An Antisense Circular RNA Regulates Expression of RuBisCO Small Subunit Genes in Arabidopsis

He Zhang; Shuai Liu; Xinyu Li; Lijuan Yao; Hongyang Wu; František Baluška; Yinglang Wan

doi:10.3389/fpls.2021.665014

An Antisense Circular RNA Regulates Expression of RuBisCO Small Subunit Genes in Arabidopsis

Front Plant Sci. 2021 May 24:12:665014. doi: 10.3389/fpls.2021.665014. eCollection 2021.

Authors

He Zhang^{1

2}, Shuai Liu³, Xinyu Li¹, Lijuan Yao¹, Hongyang Wu⁴, František Baluška⁵, Yinglang Wan^{1

4}

Affiliations

¹ Hainan Key Laboratory for Sustainable Utilization of Tropical Bioresources, College of Tropical Crops, Hainan University, Haikou, China.
² Environment and Plant Protection Institute, Chinese Academy of Tropical Agricultural Sciences, Haikou, China.
³ State Key Laboratory of Tree Genetics and Breeding, Chinese Academy of Forestry, Beijing, China.
⁴ College of Biological Sciences and Technology, Beijing Forestry University, Beijing, China.
⁵ Institute of Molecular and Cellular Botany, Bonn University, Bonn, Germany.

Abstract

Circular RNA (circRNA) is a novel class of endogenous long non-coding RNA (lncRNA) and participates in diverse physiological process in plants. From the dataset obtained by high-throughput RNA sequencing, we identified a circRNA encoded by the sense strand of the exon regions spanning two RuBisCO small subunit genes, RBCS2B and RBCS3B, in Arabidopsis thaliana. We further applied the single specific primer-polymerase chain reaction (PCR) and Sanger sequencing techniques to verify this circRNA and named it ag-circRBCS (antisense and across genic-circular RNA RBCS). Using quantitative real-time PCR (qRT-PCR), we found that ag-circRBCS shares a similar rhythmic expression pattern with other RBCS genes. The expression level of ag-circRBCS is 10-40 times lower than the expression levels of RBCS genes in the photosynthetic organs in Arabidopsis, whereas the Arabidopsis root lacked ag-circRBCS expression. Furthermore, we used the delaminated layered double hydroxide lactate nanosheets (LDH-lactate-NS) to deliver in vitro synthesized ag-circRBCS into Arabidopsis seedlings. Our results indicate that ag-circRBCS could significantly depress the expression of RBCS. Given that ag-circRBCS was expressed at low concentration in vivo, we suggest that ag-circRBCS may represent a fine-tuning mechanism to regulating the expression of RBCS genes and protein content in Arabidopsis.

Keywords: Arabidopsis thaliana; RBCS; across-genic RNA; antisense RNA; circular RNA; expression regulation.