controlled by various internal and external factors, among which the internal regulation of endogenous plant hormones such as gibberellin (GAs), brassinosteroid (BRs), strigolactone (SL) and auxin play an important role.…”