Internalization of miPEP165a into Arabidopsis Roots Depends on both Passive Diffusion and Endocytosis-Associated Processes

Abstract

MiPEPs are short natural peptides encoded by microRNAs in plants. Exogenous application of miPEPs increases the expression of their corresponding miRNA and, consequently, induces consistent phenotypical changes. Therefore, miPEPs carry huge potential in agronomy as gene regulators that do not require genome manipulation. However, to this end, it is necessary to know their mode of action, including where they act and how they enter the plants. Here, after analyzing the effect of Arabidopsis thaliana miPEP165a on root and aerial part development, we followed the internalization of fluorescent-labelled miPEP165a into roots and compared its uptake into endocytosis-altered mutants to that observed in wild-type plants treated or not with endocytosis inhibitors. The results show that entry of miPEP165a involves both a passive diffusion at the root apex and endocytosis-associated internalization in the differentiation and mature zones. Moreover, miPEP165a is unable to enter the central cylinder and does not migrate from the roots to the aerial part of the plant, suggesting that miPEPs have no systemic effect.

Possible functions of the conserved peptide encoded by the RNA-precursor of miR-156a in plants of the familyBrassicaceae

“…The observed localization of miPEP156a in the nuclei of cabbage plant cells, which was not detected in the case of miPEP165a in A. thaliana (Ormancey et al, 2020), indicates the ability of miPEP156a peptide to efficient nuclear-cytoplasmic transport. The mechanisms of such transport are very conservative in plants and animals (Sorokin et al, 2007; Merkle, 2011).…”

“…It is important that during these processes, miPEP165a cannot penetrate the central cylinder of the root, so it does not enter the phloem. It is correlated with the fact that peptide does not migrate from the roots to the upper part of the plant (Ormancey et al, 2020). Our experiments with the penetration of miPEP156a into cabbage seedlings revealed a different picture.…”

“…Finding of the physiological effect of exogenous miPEP156a on plant growth indicates its ability to penetrate the tissues of seedlings. Previously, this effect was studied in detail on the example of miPEP165a in A. thaliana (Ormancey et al, 2020). This published study used a peptide labeled with a fluorescent dye.…”

Coding of Non-coding RNA: Insights Into the Regulatory Functions of Pri-MicroRNA-Encoded Peptides in Plants

“…On the other hand, the upstream of pre-miRNA containing short ORF is possibly polyadenylated for preventing degradation (I) and is exported to cytoplasm for guiding miPEPs synthesis. External miPEPs are supposed to internalize into cytoplasm by endocytosis-associated processes (II) and passive diffusion (III) ( Ormancey et al, 2020 ; Sharma et al, 2020 ). MiPEPs maybe function to transcription factors (TFs), which regulate the transcription of MIR genes (IV and V), resulting in upregulated expression of associated miRNA.…”

Cell Signaling in Model Plants

“…MicroRNAs (miRNAs) play a significant role in the regulation of gene expression. Ormancey et al investigated the role of a miRNA-encoded peptide, miPEP165a, in A. thaliana [ 6 ]. The authors found that passive diffusion followed by an endocytosis process are two functions of entry of miPEP165a.…”