TY - GEN T1 - Expression of the DELLA repressor GAI and its regulators SPY and SEC are impacted by disruption of chromatin modifiers AU - Trachtman, Natalie AU - Sockler, Patrick AU - Caiola, Hanna AU - McCain, Elizabeth R AU - Hark, Amy T DO - 10.17912/MICROPUB.BIOLOGY.000175 UR - https://www.micropublication.org/journals/biology/micropub.biology.000175 AB - Since trichome number is altered with disruption of GCN5 or ADA2b (Kotak et al. 2019; Wang et al. 2019), we sought to determine whether these chromatin factors might impact the expression of known regulators of trichome initiation, including two members of the DELLA family of repressor proteins, GA-Insensitive (GAI) and REPRESSOR of ga1-3 (RGA).  As their names suggest, these proteins are sensitive to gibberellin (GA) signaling (Silverstone et al. 2001).  GA complexed with its receptor can bind to DELLA proteins and promote their interaction with a component of an E3 ubiquitin ligase, SLEEPY1 (SLY1), leading to subsequent proteasome-media degradation (Dill et al. 2004).  In addition to SLY1, we also assessed the expression of SPINDLY (SPY) and SECRET AGENT (SEC), both known to covalently modify RGA and impact its functionality in a positive and negative manner respectively (Zentella et al. 2016, 2017). In mature rosette leaves of gcn5-6 plants (harboring a T-DNA insertion that disrupts the catalytic domain of GCN5; Kotak et al. 2018), we detect a trend of decreased expression of GAI, while no consistent change in expression is seen for RGA.  Among the factors that influence the activity of the DELLA repressors, SLY1 showed no change in expression.  On average, there was a 1.5X increase in SPY expression in gcn5-6 mutants while SEC expression was more than doubled (Fig. 1A). Expression analysis comparing the Columbia (wildtype) and gcn5-6 background included five biological replicates, except for SLY1, where n=4. A microarray experiment conducted by Vlachonasios et al. 2003 provides some additional data on these genes’ expression in ADA2b and GCN5 disruption mutants.  Specifically, in ada2b-1 and gcn5-1 plants (Vlachonasios et al. 2003), GAI expression is slightly decreased (less than three-fold) while RGA expression is unchanged, paralleling what we report here with gcn5-6.  SLY1 expression was also slightly decreased in ada2b-1 and gcn5-1 plants.  Since SPY and SEC were not included in the microarray experiment, we assayed their expression via qRT-PCR.  SPY expression is unchanged in gcn5-1.  This is consistent with the lack of a significant change in gcn5-6 plants.  In ada2b-1 plants, SPY expression is increased more than 2-fold.  SEC expression is increased in both gcn5-1 and ada2b-1 in comparison to Ws (wildtype) controls.  These experiments included 4-6 biological replicates.     PY - 2019 PB - microPublication Biology ER -