Effects of karrikins and the strigolactone analogue GR24 on the transcriptome of Brachypodium distachyon seedlings

Objective: to compare and contrast the effects of exogenous application of karrikins KAR1 and KAR2, and the strigolatone analogue rac-GR24, on gene expression in shoot tissue of seedlings of Brachpodium distachyon (false brome). The experiment compared the effects on three genotypes: wild type Bd21-3, and two mutant alleles for the Brachypodium orthoologue of the karrikin receptor KARRIKIN INSENSITIVE2 (KAI2; Bradi1g15880.1). These alleles were designated Bdkai2-1 and Bdkai2-2. Four treatments (mock, 1 µM KAR1, 1 µM KAR2, 10 µM rac-GR24) were applied to three genotypes (WT Bd21-3, Bdkai2-1, Bdkai2-2) in triplicate, for a total of 36 samples. Three-day-old seedlings were transferred to liquid growth medium in 250 mL conical flasks for 24 hours, and then treated by addition of 1:1000 dilution of acetone (mock), 1 mM KAR1, 1 mM KAR2 or 10 mM rac-GR24 (all dissolved in acetone). Shoot material was collected after four hours of treatment and frozen in liquid nitrogen prior to extraction of total RNA.