AHAS Trp-574-Leu substitution in Raphanus sativus L.: screening, enzyme activity and fitness cost

BRECCIA, GABRIELA; VERCELLINO, ROMAN B; CANTAMUTTO, MIGUEL; PANDOLFO, CLAUDIO E; PRESOTTO, ALEJANDRO

PEST MANAGEMENT SCIENCE

JOHN WILEY & SONS LTD

Lugar: LOndres; Año: 2018 vol. 74 p. 1600 - 1607

1526-498X

BACKGROUNDFeral radish (Raphanus sativus L.) is a problematic weed that has become resistant to AHAS (acetohydroxyacid synthase) inhibitor herbicides due to the Trp-574-Leu mutation. AHAS gene mutation that causes herbicide resistance may present negative pleiotropic effects on plant fitness. This study reports the effects of the Trp-574-Leu mutation on AHAS activity and reproductive traits of R. sativus.RESULTSEight out of 17 feral radish accessions presented resistant individuals to metsulfuron-methyl from 0.5 to up to more than 90.0 % and all the resistant individuals analyzed showed the Trp-574-Leu mutation. Without herbicide selection, the AHAS activity of a susceptible accession was 3.2-fold higher than the resistant one. The resistant accession was > 9000-fold more resistant to metsulfuron-methyl and imazethapyr than the susceptible one. Under low intraspecific competition during two growing seasons, the AHAS resistant feral radish accessions showed 22 ? 38 and 21 ? 47 % lower seed number and yield per plant than the susceptible ones.CONCLUSIONThis is the first report of fitness cost associated with the AHAS Trp-574-Leu mutation in R. sativus populations. This fitness cost could reduce the frequency of the resistant allele without the herbicide selection.