Regulation by sulfhydryl groups of glyceollin accumulation in soybean hypocotyls

Abstract

Hypocotyls of 5-d-old etiolated soybean seedlings (Glycine max (L.) Merr. cv. Altona) were treated with (a) dithiothreitol (DTT) or one of the sulfhydryl-binding reagents N-ethylmaleimide (NEM), p-hydroxymercuribenzoate (PMB) und p-chloromercuribenzene sulfonic acid (PMBS), (b) one of the sulfhydryl reagents in combination with DTT, (c) sulfhydryl reagent subsequent to treatment with DTT, and (d) PMBS followed by DTT. Glyceollin was extracted 24 and 48 h after initiation of treatment. The order of decreasing glyceollin-eliciting activity was PMBS≫DTT>PMB≧NEM. Elicitor effectiveness of sulfhydryl reagents and their reactivity with either L-cysteine or sulfhydryl groups in soybean hypocotyls were not strictly correlated. Mixtures of sulfhydryl reagent and DTT, pretreatment of hypocotyls with DTT and subsequent application of either PMB or PMBS, as well as application of PMBS prior to DTT induced less glyceollin than sulfhydryl reagents alone. In contrast, such pretreatment did not appreciably alter glyceollin accumulation elicited by NEM. The results indicate that glyceollin synthesis can be regulated by interaction with sulfhydryl groups located mainly at the outer surface of the plasmalemma.

Signaling in Soybean Phenylpropanoid Responses (Dissection of Primary, Secondary, and Conditioning Effects of Light, Wounding, and Elicitor Treatments)

“…A wide range of organic and inorganic sulfhydrylmodifying reagents possess elicitor activity in various plant species (see, for example, Yoshikawa, 1978;Ingham et al, 1981;Osman and Fett, 1983;Stossel, 1984), although the effects of these molecules on elicitation in soybean appear to be indirect . Due to these activities, the biological sulfhydryl molecule glutathione has also been investigated as a potential defense-related signal.…”

Glutathione Causes a Massive and Selective Induction of Plant Defense Genes

“…Moreover, certain sulfhydryl reagents stimulate the production of phytoalexins and the activation of other defense responses associated with the expression of disease resistance (11,24). Taken together these observations suggest that glutathione may play a role in mediating the response of plant cells to biological as well as physical stresses.…”

“…Moreover, certain sulfhydryl reagents stimulate the production of phytoalexins and the activation of other defense responses associated with the expression of disease resistance (11,24). Taken …”

“…Thus, it is possible that in bean cells GSH may be able to cleave such linkages in an elicitor receptor and thus initiate defense gene activation in the absence of elicitor without implying a physiological role for GSH in this signal transduction pathway. Interestingly, a number of sulfhydryl reagents including p-chloromercuribenzoic acid and p-chloromercuribenzene sulfonic acid elicit synthesis of glyceollin in soybean hypocotyls and medicarpin in Ladino clover callus (11,24).…”

Inducible Phytoalexins in Juvenile Soybean Genotypes Predict Soybean Looper Resistance in the Fully Developed Plants

“…glyceollin) accumulation in fully developed soybean plants (15,16). Stossel (24,25) also showed that sulfhydrylbinding reagents could induce glyceollin accumulation in soybean hypocotyls. Glyceollin is one of several isoflavonoids in legumes that have been confirmed as contributors to the plant's antixenosis and antibiosis to insects (5,6,20,22).…”