The major‐effect quantitative trait locus Cs ARN 6.1 encodes an AAA ATP ase domain‐containing protein that is associated with waterlogging stress tolerance by promoting adventitious root formation

Summary In plants, the formation of hypocotyl‐derived adventitious roots ( AR s) is an important morphological acclimation to waterlogging stress; however, its genetic basis remains fragmentary. Here, through combined use of bulked segregant analysis‐based whole‐genome sequencing, SNP haplotyping and fine genetic mapping, we identified a candidate gene for a major‐effect QTL , ARN 6.1 , that was responsible for waterlogging tolerance due to increased AR formation in the cucumber line Zaoer‐N. Through multiple lines of evidence, we show that Cs ARN 6.1 is the most possible candidate for ARN 6.1 which encodes an AAA ATP ase. The increased formation of AR s under waterlogging in Zaoer‐N could be attributed to a non‐synonymous SNP in the coiled‐coil domain region of this gene. Cs ARN 6.1 increases the number of AR s via its ATP ase activity. Ectopic expression of Cs ARN 6.1 in Arabidopsis resulted in better rooting ability and lateral root development in transgenic plants. Transgenic cucumber expressing the Cs ARN 6.1 Asp allele from Zaoer‐N exhibited a significant increase in number of AR s compared with the wild type expressing the allele from Pepino under waterlogging conditions. Taken together, these data support that the AAA ATP ase gene Cs ARN 6.1 has an important role in increasing cucumber AR formation and waterlogging tolerance.