Transcriptome profiling provides insight into root development at low temperature by chimeric metacaspase for directing Pep1 formation

Abstract

Plant elicitor peptides (Peps) and low temperatures have both emerged as important regulators of root development. The intracellular formation of Pep1 by metacaspase 4 at low temperature is expectedly linked to root-growth regulation. Here, we engineered a chimeric metacaspase 4 (cMC4) protein with altered structure by substituting linker of MC4 with linker of MC7 to efficiently direct Pep1 generation at low temperature (15 °C). Arabidopsis seedlings exhibited significantly root length inhibition at low temperature by incubating with in vitro Pep1 producing solution from cMC4-mediated cleavage, which was simulated as intracellular Pep1 of damaged root cell. Further investigation of root transcriptomic profiling for these treated seedlings indicated that low-temperature-responsive genes involving in cellular ion/cation homeostasis, response to karrikin, plant-type vacuole and cell wall, along with metabolic networks of protein processing in endoplasmic reticulum and phenylpropanoid biosynthesis potentially contributed to low-temperature resistance of Arabidopsis root. Root-developmental-response genes of pollen tube growth, meristem growth, root hair cell development, and cell projection, along with ubiquitin mediated proteolysis pathways and defense-related genes were positively correlated with Pep1 generation pattern for triggering defense response. To the best of our knowledge, this is the first time to engineer chimeric protein to strengthen Pep1-triggered immunity for root development at low temperature, which could provide a potential clue for controlling root growth against stress.