Taeyoung Um, Joohee Choi, Taehyeon Park, Pil Joong Chung, Se Eun Jung, Jae Sung Shim, Youn Shic Kim, Ik-Young Choi, Soo Chul Park, Se-Jun Oh, Jun Sung Seo, Ju-Kon Kim

Plant Direct.; 2022 Jan 9;6(1):e374. doi: 10.1002/pld3.374. eCollection 2022 Jan.

Abstract

Plants have evolved sophisticated defense systems to enhance drought tolerance. These include the microRNA (miRNA) group of small noncoding RNAs that act as post-transcriptional regulators; however, details of the mechanisms by which they confer drought tolerance are not well understood. Here, we show that osa-MIR171f, a member of osa-MIR171 gene family, is mainly expressed in response to drought stress and regulates the transcript levels of SCARECROW-LIKE6-I (SCL6-I) and SCL6-II in rice (Oryza sativa). The SCL6 genes are known to be involved in shoot branching and flag leaf morphology. Osa-MIR171f-overexpressing (osa-MIR171f-OE) transgenic plants showed reduced drought symptoms compared with non-transgenic (NT) control plants under both field drought and polyethylene glycol (PEG)-mediated dehydration stress conditions. Transcriptome analysis of osa-MIR171f-OE plants and osa-mir171f-knockout (K/O) lines generated by clustered regularly interspaced short palindromic repeats (CRISPR/Cas9) revealed that osa-mature-miR171a-f (osa-miR171) regulates the expression of flavonoid biosynthesis genes, consequently leading to drought tolerance. This upregulation in the osa-MIR171f-OE plants, which did not occur in NT control plants, was observed under both normal and drought conditions. Our findings indicate that osa-miR171 plays a role in drought tolerance by regulating SCL6-I and SCL6-II transcript levels.

See: https://pubmed.ncbi.nlm.nih.gov/35028494/

Figure 1: Analysis of osa‐pre‐miR171f and osa‐mature‐microRNA171a‐f (osa‐miR171) response to abiotic stress in rice. (a and b) Reverse transcription‐quantitative polymerase chain reaction (RT‐qPCR) analysis showing changes in osa‐pre‐miR171f expression levels in response to different stresses in shoots (a) and roots (b). Control plants were not treated with drought stress (0 h time). Error bars indicate SD of triplicate measurements. OsTubA2 and OsUbi1 were used as internal controls, and relative expression levels are shown as fold values. Asterisks indicate statistically significant differences between the corresponding samples and their control (p value < .01, Student's t test). ABA, abscisic acid. (c and d) osa‐miR171 expression levels in seedlings (c) and young plants (d) under drought stress. The expression level was assessed by Northern blot analysis. U6 transcript levels show equal loading of RNA. Total RNA was prepared from the 10‐day‐old and 4‐week‐old plants exposed to stresses for the indicated time periods