By BLAST searching a large expressed sequence tag database for glutathione S-transferase (GST) sequences we have identified 25 soybean (Glycine max) and 42 maize (Zea mays) clones and obtained accurate full-length GST sequences. These clones probably represent the majority of members of the GST multigene family in these species. Plant GSTs are divided according to sequence similarity into three categories: types I, II, and III. Among these GSTs only the active site serine, as well as another serine and arginine in or near the “G-site” are conserved throughout. Type III GSTs have four conserved sequence patches mapping to distinct structural features. Expression analysis reveals the distribution of GSTs in different tissues and treatments: Maize GSTI is overall the most highly expressed in maize, whereas the previously unknown GmGST 8 is most abundant in soybean. Using DNA microarray analysis we observed increased expression among the type III GSTs after inducer treatment of maize shoots, with different genes responding to different treatments. Protein activity for a subset of GSTs varied widely with seven substrates, and any GST exhibiting greater than marginal activity with chloro-2,4 dinitrobenzene activity also exhibited significant activity with all other substrates, suggesting broad individual enzyme substrate specificity.
The fate of 14C-labeled rimsulfuron in aqueous and soil environments was examined. Hydrolysis was first-order, pH-dependent, and accelerated at higher temperatures. Rimsulfuron degraded rapidly in pH 5, 7, and 9 buffer solutions (25 °C) with half-lives of 4.7, 7.2, and 0.4 days, respectively, primarily through contraction of the sulfonylurea bridge. Soil metabolism studies also showed rapid decomposition by bridge contraction with half-lives of 24.5 (laboratory) and 5.7 (field) days. The degradation rate and metabolic pathway did not change when aqueous solutions (pH 7 or 9) or soil was kept in the dark or exposed to light. A faster degradation rate in light-exposed pH 5 aqueous solution was observed. Rimsulfuron was moderately adsorbed on soils with high levels of clay or organic matter. Although soil TLC suggested rimsulfuron could be mobile, minimal mobility was observed under field conditions. Rimsulfuron residues (>0.01 ppm) were not observed in rotational crops grown in rimsulfuron-treated soil.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.