The Anaerobic Response of Soybean

Abstract

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. assure survival when anoxia prevents mitochondrial activity. Studies at the molecular level have helped define the mechanism of the anaerobic induction of these genes. Lin and Key (15) reported that polysomes exhibit rapid dissociation during anaerobic treatment of soybean. This pioneering study on the effect of anoxia on translation in plants was followed by studies in maize which led to the conclusion that anoxia induces the transcription and accumulation of a new set of mRNAs. Although pre-stress mRNAs are generally still present, only genes that show an increase in transcript accumulation during anoxia are translated, yielding the ANPs. Among the -20 ANPs of maize is ADH (23) as well as other enzymes related to glycolysis such as sucrose synthase (25), phosphoglucoisomerase, aldolase, and pyruvate decarboxylase (cf 6).The present study was undertaken to determine if translation is selectively altered in anaerobically treated soybean seedlings, rather than the observed destruction of polysomes (15) being solely the result of a nonselective reduction in protein synthesis. Additionally, molecular clones related to anaerobically induced mRNAs of maize were used as probes to determine if there is a pattern of mRNA accumulation in soybean similar to that seen in anaerobically treated maize (6,23,25). Our results show that anoxic treatment of soybean seedlings induces the accumulation of ADH mRNA, selective synthesis of ADH protein, and accumulation of enzyme activity. In contrast to maize, the pattern of anaerobic protein synthesis is simpler in soybean and may be at least partially explained by the lack of mRNA accumulation for other genes related to glycolysis. We also compare the flood tolerance of maize and soybean seedlings, and find soybean to be more sensitive to flooding, which may be a result of its simpler molecular response to anaerobic stress. MATERIALS AND METHODS Seed GerminationSeeds of soybean Glycine max (L.) Merr

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The Role of Sugars, Hexokinase, and Sucrose Synthase in the Determination of Hypoxically Induced Tolerance to Anoxia in Tomato Roots

“…From molecular mass considerations and induction characteristics, it is tempting to speculate that these may include SS (92.4-kD subunit molecular m a s reported for tomato SS by Wang et al [1993]) and PDC (62-and 64-kD subunit masses reported for rice PDC by Rivoal et al [1990]). It is also noteworthy that the protein profile is strikingly similar in complexity to that of maize primary roots labeled under anoxia (Sachs et al, 1980) and very different from the simple profile of soybean (Russell et al, 1990).…”

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