Effect of Spores of Saprophytic Fungi on Phytoalexin Accumulation in Seeds of Frog-Eye Leaf Spot and Stem Canker-Resistant and -Susceptible Soybean (Glycine max L.) Cultivars

Abstract

Two saprophytic fungi (Mucor ramosissimus and Rhizopus sp.) were tested for their ability to induce phytoalexin production by seeds of frog-eye leaf spot and stem canker-resistant and -susceptible soybean (Glycine max L.) cultivars. Only M. ramosissimus was shown to elicit a response and qualitative differences in phytoalexin accumulation were found between the susceptible and resistant cultivars. Glyceollins I, II, and III and glycinol were isolated from the susceptible cultivar, whereas Glyceollins I, II, and III, glycinol, glyceocarpin, genistein, isoformononetin, and N-acetyltyramine accumulated in the resistant cultivar in response to the same fungal elicitor. Genistein was found to be an inducibly formed isoflavonoid instead of a constitutive metabolite in the resistant cultivar, whereas N-acetyltyramine is described for the first time as a soybean phytoalexin. All the compounds, except genistein, showed fungitoxic activity against Cladosporium sphaerospermum. Spectral data of the pterocarpan phytoalexins, genistein, and N-acetyltyramine are also given in this work.

The most abundant polyphenol of soy leaves, coumestrol, displays potent α-glucosidase inhibitory activity

“…Also, in the 13 C NMR spectrum, the chemical shift of C-6a was deshielded to 77.9 ppm. All these data indicated that 7 is a 6a-hydroxypterocapan derivative (Garcez et al, 2000). The presence of two isolated aromatic protons at 7.55 (1H, s) and 6.86 (1H, s) indicate that the A ring of the pterocarpan structure bears substitution at C2.…”

Elicitation studies in cell suspension cultures of Cannabis sativa L.

“…␥-Glutamyl conjugates and tyramine conjugates have been identified as neurotransmitters in insects (Maxwell et al, 1980;Sloley et al, 1990), crustaceans (Battelle and Hart, 2002), mollusks (MacCaman et al, 1985;Karhunen et al, 1993) and mammals (Macfarlane et al, 1989). In plants such as soybean (Garcez et al, 2000), tomato (Zacares et al, 2007), rice (Jang et al, 2004), Lycium chinense (Han et al, 2002;Lee et al, 2004), Chenopodium album (Cutillo et al, 2003), Solanum melongena (Whitaker and Stommel, 2003), Citrus aurantium (Pellati and Benvenuti, 2007), Piper caninum (Ma et al, 2004) and Cyathobasis fructiculosa (Bunge) Aallen (Bahceevli et al, 2005), hydroxycinnamic acid conjugates such as the N-hydroxycinnamic acid amides and amine conjugates such as the phenethylamine alkaloids have been identified as constitutive, induced or overexpressed metabolites of plant defense. Alkaloids, N-hydroxycinnamic acid amides (phenolic amides) and lignans have been identified in cannabis plants (Flores-Sanchez and Verpoorte, 2008a).…”

Purification and characterization of a phytoalexin elicitor from spores of the saprobe Mucor ramosissimus

“…Other saprobe fungi have been described as inducers of phytoalexin accumulation in wild dicotyledonous plants as well as in soybean (Braga et al 1986, Braga & Dietrich 1991, Cordeiro Neto & Dietrich 1992, the inducing activity being comparable to that of pathogenic species (Costa & Dietrich 1996, Garcéz et al 2000. Included among these fungi is Mucor ramosissimus Samutsevitsch, a filamentous Zygomycete commonly found in soil, litter, or on plant surfaces (Ellis 1997).…”

“…Live and autoclaved spore suspensions of M. ramosissimus were shown to be potent inducers of phytoalexin production in detached leaves of these Rubiaceae and in soybean cotyledons (Cordeiro Neto & Dietrich 1992, Goméz et al 1994, Pelicice et al 2000. Garcéz et al (2000) compared the phytoalexin-eliciting activity of this fungus with a saprobe Rhizopus species and observed that only spores of M. ramosissimus were capable of inducing phytoalexin response in soybean cultivars susceptible to frog-eye spot and stem canker disease. In spite of its potent phytoalexin-inducing activity, the elicitor isolated from spores of M. ramosissimus has not yet been characterized.…”