The Anaerobic Response of Soybean

The effect of anoxia on roots of soybean (Glycine max [L.] Merr., variety ;Williams') was studied at various levels and the results compared to those from previously studied species. While alcohol dehydrogenase (ADH) activity is induced in a manner similar to other plant species, other aspects of the anaerobic response are unique to soybean. A variety of molecular clones was used to analyze changes in soybean and maize RNA levels. Increased RNA accumulation was observed in both species with a maize ADH clone, while a maize aldolase and one of the two different maize glyceraldehyde-3-phosphate dehydrogenase cDNA clones showed induction only in maize. A maize sucrose synthase 1 clone showed induction in maize but no hybridization to soybean RNA samples. The reduction in the number of anaerobically inducible soybean genes relative to maize is consistent with in vivo and in vitro protein synthesis results. Only four major proteins are labeled during anoxia in soybean, one corresponding to ADH, while maize has been reported to have about 20. In either species, in vitro translation yields similar products with RNA from anaerobic and pre-stress plants, indicative of translational control during anoxia. These results are discussed in relation to the differential tolerance of maize and soybean to anaerobic stress.