AUTHOR=Atanasov Kostadin E. , Barboza-Barquero Luis , Tiburcio Antonio F. , Alcázar Rubén 

TITLE=Genome Wide Association Mapping for the Tolerance to the Polyamine Oxidase Inhibitor Guazatine in Arabidopsis thaliana

JOURNAL=Frontiers in Plant Science

VOLUME=7

YEAR=2016

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2016.00401

DOI=10.3389/fpls.2016.00401

ISSN=1664-462X

ABSTRACT=<p>Guazatine is a potent inhibitor of polyamine oxidase (PAO) activity. In agriculture, guazatine is used as non-systemic contact fungicide efficient in the protection of cereals and citrus fruits against disease. The composition of guazatine is complex, mainly constituted by a mixture of synthetic guanidated polyamines (polyaminoguanidines). Here, we have studied the effects from exposure to guazatine in the weed <italic>Arabidopsis thaliana</italic>. We report that micromolar concentrations of guazatine are sufficient to inhibit growth of <italic>Arabidopsis</italic> seedlings and induce chlorosis, whereas germination is barely affected. We observed the occurrence of quantitative variation in the response to guazatine between 107 randomly chosen <italic>Arabidopsis</italic> accessions. This enabled us to undertake genome-wide association (GWA) mapping that identified a locus on chromosome one associated with guazatine tolerance. <italic>CHLOROPHYLLASE 1</italic> (<italic>CLH1</italic>) within this locus was studied as candidate gene, together with its paralog <italic>(CLH2)</italic>. The analysis of independent <italic>clh1-2, clh1-3, clh2-3, clh2-2</italic>, and double <italic>clh1-2 clh2-3</italic> mutant alleles indicated that <italic>CLH1</italic> and/or <italic>CLH2</italic> loss-of-function or expression down-regulation promote guazatine tolerance in <italic>Arabidopsis</italic>. We report a natural mechanism by which <italic>Arabidopsis</italic> populations can overcome toxicity by the fungicide guazatine.</p>