Roles of microRNAs in abiotic stress response and characteristics regulation of plant

Abstract

MicroRNAs (miRNAs) are a class of non-coding endogenous small RNAs (long 20-24 nucleotides) that negatively regulate eukaryotes gene expression at post-transcriptional level via cleavage or/and translational inhibition of targeting mRNA. Based on the diverse roles of miRNA in regulating eukaryotes gene expression, research on the identification of miRNA target genes has been carried out, and a growing body of research has demonstrated that miRNAs act on target genes and are involved in various biological functions of plants. It has an important influence on plant growth and development, morphogenesis, and stress response. Recent case studies indicate that miRNA-mediated regulation pattern may improve agronomic properties and confer abiotic stress resistance of plants, so as to ensure sustainable agricultural production. In this regard, we focus on the recent updates on miRNAs and their targets involved in responding to abiotic stress including low temperature, high temperature, drought, soil salinity, and heavy metals, as well as plant-growing development. In particular, this review highlights the diverse functions of miRNAs on achieving the desirable agronomic traits in important crops. Herein, the main research strategies of miRNAs involved in abiotic stress resistance and crop traits improvement were summarized. Furthermore, the miRNA-related challenges and future perspectives of plants have been discussed. miRNA-based research lays the foundation for exploring miRNA regulatory mechanism, which aims to provide insights into a potential form of crop improvement and stress resistance breeding.

Keywords: abiotic stress; agronomic trait; growing development; microRNA; target gene.

Figure 1

Regulatory network of the miRNAs involved in low-temperature stress primarily by phytohormone signal transduction and ROS scavenging mechanism in plants. Cold stress-responsive miRNAs in Arabidopsis, potato, and rice are shown in the chart. The arrows and hammer represent positive and negative regulation, respectively. AUX/IAA, Auxin/indole acetic acid; NF-YA, nuclear factor Y subunit A; YUC2, flavin-binding monooxygenase family protein 2; ABF, auxin F-box protein; AAO, abscisic-aldehyde oxidase; TCP, teosinte branched (tb1)-cycloidea (CYC)-proliferating cell factors1 and 2 (PCF1 and PCF2) transcription factor; ABA, abscisic acid; GA, gibberellin; ROS, reactive oxygen species.

Figure 2

Schematic diagram exhibited that multiple miRNAs in response to high-temperature stress in several plants. (A) MiRNAs display tissue-specific expression under heat stress in tomato and through regulating different metabolic pathways to resist high temperature. Also, miRNAs expression is affected by moderately or acutely elevated temperature. (B) Certain miRNAs are showed downregulated expression suffered heat treatment in wheat. (C) Effect on expression of miRNAs and their corresponding targets under heat surrounding conditions in maize. (D) MiRNAs show specific expression in critical developmental period of cotton anther to adapt to high-temperature stress. SCP, sporogenous cell proliferation stage; MP, meiotic phase stage; MRP, microspore release period; PM, pollen maturity stage. miRNAs upregulated expression and downregulated expression are represented by upward and downward arrows in the circle, respectively. AUX, auxin; ROS, reactive oxygen species; MYB, MYB proto-oncogene transcription factor; SBP/SPL, SQUAMOSA promoter-binding proteins; AP2/ERF, ethylene response factor; NAC, NAM, ATAF and CUC (NAC) transcription factors; HD-ZIP, zipper motif (LZ) immediately downstream of the home domain; GRF, growth-regulating factor1; SAC2, adenylate cyclase.

Figure 3

Schematic diagram of the drought-responsive miRNAs in plants are primarily by phytohormone ABA-mediated and non-ABA-mediated pathways initiating an adaptive response to enhance drought tolerance. The miRNAs in red and blue font were upregulated and downregulated under drought stress, respectively. The arrows and hammer represent positive and negative regulation, respectively. OE, overexpression; MYB, MYB proto-oncogene transcription factor; NF-YA, nuclear factor Y subunit A; HD-ZIPIII, zipper motif (LZ) immediately downstream of the home domain; NAC, NAM, ATAF, and CUC (NAC) transcription factors; CCS, copper chaperone for superoxide dismutase; CSD, copper-zinc superoxide dismutase 1and 2; SPL/SBP, SQUAMOSA promoter-binding proteins; TIR, transport inhibitor response; ARF, auxin response factors; POD, peroxidase; ABA, abscisic acid.

Figure 4

MiRNA-mediated regulating network responses salt stress in plants. The arrows and hammer represent positive and negative regulation, respectively. OE, overexpression; ROS, reactive oxygen species; ETH, ethylene; ABA, abscisic acid; FSD1, iron superoxide dismutase 1; IDS1, INDETERMINATE SPIKELET 1; LAC, LACCASE enzymes; TCP/PCF, teosinte branched (tb1)-cycloidea (CYC)-proliferating cell factors1 and 2 (PCF1 and PCF2) transcription factor; RACK1A, receptor for activated C kinase 1; WRKY, WRKY transcription factors; TIR, transport inhibitor response; AFB, auxin F-box protein.

Figure 5

MiRNAs and/or their target genes regulate multiple agronomic traits of plants. Primarily for quality and yield of agronomic important plant, ideal plant architecture, abiotic stress resistance, male sterility, and flowering time.