Figure 1.
Pattern of stem rust severities on Brachypodium inbred lines inoculated with urediniospores of P. graminis f. sp. lolii (Pg-lo), P. graminis f. sp. phlei-pratensis (Pg-pp) or P. graminis f. sp. tritici (Pg-tr).
Data were collected at 12 days post-inoculation. Bar height represents the mean of total number of sporulating lesions per plant across two trials. Error bars indicate standard error of the mean for each treatment, pooled across trials. Results from statistical analysis are shown in Table 1.
Table 1.
Disease severity of Brachypodium inbred lines challenged with P. graminis f. sp. lolii (Pg-lo), P. graminis f. sp. phlei-pratensis (Pg-pp) and P. graminis f. sp. tritici (Pg-tr)*.
Figure 2.
Variation of symptom phenotypes induced by the different stem rust formae speciales.
(A) Close-up image of the sporulating lesions developed in the different Brachypodium inbred lines and natural hosts inoculated with fungal isolates P. graminis f. sp. tritici (Pg-tr), P. graminis f. sp. lolii (Pg-lo), and P. graminis f. sp. phlei-pratensis (Pg-pp). (B) Time of symptom appearance in Brachypodium inbred line Bd1-1 according to fungal isolates. Scale bar indicates 5 cm.
Figure 3.
Early events in the infection of Brachypodium inbred line Bd1-1 by Puccinia graminis formae speciales.
Fluorescence micrographs of longitudinal leaf sections show the fungal penetration sites and formation of infection structures according to time in hours post-inoculation (left side). The isolates P. graminis f. sp. tritici (Pg-tr), P. graminis f. sp. lolii (Pg-lo), and P. graminis f. sp. phlei-pratensis (Pg-pp) used for inoculation are indicated at the top of the figure. Fungal tissue was stained with Uvitex 2B (chitin specific) which exhibits blue fluorescence under UV-light. Structures are labeled as follows: u, urediniospore; g, germ tube; a, appressorium; s, leaf stoma; i, primary infection hyphae; v, substomatal vesicle; h, haustorium. Panels D, E, G and H show the formation of callose papillae below fungal penetration sites. Scale bar in panel L indicates 20 µm.
Figure 4.
Time course of the differentiation of infection structures by Puccinia graminis formae speciales in Brachypodium inbred line Bd1-1.
Top panel shows P. graminis f. sp. lolii (Pg-lo), middle panel shows P. graminis f. sp. phlei-pratensis (Pg-pp), and bottom panel shows P. graminis f. sp. tritici (Pg-tr). The percentage of germinated urediniospores that formed an appressorium (a) at the end of the germ tube is indicated by solid white bars. The percentage of germinated urediniospores that reached the formation of either a penetration peg (p), a substomatal vesicle (v) and/or primary infection hyphae (i) are indicated by the white and grey striped bars. The percentage of germinated urediniospores that reached the stage of haustorium mother cell or primary haustorium (h) is shown by the gray solid bars. The percentage of germinated urediniospores that established a colony (c) is shown by black solid bars. Bar heights indicate the averages of total percentages, and error bars represent standard deviation.