Determine Phytoene Desaturase Gene Copy Number in Hydrilla verticillata

Abstract

Hydrilla verticillata is an invasive aquatic weed in the United States (U.S.) that has recently developed resistance to the herbicide fluridone. In this study, we utilized genome walking and quantitative real-time PCR to investigate the phytoene desaturase (PDS) gene copy number of hydrilla samples with different ploidy levels. We asked 1) if copy number simply corresponds to the ploidy level, and 2) if there is increased PDS copy number in resistant populations due to gene duplication. Using qPCR and microsatellite loci to compare PDS copy number between diploid, triploid and tetraploid samples, we found that diploid hydrilla from Africa showed higher PDS copy number than triploid populations from the U.S. The results also indicated that there was no significant difference in PDS gene copy numbers between the fluridone-resistant and -susceptible triploid populations. Our study suggests that PDS amplification may not be a mechanism responsible for fluridone resistance in hydrilla.