Requerimientos lumínicos para la germinación de Lolium rigidum (ryegrass anual) asociado a distintas mutaciones de resistencia a herbicidas inhibidores de ACCasa

PONCE, DANIELA; DÉLYE, CHRISTOPHE ; POWLES, SB; VILA AIUB, MM

Congreso; XXII Congreso Latinoamericano de Malezas y I Congreso Argentino de Malezas; 2015

Herbicide resistance alleles may have associated pleiotropic effects on fitness of resistant weeds. Quantifying these effects enables a better prediction of herbicide resistance dynamics and may help to design herbicide resistance management strategies. The effect of light environment on the dormancy release in herbicide resistant Lolium rigidum was investigated with the Ile-1781-Leu mutation in the ACCase gene (SLR31 population). Seeds with this mutation show significant high dormancy in dark conditions. An experiment was conducted to evaluate the light requirement associated with the Ile-1781-Leu, Ile-2041-Asp, Asp-2078-Gly and Cys-2088-Arg mutations from other L. rigidum populations. For each mutation, germination was quantified in susceptible homozygous (SS), resistant heterozygous (RS/SR) and resistant homozygous (RR). The seeds were incubated in Petri dishes with agar-water (0.8% w/v) in fluctuating temperature (25/15°C) with a 12 h period and subjected to three light treatments: 14 days of light (DL), 14 days of dark (DD), and dark for 14 days followed by exposure to light of 14 days (DD+DL). Regardless of the mutation and genotype, higher germination was observed in the DD+DL environment. Dark-stratification promoted germination of dormant L. rigidum seeds when exposed to light. The absence of light (DD) markedly inhibited the germination and seedling emergence in all mutations and genotypes. Furthermore, heterozygous genotypes SR/RS of the specific Ile-1781-Leu, Asp-2078-Gly and Cys-2088-Arg mutations showed lower germination compared to RR and SS genotypes in the DL and DD+DL. This study demonstrated that specific target site ACCase mutations and genotypes show differential germination responses to light environments. Heterozygous genotypes for some specific ACCase mutations seem to show higher seed dormancy and less sensitivity to dark stratification.