Asymmetric redundancy of ZERZAUST and ZERZAUST HOMOLOG in different accessions of Arabidopsis thaliana

Divergence among duplicate genes is one of the important sources of evolutionary innovation. But, the contribution of duplicate divergence to variation in Arabidopsis accessions is sparsely known. Recently, we studied the role of a cell wall localized protein, ZERZAUST (ZET), in Landsberg erecta (L er ) accession. Here, we present the study of ZET in Columbia (Col) accession, which not only showed differential expression patterns in comparison to L er , but also revealed its close homolog, ZERZAUST HOMOLOG (ZETH) . Although, genetic analysis implied redundancy, expression analysis revealed divergence, with ZETH showing minimal expression in both Col and L er . In addition, ZETH shows relatively higher expression levels in Col compared to L er . Our data also reveal compensatory up-regulation of ZETH in Col, but not in L er , implying it is perhaps dispensable in L er . However, a novel CRISPR/Cas9-induced zeth allele confirmed that ZETH has residual activity in L er . The results provide genetic evidence for accession-specific differences in compensation mechanism and asymmetric gene contribution. Thus, our work reveals a novel example for how weakly expressed homologs contribute to diversity among accessions.