EMS and UV irradiation induce unstable resistance against CAA fungicides in <Emphasis Type="Italic">Bremia lactucae</Emphasis> |
| |
| Authors: | Avia E Rubin Ayelet-Chen Werdiger Mathias Blum Ulrich Gisi Helge Sierotzki Dietrich Hermann Yigal Cohen |
| |
| Institution: | (1) Faculty of Life Sciences, Bar Ilan University, Ramat-Gan, Israel;(2) University of Basel, Basel, Switzerland;(3) Syngenta Crop Protection, Stein, Switzerland; |
| |
| Abstract: | Wild type (WT) field isolates of Bremia lactucae failed to germinate in vitro or infect lettuce leaves in the presence of CAA (carboxylic acid amide) fungicides. Minimal
inhibitory concentrations (MIC) for mandipropamid, dimethomorph, benthiavalicarb and iprovalicarb were 0.005, 0.5, 0.5 and
5 μg ml−1, respectively. Mutagenesis experiments showed that spores exposed to EMS (ethyl methane sulphonate) or UV irradiation (254 nm)
could infect lettuce leaves in the presence of up to 100 μg ml−1 CAA. The proportion of infected leaves relative to the number of spores inoculated (infection frequency) was inversely related
to the concentration of CAA used, ranging between 0 and 160 per 1 × 106 spores. Resistant mutants (RM) lost their resistance within 1–14 reproduction cycles on CAA-treated plants. Crosses were
made between RMxWT isolates and RMxRM isolates with an attempt to obtain stable homozygous resistant off-springs. Such crosses
yielded few resistant but unstable progeny isolates. Mutagenic treatments given to hybrid isolates also failed to produce
stable resistance. Previous gene sequencing data showed that stable resistance to CAAs is based on a single SNP in the cellulose synthase 3 (CesA3) gene of Plasmopara viticola. Therefore, we sequenced a 582 bp DNA fragment of Ces3A of WT, RM and hybrid isolates of B.lactucae. No mutation in this gene fragment was found. We conclude that mutagenic agents like EMS or UV may induce resistance to CAA
in Bremia lactucae but this resistance is not stable and not linked to mutations in CesA3 gene. |
| |
| Keywords: | |
| 本文献已被 SpringerLink 等数据库收录！ |
|
