Bnasdg8s-Mediated H3k36me3 is Required for Freezing Tolerance in Brassica Napus

Abstract

Freezing stress is a harmful regulator affecting the growth and development of rapeseed ( Brassica napus L.). Plants modulate the transcriptome to combat freezing stress in order to minimize the impacts on the fitness. BnaSDG8 s including BnaSDG8.A and BnaSDG8.C are putative histone 3 lysine 36 tri-methyltransferase (H3K36me3) in Brassica napus . The H3K36me3 is an active histone mark at the FLC ( FLOWERING LOCUS C ) which can be removed after winter in winter-annual Arabidopsis accessions, suggesting the H3K36me3 can be regulated by low temperature. However, whether the H3K36me3 regulates the response to low temperature is still unknown. In this study, we found expression levels of both BnaSDG8.A and BnaSDG8.C were induced after freezing stress treatment in Brassica napus . Simultaneous knock-out of BnaSDG8s decreased the freezing tolerance accompanied with misregulation of stress-responsive genes in Brassica napus . Furthermore, multi-omics analysis revealed that a large number of freezing-responsive genes were misregulated in the bnasdg8s null mutants accompanied with reduced enrichment of H3K36me3 at the corresponding genic loci. In conclusion, our results demonstrated BnaSDG8s can mediate H3k36me3 by activating Ca 2+ / CaM-CAMTA-CBF-COR signal pathway to enhance the freezing tolerance, which may play pivotal role on rapeseed freezing stress response in Brassica napus .

Keywords: Brassica napus, BnaSDG8.A, BnaSDG8.C, H3K36me3, Freezing tolerance