The widespread use of ALS inhibitors and consequent increase of resistance to this herbicide group prompts new studies on the population dynamics of ALS resistant and susceptible biotypes to check whether the resistance evolution process may be reversed. Theoretically, without herbicide selection pressure to change the R/S allele ratio, an agronomic fitness cost is necessary. This is an important issue tackled by the four-year EU project PURE (Pesticide Use-and-risk Reduction in European farming systems). In order to study the possible fitness cost associated with a broad ALS inhibitors cross-resistance pattern, a population of Echinochloa crus-galli confirmed to be highly cross-resistant to all ALS inhibitors was chosen. Susceptible and resistant plants from the same site were selected and seed stocks with similar genetic background were produced. In the second year a growth analysis field experiment was conducted comparing the two biotypes. Plants were analyzed in competitive and non-competitive situations (e.g. the S target plant was surrounded by plants of the R biotype and vice-versa) at four plant densities. Preliminary experiments suggest that the resistance mechanism involved is target-site mediated. This hypothesis is being confirmed by molecular analyses. Preliminary results of the comparative growth analysis showed very different growth and development of the two biotypes: R seeds germinated later and R plants development was delayed by about one week in comparison with the S ones. S plants produced almost double the number of panicles than the R ones. The effect phased out at high competition level and no differences were observed at 20 plants/m2.
Comparative growth analysis of Echinochloa crus-galli resistant and susceptible to ALS inhibitors
S Panozzo;V Rosan;M Sattin
2013
Abstract
The widespread use of ALS inhibitors and consequent increase of resistance to this herbicide group prompts new studies on the population dynamics of ALS resistant and susceptible biotypes to check whether the resistance evolution process may be reversed. Theoretically, without herbicide selection pressure to change the R/S allele ratio, an agronomic fitness cost is necessary. This is an important issue tackled by the four-year EU project PURE (Pesticide Use-and-risk Reduction in European farming systems). In order to study the possible fitness cost associated with a broad ALS inhibitors cross-resistance pattern, a population of Echinochloa crus-galli confirmed to be highly cross-resistant to all ALS inhibitors was chosen. Susceptible and resistant plants from the same site were selected and seed stocks with similar genetic background were produced. In the second year a growth analysis field experiment was conducted comparing the two biotypes. Plants were analyzed in competitive and non-competitive situations (e.g. the S target plant was surrounded by plants of the R biotype and vice-versa) at four plant densities. Preliminary experiments suggest that the resistance mechanism involved is target-site mediated. This hypothesis is being confirmed by molecular analyses. Preliminary results of the comparative growth analysis showed very different growth and development of the two biotypes: R seeds germinated later and R plants development was delayed by about one week in comparison with the S ones. S plants produced almost double the number of panicles than the R ones. The effect phased out at high competition level and no differences were observed at 20 plants/m2.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
