Fusarium spp. associated with Chenopodium quinoa crops in Colombia

Abstract

Quinoa is a plant commonly-resistance to adverse biotic and abiotic factors. However, this crop can be affected by phytopathogenic fungi. There is a lack of knowledge about the fungi associated with quinoa plants in Colombia. Through morphological and molecular identification in this study were identified four Fusarium species associated with quinoa crops: Fusarium oxysporum, Fusarium graminearum, Fusarium equiseti, and Fusarium culmorum. For this, we collected samples of panicles, leaf tissue, root tissue, and soil for isolation of different isolates of Fusarium. We performed a pathogenicity test of the fungi strains, under greenhouse conditions to evaluate the pathogenicity in seedlings of the Piartal cultivar with two inoculation methods. First inoculating the stem through a nodal wound or second inoculating the abaxial face with a brush. The results indicate the presence of four species with both molecular markers, phylogenetically distributed in these groups. The four species turned out to be pathogenic but with different degrees of virulence with significant differences between F. graminearum and F. oxysporum depending on the inoculation method. This is the first report on the presence of Fusarium species isolated from Quinoa in Colombia.

Figure 1

Macro and microscopic characteristics of the Fusarium complex associated with quinoa crops. On top the growth of the colonies of the 4 species F. culmorum, F. graminearum F. oxysporum and F. equiseti in PDA culture media after 7 days of incubation at 28 °C, at back side (right) and front side (left). Down the microscopic structures obtained after 14 days of incubation in SNA at 25 °C, and 12-h light/dark photoperiod. Scale of 40 × magnification.

Figure 2

Phylogenetic tree of Fusarium isolates in quinoa, based on neighbor-joining analysis of the EF1-α gene. Bootstrap values are from a bootstrap test of 1000 replicates. NR_172378.1 corresponds to the F. torreyae outgroup.

Figure 3

Phylogenetic tree of Fusarium isolates in quinoa, based on neighbor-joining analysis of the ITS gene. Bootstrap values are from a bootstrap test of 1000 replicates. OM117609.1 corresponds to F. torreyae outgroup.

Figure 4

Lesions observed in the field crops that presented growth of Fusarium spp. (a) Leaves collected with different degrees of affectation. (b) The lesions corresponding to Fusarium spp. were determined by the growth of the mycelium, after seven days of incubation.

Figure 5

Lesions induced by Fusarium spp. observed in leaves inoculated with isolated mycelia. Chlorotic lesions are observed on leaves incubated in a humid chamber. The photographic record corresponds to after five days post inoculation.

Figure 6

Symptomatology induced by F. culmorum, F. equiseti, F. graminearum and F. oxysporum in Piartal cv seedlings inoculated by brush method. The symptomatology is observed on the plant (above) and its detail in leaves (below). The control corresponds to plants without fungal inoculum. Symptoms were observed after 10 days of inoculation.

Figure 7

Symptomatology induced by F. graminearum, F. oxysporum, F. culmorum and F. equiseti in Piartal cv seedlings inoculated by wound method. The symptomatology is observed on the plant (above) and its detail in leaves (below). The control corresponds to leaves without fungal inoculum. Symptoms were observed after 90 days of inoculation.

Figure 8

Disease Incidence of F. equiseti, F. oxysporum, F. graminearum, F. culmorum in quinoa seedlings. The data are expressed as the mean with confidence interval using Student's T-test (p < 0.05). Letters indicated statistically significant differences between brush and wound inoculation, (a) for F. equiseti, (b,c) for F. oxysporum, (d,e) for F. graminearum and (f) for F. culmorum.

Figure 9

Affectation of root development induced by Fusarium spp. in 10-day-old quinoa seedlings. Development of seedlings of the Piartal cultivar in soils inoculated with F. culmorum, F. equiseti, F. graminearum and F. oxysporum, under greenhouse conditions. It is observed that the root development was affected by the treatments.

Figure 10

Average total length and root length of seedlings inoculated with Fusarium spp. under greenhouse conditions. The letters indicate significant differences between the control and the treatments (a, b) for root length and (c, d) for total length. The data are expressed as the mean with confidence interval using Student's T-test (p < 0.05).