The DELAYED ABAXIAL TRICHOMES (DAB) Helitron has dual functions in vegetative and pollen development in Arabidopsis thaliana

Transposons drive genetic diversity and evolution by altering the genomic landscape over time. Here, we describe DELAYED-ABAXIAL TRICHOMES (DAB), a novel Helitron/RC transposable element in Arabidopsis thaliana that has vital role in vegetative phase change and gametogenesis. A genome-wide association study (GWAS) for the timing of abaxial trichome development (an adult leaf trait) in A. thaliana revealed a conserved haplotype of SNPs within DAB that delays abaxial trichome production. CRISPR-Cas9-induced deletions of DAB are gametophytic pollen-lethal, indicating that this locus is also required for pollen production. DAB produces 24-nucelotide siRNAs with sequence complementarity to genes involved in embryogenesis, gametogenesis, and seed development. DAB also impacts the expression of ARGONAUTE genes, genes involved in RNA-directed DNA-methylation, as well as genes in several key genetic pathways. These results suggest that DAB has multiple functions in embryonic, vegetative and reproductive development.