A cosegregation analysis of zinc (Zn) accumulation and Zn tolerance in the Zn hyperaccumulator Thlaspi caerulescens.

• To analyse the relation between zinc (Zn) accumulation and Zn tolerance in the Zn hyperaccumulator, Thlaspi caerulescens, a cross was made between a plant from a nonmetallicolous population (LE: high accumulation, low tolerance) and one from a calamine population (LC: low accumulation, high tolerance). • More or less homogeneous

Evolution of herbicide resistance in weeds: initial frequency of target site-based resistance to acetolactate synthase-inhibiting herbicides in Lolium rigidum

© 2002 Nature Publishing GroupThe frequency of individuals resistant to two acetolactate synthase (ALS)-inhibiting herbicides in three previously untreated populations of Lolium rigidum was determined. The frequency of individuals resistant to the sulfonylurea herbicide sulfometuron-methyl varied from 2.2 x 10⁻⁵ to 1.2 x 10⁻⁴ and the frequency of individuals resistant to the imidazolinone herbicide imazapyr varied from 1 x 10⁻⁵ to 5.8 x 10⁻⁵ depending on the population. Application of sulfometuron-methyl selected individuals with a herbicide-insensitive ALS, which was also cross-resistant to imazapyr. The high initial frequency of individuals resistant to ALS-inhibiting herbicides in L. rigidumpopulations never previously exposed to these herbicides helps explain the rapid evolution of herbicide resistance in this species once ALS-inhibiting herbicides were used