Auxin signaling modulates LATERAL ROOT PRIMORDIUM1 (LRP1) expression during lateral root development in Arabidopsis

• Published in: The Plant journal : for cell and molecular biology Vol. 101; no. 1; pp. 87 - 100
• Main Authors: Singh, Sharmila, Yadav, Sandeep, Singh, Alka, Mahima, Mahima, Singh, Archita, Gautam, Vibhav, Sarkar, Ananda K.
• Format: Journal Article
• Language: English
• Published: England Blackwell Publishing Ltd 01.01.2020
• Subjects: Acetic acid; Arabidopsis; auxin; Biosynthesis; Deacetylation; epigenetic regulation; Gene expression; Histones; Homeostasis; Indoleacetic acid; lateral root; LRP1; Modules; Mutants; Primordia; Root development; Roots; SHI/STY; Signaling; SHI/STY; LRP1; auxin; Arabidopsis; epigenetic regulation; lateral root
• ISSN: 0960-7412; 1365-313X
• DOI: 10.1111/tpj.14520

Summary Auxin signaling mediated by various auxin/indole‐3‐acetic acid (Aux/IAAs) and AUXIN RESPONSE FACTORs (ARFs) regulate lateral root (LR) development by controlling the expression of downstream genes. LATERAL ROOT PRIMORDIUM1 (LRP1), a member of the SHORT INTERNODES/STYLISH (SHI/STY) family, was identified as an auxin‐inducible gene. The precise developmental role and molecular regulation of LRP1 in root development remain to be understood. Here we show that LRP1 is expressed in all stages of LR development, besides the primary root. The expression of LRP1 is regulated by histone deacetylation in an auxin‐dependent manner. Our genetic interaction studies showed that LRP1 acts downstream of auxin responsive Aux/IAAs‐ARFs modules during LR development. We showed that auxin‐mediated induction of LRP1 is lost in emerging LRs of slr‐1 and arf7arf19 mutants roots. NPA treatment studies showed that LRP1 acts after LR founder cell specification and asymmetric division during LR development. Overexpression of LRP1 (LRP1 OE) showed an increased number of LR primordia (LRP) at stages I, IV and V, resulting in reduced emerged LR density, which suggests that it is involved in LRP development. Interestingly, LRP1‐induced expression of YUC4, which is involved in auxin biosynthesis, contributes to the increased accumulation of endogenous auxin in LRP1 OE roots. LRP1 interacts with SHI, STY1, SRS3, SRS6 and SRS7 proteins of the SHI/STY family, indicating their possible redundant role during root development. Our results suggested that auxin and histone deacetylation affect LRP1 expression and it acts downstream of LR forming auxin response modules to negatively regulate LRP development by modulating auxin homeostasis in Arabidopsis thaliana. Significance Statement The molecular regulation and role of SHI/STY family genes, such as LRP1, in root development are poorly understood. Here, we show that LRP1 is involved in auxin‐mediated lateral root development by acting downstream of Aux/IAA‐ARFs modules. Trichostatin A, a histone deacetylase (HDAC) inhibitor, reduces the auxin‐induced expression of LRP1, indicating its epigenetic regulation. LRP1 promotes auxin biosynthesis through transcriptional induction of YUC4. LRP1 interacts with SHI/STY family members, indicating possible redundant functions in a multiprotein complex.