Root exudates associated with the resistance of four chickpea cultivars (Cicer arietinum) to two races of Fusarium oxysporum f.sp. ciceri

Abstract

The germination of race 1 spores of Fusarium oxysporum f. sp. ciceri was significantly inhibited by the root exudate of the wilt‐resistant chickpea cvs CPS1 and WR315 compared to untreated spores and spores treated with root exudates from susceptible cultivars. The effect was concentration dependent, such that the exudate from 1 g of root in 2 ml of water almost completely inhibited spore germination, whereas the exudate from 1 g of root in 20 ml water did not do so. The inhibitory effects of the active exudates were negated when the apolar components of the exudates were removed by extraction with ethyl acetate. The root exudates of the susceptible cv. JG62 and the late wilting cv. H208 did not inhibit germination. The hyphal growth of germinated spores was also strongly inhibited by the concentrated exudates of CPS1 and WR315, and diluted exudates were less potent. The highest concentration of the exudate of the susceptible cv. JG62 showed some inhibition of hyphal growth, whereas none of the exudates of H208 were found to contain any antifungal activity. The effect of the exudates on the spores of race 2 was similar to that reported for race 1, except that the water‐soluble components of the crude root exudate of WR315 after ethyl acetate extraction were also found to inhibit germination significantly. Overall, the spores of race 2 appeared to be more susceptible to the effects of the exudates. The ethyl acetate fractions of the root exudates of CPS1 and WR315 strongly inhibited germination and hyphal growth of both race 1 and race 2, the effect being concentration dependent. The results suggest that the resistance of chickpeas to vascular wilt depends, at least in part, upon the antifungal activity of the root exudates. Differences in the expression of resistance in the field could depend upon the concentration or rate of production of constitutive antifungal components by the root.

The use of GFP-transformed isolates to study infection of banana with Fusarium oxysporum f. sp. cubense race 4

“…After 15 days, roots were weighted and the exudate solution was collected. The exudate solution was extracted twice in a separating funnel with an equal volume of ethyl acetate (Stevenson et al 1995). The apolar fraction in ethyl acetate was collected and evaporated to dryness with a rotary evaporator (RE-3000B, Analytical Instrument Co., Ltd. Shanghai Jinpeng), and then dissolved in methanol to give a solution equivalent to 1 g root/ml.…”

“…The banana plantlets were first grown in plastic cups filled with 200 ml of sterile distilled water at room temperature (Stevenson et al 1995). Each cup contained a single plantlet, and five plantlets per cultivar were included in the experiment.…”

Microconidia germination of the tomato pathogenFusarium oxysporumin the presence of root exudates

“…The plants were inserted in a beaker containing sterile distilled water, such that the roots were completely submerged, and placed in a plant growth chamber for 24 h at 248C. Thereafter, the plants were removed from the beaker and the resulting exudate solution was adjusted with sterile distilled water to 1 g root fresh weight per 20 ml exudate solution (w/v) (Stevenson et al 1995, Pinior et al 1999. In order to get additional information on the plant material besides the root fresh weight also the fresh weight of the shoot, the phenological growth stage (according to Anonymous 1997) and the pH value of the root exudate were determined.…”

Cropping systems strategy for effective management of Fusarium wilt in safflower

“…Mandal and Sinha (1991) reported that crop cultivars resistant or tolerant to fungal pathogens produce higher quantities of concentrated exudates to thwart pathogen invasion, while the susceptible genotypes either do not produce root exudates toxic to fungal growth or produce compounds that stimulate pathogen growth. A number of in vitro (Bagwan, 2010;Stevenson et al, 1995), and field studies (Hao et al, 2007) reported that different crops discharge specific root exudates and antifungal compunds, such as phenolics, photoalexins, and allelochemicals, into the rhizosphere.…”