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Figure 1

From: Transcriptomic and metabolomic analyses identify a role for chlorophyll catabolism and phytoalexin during Medicago nonhost resistance against Asian soybean rust

Figure 1

Disease and resistance phenotypes of soybean (Glycine max) and M. truncatula leaves inoculated with P. pachyrhizi. (A) Epifluorescence micrographs of P. pachyrhizi on abaxial leaf surfaces of soybean (G. max cv. Williams) and M. truncatula wild-type R108 at 6, 12, 24 and 48 hours post-inoculation (hpi). The 4-week-old soybean and M. truncatula plants were spray-inoculated with 1 × 105 spores/ml (0.001% Tween 20) of P. pachyrhizi using an artist air-brush. For fluorescence microscopy, fungal mycelia in the inoculated leaves were stained with 10 μg/mL WGA-Alexa Fluor 488 for 20 min at room temperature. After washing with PBS, the leaves were observed using an epifluorescence microscope. (B) Quantification of germination and pre-infection structures of P. pachyrhizi on abaxial leaf surfaces of soybean (G. max cv. Williams) and M. truncatula wild-type R108 at 72 hpi. Four-week-old soybean and M. truncatula plants were spot-inoculated with 10 μl of 1 × 104 spores/ml (0.001% Tween 20) of P. pachyrhizi. The formation of pre-infection structures was counted from 20 random fields on three independent leaves. The number of dead autofluorescing epidermal cells resulting from direct penetration of P. pachyrhizi were counted from 20 random fields per each inoculated site and are used to calculate the percentage of penetration. The experiments were repeated at least 3 times. (C) Disease symptom development of soybean (G. max cv. Williams) and M. truncatula abaxial leaf surfaces inoculated with P. pachyrhizi at 1, 2, 7 and 12 days post-inoculation (dpi). Four-week old soybean and M. truncatula plants were spot-inoculated on the adaxial side of the leaf with 10 μl of 1 × 104 spores/ml (0.001% Tween 20) of P. pachyrhizi. The inoculated leaves were maintained in a dew chamber for 24 hrs with 100% humidity maintained at 19 °C; 0-hrs-light/24-hrs-dark cycle. The leaves were then transferred to a growth chamber (22 °C/19 °C with 12 hrs-light/12 hrs-dark cycle) and incubated further to allow symptom development. Photographs were taken at time points indicated.

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