Schneitz, K. | bioRxiv Science

bioRxiv2018

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 (Ler) accession. Here, we present the study of ZET in Columbia (Col) accession, which not only showed differential expression patterns in comparison to Ler, 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 Ler. In addition, ZETH shows relatively higher expression levels in Col compared to Ler. Our data also reveal compensatory up-regulation of ZETH in Col, but not in Ler, implying it is perhaps dispensable in Ler. However, a novel CRISPR/Cas9-induced zeth allele confirmed that ZETH has residual activity in Ler. 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.

genetics↗

bioRxiv2018

Tissue morphogenesis mediated by the Arabidopsis receptor kinase STRUBBELIG involves a clathrin-dependent process

HighlightThe Arabidopsis receptor kinase STRUBBELIG is internalized by clathrin-mediated endocytosis and affects clathrin-dependent processes in a tissue-dependent manner.\n\nAbstractSignaling mediated by cell surface receptor kinases is central to the coordination of growth patterns during organogenesis. Receptor kinase signaling is in part controlled through endocytosis and subcellular distribution of the respective receptor kinase. For the majority of plant cell surface receptors the underlying trafficking mechanisms are not characterized. In Arabidopsis, tissue morphogenesis relies on the atypical receptor kinase STRUBBELIG (SUB). Here, we approach the endocytic mechanism of SUB. Our data reveal that a functional SUB:EGFP fusion is ubiquitinated in vivo. We further show that plasma membrane-bound SUB:EGFP becomes internalized in a clathrin-dependent fashion. We also find that SUB:EGFP associates with the trans-Golgi network and accumulates in multivesicular bodies and the vacuole. Coimmunoprecipitation experiments reveal that SUB:EGFP and clathrin are present within the same protein complex. Our genetic analysis shows that SUB and CLATHRIN HEAVY CHAIN 2 promote root hair patterning. By contrast, SUB behaves as a negative regulator of a clathrin-dependent process during floral development. Taken together, the data indicate that SUB undergoes clathrin-mediated endocytosis, that this process does not dependent on stimulation of SUB signaling by an exogenous agent, and that SUB genetically interacts with clathrin-dependent pathways in a tissue-specific manner.

plant biology↗