Effects of wounding and inoculation with Sclerotinia sclerotiorum on isoflavone concentrations in soybean

Abstract

. 2005. Effects of wounding and inoculation with Sclerotinia sclerotiorum on isoflavone concentrations in soybean. Can. J. Plant Sci. 85: 749-760. Isoflavones play an important role in the defense response of soybean to pathogen attack. They are involved in nodulation of legumes and are associated with human health benefits including the prevention of heart disease and cancers. Concentrations of the isoflavones daidzein, genistein, and glycitein, the glucoside conjugates daidzin, genistin and glycitin, the acetyl glucoside conjugates acetyldaidzin, acetylgenistin, and acetylglycitin, and the malonyl glucoside conjugates malonyldaidzin, malonylgenistin, and malonylglycitin were determined in ovendried leaves of 12 soybean cultivars whose stems were (i) non-wounded, non-inoculated (NWNI), (ii) wounded, non-inoculated (WNI), and (iii) wounded and inoculated (WI) with mycelia of Sclerotinia sclerotiorum, the causal fungus of Sclerotinia stem rot of soybean. There were significant differences (P ≤ 0.05) among cultivars in concentrations of isoflavones and their conjugates in all wounding treatments. Concentrations of the aglycones daidzein and genistein were higher (P ≤ 0.05) in WI than in WNI and NWNI plants in all cultivars. Glycitein and its conjugates were detected only in some cultivars in much lower concentrations than daidzein and genistein and their conjugates. Concentrations of total daidzein in the 12 cultivars ranged from 68 to 491, 174 to 781, and 282 to 553 µg g -1 dry weight in NWNI, WNI, and WI plants, respectively. Concentrations of total genistein ranged from 128 to 427, 290 to 840, and 296 to 759 µg g -1 dry weight in NWNI, WNI, and WI plants, respectively. Concentrations of total glycitein ranged from 0 to 44, 0 to 13, and 0 to 24 µg g -1 dry weight in NWNI, WNI, and WI plants, respectively. In NWNI plants, the cultivar Corsoy 79 ranked in the top two (rank 1 = highest concentration, rank 12 = lowest concentration) in concentrations of daidzein and genistein and their conjugates except genistin (ninth rank). In WNI plants, Parker ranked first in concentrations of all conjugates of daidzein and genistein whereas Corsoy 79 consistently ranked in the top four in concentrations of the two isoflavones and their conjugates. In WI plants, Parker ranked first in concentrations of all conjugates of daidzein and genistein except acetyldaidzin (second rank), S19-90 ranked in the top five in concentrations of all conjugates of daidzein and genistein, whereas Corsoy 79 ranked in the top five in concentrations of daidzein and genistein and all of their conjugates. The results from this study suggest that soybean cultivars differ in concentrations of constitutive or induced isoflavones and in their ability to accumulate isoflavones following wounding and/or infection by S. sclerotiorum. For personal use only.

Soybean Cyst Nematode Effects on Soybean Aphid Preference and Performance in the Laboratory

“…These changes can also result in systemic resistance and affect performance and preference of secondary plant attackers (Stout et al 2006). Soybean responds to various stresses by biotic and abiotic factors such as wounding (Wegulo et al 2005), fungi (McDonald and Cahill 1999, Cheong et al 2000, Wegulo et al 2005, Zhang et al 2008, bacteria (Cheong et al 2000), viruses (Kelley et al 2006), nematodes (Ithal et al 2007a,b, Mazarei et al 2007), and aphids (Diaz-Montano 2006. At a cellular level, soybean responds to root infection by soybean cyst nematode with various changes in production of secondary metabolites, such as ßavonoids (Ithal et al 2007b, Jones et al 2007, and in structure of roots (Kim et al 1987).…”

Experimental sink removal induces stress responses, including shifts in amino acid and phenylpropanoid metabolism, in soybean leaves

“…The up-regulation of isoflavone biosynthesis, based on cDNA microarray data, has also been reported for soybean leaves infected with the bacterial pathogen Pseudomonas syringae (Zou et al 2005; Zabala et al 2006), the fungal pathogen Phakospora pachyrhizi (Alvord et al 2007) and the aphid Aphis glycines (Li et al 2008). An increased accumulation of isoflavones was observed in soybean leaves after various experimental treatments, including wounding (Wegulo et al 2005), inoculation with fungi (Morris et al 1991; Wegulo et al 2005), infection with phytopathogenic bacteria or nematodes (Ingham et al 1981; Osman and Fett 1983; Fett 1984; Ithal et al 2007), treatment with abiotic and biotic elicitors (Davis et al 1986), and application of herbicides (Cosio et al 1985). Considering these responses of soybean to experimental stress conditions, our observation of the sink removal-associated shift toward isoflavone accumulation, at the expense of flavones and flavonols, appears to be consistent with the activation of stress responses in soybean leaves.…”

Seeding date, row spacing, and weed effects on soybean isoflavone concentrations and other seed characteristics

“…Kim et al (2005) reported greater isoflavone concentrations in seeds of soybean grown at higher CO 2 levels (i.e., 650 vs. 360 µmol mol -1 of CO 2 ). Finally, stresses such as wounding or pests may also increase soybean isoflavone concentrations (Lozovaya et al 2005;Wegulo et al 2005).…”