ARABIDOPSIS HOMOLOG OF THRITORAX impact the lateral root development by epigenetic regulation of targets involved in root system architecture.
The chemical modifications of histones between others process are important to modify the chromatin structure and permit the access to DNA. The ARABIDOPSIS HOMOLOG OF TRITHORAX1 (ATX1/SDG27) is a known regulator of floral development which encodes a histone methyltransferase (H3K4me). ATX1 is directly involved in the H3K4 trimethylation which is associated with maintenance of transcriptionally active chromatin state. To study the ATX1 role in lateral root development, we performed a root phenotypic analysis of atx1setm mutant, and the transcriptome profiling (using RNA-seq approach). The atx1setm mutant express the catalytically inactive form of the ATX1 protein (that maintains its structural integrity) in the atx1-1 (null mutant) background. Here, we showed that the primary root and lateral root (LR) primordium (LRP) development in the atx1setm mutant are abnormal, and the phenotype is stronger compared to the atx1-1 mutant. We identified ATX1-activated genes involved in the LR development like PEROXIDASE35 (PER35), AGAMOUS LIKE14 (AGL14), HOMEOBOX PROTEIN 21 (ATHB21), KIDARI (KDR) and USUALLY MULTIPLE ACIDS MOVE IN AND OUT TRANSPORTERS 20 (UMAMIT20). Here, we studied PEROXIDASE 35 gene whose expression is promoted by ATX1 activity. Interestingly, in the per35 mutant the primary root growth was greater compared to Wt and the LRP morphogenesis was abnormal with a phenotype like that found in atx1setm mutant. The data suggest that PER35 gene is a new player related to lateral root primordium morphogenesis in Arabidopsis thaliana. Overall design: RNA-seq was done for whole roots of two biological replicates from the atx1setm and the Wt genotype (10 days-post-germination seedlings). Two biological replicates per genotype