Abstract:The biological significance of non-coding RNAs (ncRNAs) has been firmly established to be important for the regulation of genes involved in stress acclimation. Light plays an important role for the growth of plants providing the energy for photosynthesis; however, excessive light conditions can also cause substantial defects. Small RNAs (sRNAs) are a class of non-coding RNAs that regulate transcript levels of protein-coding genes and mediate epigenetic silencing. Next generation sequencing facilitates the iden… Show more
“…1 d). The involvement of miR163 and miR840 in the HL response is not surprising because miR163 was previously found to be induced by light during seedling de-etiolation [ 47 , 48 ] after 6 h of HL [ 12 ] or red light treatment [ 49 ], and miR840 was described as a gamma-ray-responsive miRNA [ 16 ]. Fig.…”
Section: Resultsmentioning
confidence: 99%
“…For example, far-red light-responsive miRNAs were described in soybean [ 10 ]. Nevertheless, there is almost no information about miRNA expression changes under high light (HL) conditions except studies on Dendrocalamus latiflorus , an important Asian bamboo species [ 11 ], a recent report describing small RNAs during high light acclimation [ 12 ] and the systemic miRNA response in Arabidopsis thaliana roots [ 13 ]. Additionally, there are some reports on UV-A-, UV-B-, and gamma radiation-regulated miRNAs [ 14 – 18 ].…”
Background
MicroRNAs (miRNAs) are a class of endogenous noncoding RNAs that play a pivotal role in the regulation of plant development and responses to the surrounding environment. Despite the efforts made to elucidate their function in the adaptation of plants to many abiotic and biotic stresses, their role in high light (HL) stress is still vague. HL stress often arises upon plant exposure to full sunlight. Subsequent changes in nuclear gene expression are triggered by chloroplast-derived retrograde signals.
Results
In this study, we show that HL is involved in miRNA-dependent regulation in Arabidopsis thaliana rosettes. Microtranscriptomic screening revealed a limited number of miRNAs reacting to HL. To explain the miRNA regulation mechanisms at the different biogenesis stages, chemical and genetic approaches were applied. First, we tested the possible role of plastoquinone (PQ) redox changes using photosynthetic electron transport chain inhibitors. The results suggest that increased primary transcript abundance (pri-miRNAs) of HL-regulated miRNAs is dependent on signals upstream of PQ. This indicates that such signals may originate from photosystem II, which is the main singlet oxygen (1O2) source. Nevertheless, no changes in pri-miRNA expression upon a dark–light shift in the conditional fluorescent (flu) mutant producing 1O2 were observed when compared to wild-type plants. Thus, we explored the 1O2 signaling pathway, which is initiated independently in HL and is related to β-carotene oxidation and production of volatile derivatives, such as β-cyclocitral (β-CC). Pri-miRNA induction by β-CC, which is a component of this 1O2 pathway, as well as an altered response in the methylene blue sensitivity 1 (mbs1) mutant support the role of 1O2 signaling in miRNA regulation.
Conclusions
We show that light stress triggers changes in miRNA expression. This stress response may be regulated by reactive oxygen species (ROS)-related signaling. In conclusion, our results link ROS action to miRNA biogenesis, suggesting its contribution to inconsistent pri- and mature miRNA dynamics.
“…1 d). The involvement of miR163 and miR840 in the HL response is not surprising because miR163 was previously found to be induced by light during seedling de-etiolation [ 47 , 48 ] after 6 h of HL [ 12 ] or red light treatment [ 49 ], and miR840 was described as a gamma-ray-responsive miRNA [ 16 ]. Fig.…”
Section: Resultsmentioning
confidence: 99%
“…For example, far-red light-responsive miRNAs were described in soybean [ 10 ]. Nevertheless, there is almost no information about miRNA expression changes under high light (HL) conditions except studies on Dendrocalamus latiflorus , an important Asian bamboo species [ 11 ], a recent report describing small RNAs during high light acclimation [ 12 ] and the systemic miRNA response in Arabidopsis thaliana roots [ 13 ]. Additionally, there are some reports on UV-A-, UV-B-, and gamma radiation-regulated miRNAs [ 14 – 18 ].…”
Background
MicroRNAs (miRNAs) are a class of endogenous noncoding RNAs that play a pivotal role in the regulation of plant development and responses to the surrounding environment. Despite the efforts made to elucidate their function in the adaptation of plants to many abiotic and biotic stresses, their role in high light (HL) stress is still vague. HL stress often arises upon plant exposure to full sunlight. Subsequent changes in nuclear gene expression are triggered by chloroplast-derived retrograde signals.
Results
In this study, we show that HL is involved in miRNA-dependent regulation in Arabidopsis thaliana rosettes. Microtranscriptomic screening revealed a limited number of miRNAs reacting to HL. To explain the miRNA regulation mechanisms at the different biogenesis stages, chemical and genetic approaches were applied. First, we tested the possible role of plastoquinone (PQ) redox changes using photosynthetic electron transport chain inhibitors. The results suggest that increased primary transcript abundance (pri-miRNAs) of HL-regulated miRNAs is dependent on signals upstream of PQ. This indicates that such signals may originate from photosystem II, which is the main singlet oxygen (1O2) source. Nevertheless, no changes in pri-miRNA expression upon a dark–light shift in the conditional fluorescent (flu) mutant producing 1O2 were observed when compared to wild-type plants. Thus, we explored the 1O2 signaling pathway, which is initiated independently in HL and is related to β-carotene oxidation and production of volatile derivatives, such as β-cyclocitral (β-CC). Pri-miRNA induction by β-CC, which is a component of this 1O2 pathway, as well as an altered response in the methylene blue sensitivity 1 (mbs1) mutant support the role of 1O2 signaling in miRNA regulation.
Conclusions
We show that light stress triggers changes in miRNA expression. This stress response may be regulated by reactive oxygen species (ROS)-related signaling. In conclusion, our results link ROS action to miRNA biogenesis, suggesting its contribution to inconsistent pri- and mature miRNA dynamics.
“…Oryza sativa subjected to continuous dark treatment showed a decrease in the catalase gene ( Cat B ) expression in roots caused by an accumulation of Cat B sense and antisense unspliced transcripts, detected by RNA dot-plot hybridization [ 36 ]. In contrast, Tiwari et al [ 100 ] used strand-specific RNAseq to investigate small RNA induced by high light acclimation in A. thaliana and detected NATs and double-strand RNAs derived from NATs.…”
Initially, natural antisense transcripts (NATs, natRNAs, or asRNAs) were considered repressors; however, their functions in gene regulation are diverse. Positive, negative, or neutral correlations to the cognate gene expression have been noted. Although the first studies were published about 50 years ago, there is still much to be investigated regarding antisense transcripts in plants. A systematic review of scientific publications available in the Web of Science databases was conducted to contextualize how the studying of antisense transcripts has been addressed. Studies were classified considering three categories: “Natural antisense” (208), artificial antisense used in “Genetic Engineering” (797), or “Natural antisense and Genetic Engineering”-related publications (96). A similar string was used for a systematic search in the NCBI Gene database. Of the 1132 antisense sequences found for plants, only 0.8% were cited in PubMed and had antisense information confirmed. This value was the lowest when compared to fungi (2.9%), bacteria (2.3%), and mice (54.1%). Finally, we present an update for the cis-NATs identified in Saccharum spp. Of the 1413 antisense transcripts found in different experiments, 25 showed concordant expressions, 22 were discordant, 1264 did not correlate with the cognate genes, and 102 presented variable results depending on the experiment.
“…Previous reports also revealed that sRNAs are crucial for abiotic stress tolerance mechanisms in various plant species (Fu et al, 2017, Tiwari et al, 2021 and due to the anticipated adjustment and/or misregulation of sRNA biogenesis and sRNA-directed gene regulatory networks, we hypothesized that plants with mutated MpDCLs would have altered abiotic stress tolerance. High salinity is one of the most severe abiotic stresses that induces global transcriptomic changes and adversely affects plant growth and development (Golldack et al, 2011, Fu et al, 2017, Tanaka et al, 2018.…”
Section: Effects Of Mpdcl Mutations On Thallus Developmentmentioning
DICER-LIKE (DCL) proteins have a central role in plant small RNA (sRNA) biogenesis. The Marchantia polymorpha genome encodes four DCL proteins: two DCL1 homologs, MpDCL1a and MpDCL1b, MpDCL3 and MpDCL4. While MpDCL1a, MpDCL3 and MpDCL4 show high similarities to their orthologs in Physcomitrium patens and Arabidopsis thaliana, MpDCL1b shares only a limited homology with PpDCL1b, but it is very similar, in terms of functional domains, to orthologs in Anthoceros agrestis and Salvinia cucullata. We generated Mpdclge mutant lines via the CRISPR/Cas9 system and performed comprehensive phenotypic analyses of these mutant lines, under control and salt stress conditions as well as upon exogenous naphthaleneacetic acid (NAA) and abscisic acid (ABA) treatments to gain insights into the respective MpDCL functions. While Mpdcl1age mutants display severe developmental aberrations throughout their development, no adverse phenotypic changes are detectable in Mpdcl1bge and Mpdcl4ge mutants except the development of less and smaller male sexual organs (antheridiophores) when they are cultivated under photoperiod conditions supplemented with far-red light. Mpdcl3ge mutants display rosette-shaped thallus formation and overall faster development, but are not able to form antheridiophores. The rosette-shaped thallus development of Mpdcl3ge can be reverted to a wild-type-like thallus growth upon NAA treatment. Mpdcl1bge mutants can tolerate high levels of salt, whereas Mpdcl4ge mutants show higher salt sensitivity. Moreover, Mpdcl1age and Mpdcl3ge mutants show an ABA-hypersensitive phenotype. It can be concluded that the observed phenotypic alterations, under normal or treatment conditions, are linked to the mutations in the respective MpDCLs and hence to defective or altered sRNA biogenesis pathways in M. polymorpha. In conclusion, MpDCLs and their associated sRNAs regulate development, abiotic stress and phytohormonal response in M. polymorpha.
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