Field and laboratory studies were conducted to determine if differences existed in pinto bean varietal tolerance to postemergence application of imazethapyr under field conditions; if differences in tolerance were due to differential acetolactate synthase enzyme sensitivity or differences in 14C-imazethapyr absorption, translocation, and metabolism; and the heritability of imazethapyr tolerance in pinto bean. All rates of imazethapyr injured Olathe, Sierra, UI-114, P89405, Aztec, and P90570 pinto bean varieties 7 d after treatment in 1991 and 1992, except 53 g ai ha−1 of imazethapyr applied to Sierra pinto bean in 1991. Olathe was injured more than other varieties in 1991, and physiological maturity of Olathe was delayed more than Sierra in 1991 and 1992. Seed yields of all varieties were not reduced in 1991, and only P90570 had reduced seed yields from 53 g ha−1 of imazethapyr in 1992. Differential sensitivity of the acetolactate synthase enzyme to imazethapyr was not the mechanism of differential varietal response. Olathe pinto bean absorbed and translocated 1.4 and 1.3 times more 14C-imazethapyr, respectively, than Sierra pinto bean 24 h after application. No differences in 14C-imazethapyr metabolism were detected between Olathe and Sierra pinto bean. Broad heritability of imazethapyr tolerance in pinto bean was calculated to be 0.85. The number of genes controlling the inheritance of imazethapyr tolerance in pinto bean was greater than one.

Pulses are grain legumes that have sustained the civilisations of the world throughout their development; yet this staple food crop has fallen into disuse, particularly in Westernised societies, and decreased consumption parallels increased prevalence of CVD. The objective of the present study was to identify mechanisms that account for the cardioprotective activity of dry bean (Phaseolus vulgaris L.), one of the four primary pulse crops, which is widely produced and consumed globally. Laboratory assays that can be used for in vivo screening of dry beans and other pulses to identify those with the greatest potential to benefit human health are also reported. Sprague–Dawley rats and a diet-induced obesity model in C57Bl/6 mice were used to assess the effect of cooked dry bean incorporated into a purified diet formulation on plasma lipids and hepatic proteins involved in the regulation of lipid biosynthesis. In both animal species, short-term feeding of a bean-containing diet reduced plasma total cholesterol and LDL-cholesterol without affecting HDL-cholesterol or total TAG. Mechanisms associated with cholesterol catabolism and excretion are the likely targets of the bean effect. Unexpectedly, bean-fed obese mice experienced weight loss as well as an improved plasma lipid profile within a 12 d time frame. These findings support the use of short-term (7–14 d) assays to investigate mechanisms that account for the cardioprotective and weight regulatory effects of dry bean and to screen dry bean germplasm resources for types of bean with high protective activity. These same assays can be used to identify the bioactive components of bean that account for the observed effects.