Molecular Manipulation of MicroRNA397 Abundance Influences the Development and Salt Stress Response of <i>Arabidopsis thaliana</i>

• Main Authors: Duc Quan Nguyen, Christopher W. Brown, Joseph L. Pegler, Andrew L. Eamens, Christopher P. L. Grof
• Format: Article
• Language: English
• Published: MDPI AG 2020-10-01
• Series: International Journal of Molecular Sciences
• Subjects: <i>Arabidopsis thaliana</i>; <i>Setaria viridis</i>; microRNA397 (miR397); <i>LACCASE </i>(<i>LAC</i>); lignin; salt stress
• Online Access: https://www.mdpi.com/1422-0067/21/21/7879

<i>Arabidopsis thaliana</i> (<i>Arabidopsis</i>) has been used extensively as a heterologous system for molecular manipulation to genetically characterize both dicotyledonous and monocotyledonous plant species. Here, we report on <i>Arabidopsis</i> transformant lines molecularly manipulated to over-accumulate the small regulatory RNA microRNA397 (miR397) from the emerging C₄ monocotyledonous grass model species <i>Setaria viridis</i> (<i>S. viridis</i>). The generated transformant lines, termed <i>SvMIR397</i> plants, displayed a range of developmental phenotypes that ranged from a mild, wild-type-like phenotype, to a severe, full dwarfism phenotype. Reverse transcriptase quantitative polymerase chain reaction (RT-qPCR)-based profiling of the <i>SvMIR397</i> transformant population revealed a strong correlation between the degree of miR397 over-accumulation, repressed <i>LACCASE</i> (<i>LAC</i>) target gene expression, reduced lignin content, and the severity of the developmental phenotype displayed by <i>SvMIR397</i> transformants. Further, exposure of <i>SvMIR397</i> transformants to a 7-day regime of salt stress revealed the <i>SvMIR397</i> transformant lines to be more sensitive to the imposed stress than were wild-type <i>Arabidopsis</i> plants. Taken together, the findings reported here via the use of <i>Arabidopsis</i> as a heterologous system show that the <i>S. viridis</i> miR397 small regulatory RNA is able to repress the expression of three <i>Arabidopsis LAC</i> genes which led to reduced lignin content and increased salt stress sensitivity.