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

First author: Sharmila Singh; Affiliations: National Institute of Plant Genome Research (印度国家植物基因组研究所): New Delhi, India

Corresponding author: Ananda K. Sarkar

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.

由各种生长素/吲哚-3-乙酸Aux/IAA和生长素响应因子ARF介导的生长素信号转导通过控制下游基因的表达来调节侧根的发育。LRP1基因是SHI/STY家族的成员，该基因属于生长素诱导型基因。但LRP1基因在根发育中的精确的发育功能以及分子调控仍有待了解。本文中，作者的研究显示LRP1基因除了在主根中表达，在侧根发育的所有阶段也都有表达。LRP1基因的表达受组蛋白去乙酰化的调节，并且该调控依赖于生长素。进一步的遗传互作试验表明，LRP1基因在侧根发育过程中作为生长素响应因子Aux/IAA-ARF模块的下游发挥作用。slr‐1和arf7arf19突变体正在发育的侧根中，生长激素介导的LRP1基因表达诱导消失。NPA处理研究表明LRP1基因在侧根建成细胞分化和不对称分裂后发挥功能。LRP1基因的过表达植株在I、IV和V时期侧根原基数量增加，导致形成的侧根密度降低，这表明其参与了侧根原基的发育。有趣的是，LRP1诱导的生长素合成相关基因YUC4的表达与LRP1过表达植株中内源生长素的积累增加有关。 LRP1与SHI/STY家族的SHI、STY1、SRS3、SRS6和SRS7蛋白相互作用，表明它们在根发育过程中可能存在冗余作用。本文的研究结果表明，生长素和组蛋白去乙酰化会影响LRP1基因的表达，并在侧根形成生长素应答模块下游通过调节拟南芥中的生长素稳态来负调控侧根原基的发育。

通讯：Ananda K. Sarkar（http://www.nipgr.ac.in/research/dr_asarkar.php）

个人简介：1996-1998年，印度国际大学，学士；1998-2000年，印度理工学院，硕士；2001-2006年，弗萊堡大学，博士；2006-2009年，美国冷泉港实验室，博士后。

研究方向：植物干细胞的遗传和表观调控。

doi: https://doi.org/10.1111/tpj.14520

Journal: the plant journal

Published online: October 16, 2019