AUTHOR=Shi Gege , Wang Saisai , Wang Peng , Zhan Jingjing , Tang Ye , Zhao Ge , Li Fuguang , Ge Xiaoyang , Wu Jiahe 

TITLE=Cotton miR393-TIR1 Module Regulates Plant Defense Against Verticillium dahliae via Auxin Perception and Signaling

JOURNAL=Frontiers in Plant Science

VOLUME=13

YEAR=2022

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2022.888703

DOI=10.3389/fpls.2022.888703

ISSN=1664-462X

ABSTRACT=<p>Plant auxin is essential in plant growth and development. However, the molecular mechanisms of auxin involvement in plant immunity are unclear. Here, we addressed the function of the cotton (<italic>Gossypium hirsutum</italic>) miR393-TIR1 module in plant defense against <italic>Verticillium dahliae</italic> infection via auxin perception and signaling. <italic>GhTIR1</italic> was directedly cleaved by ghr-miR393 according to mRNA degradome data, 5′-RACE analysis, and a GUS reporter assay. Ghr-miR393 knockdown significantly increased plant susceptibility to <italic>V. dahliae</italic> compared to the control, while ghr-miR393 overexpression and <italic>GhTIR1</italic> knockdown significantly increased plant resistance. External indole-3-acetic acid (IAA) application significantly enhanced susceptibility to <italic>V. dahliae</italic> in ghr-miR393 knockdown and control plants compared to mock treatment, and only slightly increased susceptibility in overexpressing ghr-miR393 and GhTIR1-silenced plants. Application of external PEO-IAA (an auxin antagonist) had a contrary trend with IAA application. Based on yeast two-hybrid and bimolecular fluorescence complementation assays, GhTIR1 interacted with GhIAA14 in the nucleus, and <italic>GhIAA14</italic> knockdown reduced plant resistance to <italic>V. dahliae</italic> infection. The results suggested that the ghr-miR393-GhTIR1 module regulates plant defense via auxin perception and signaling. Additionally, simultaneous knockdown of <italic>GhTIR1</italic> and <italic>GhICS1</italic> significantly increased plant susceptibility to <italic>V. dahliae</italic> compared to the control, indicating that salicylic acid (SA) accumulation is vital for the ghr-miR393-GhTIR1 module to regulates plant resistance. Transcriptome data also demonstrated that <italic>GhTIR1</italic> knockdown significantly downregulated expression of auxin-related genes and upregulated expression of SA-related genes. Overall, the ghr-miR393-GhTIR1 module participates in plant response to <italic>V. dahliae</italic> infection via IAA perception and signaling partially depending on the SA defense pathway.</p>