First report of stem blight and leaf spot in horse purslane caused by Gibbago trianthemae in Sinaloa, Mexico

Figures & data

Fig. 1 Trianthema portulacastrum. (a) Lesions on stems; and (b) leaves caused by G. trianthemae under field conditions; (c) non-inoculated; and (d) symptomatic plants 14 days post-inoculation with isolate Gibbt 1 in the greenhouse

Table 1. Morphological characteristics and measurements of asexual structures of ten isolates of Gibbago trianthemae obtained from Trianthema portulacastrum in Sinaloa, Mexico

Isolate	Conidiophore		Septa	Conidia		Ratio L:W	Septa
	Length (μm)	Width (μm)		Length (μm)	Width (μm)		Transverse	Longitudinal
Gibbt 1	32.5–107.0^a	4.5–6.2	1–6	32.5–42.5	17.5–25.0	1.8	2–5	2–5
	63.2^b	5. 0		36.5	20.21
	23.4 ^c	0.3		2.9	2.04
Gibbt 2	35.0–97.5	5.0–5.0	2–7	32.5–42.5	15.0–22.5	1.9	3–5	2–6
	67.3	5. 0		36.6	19.4
	19.1	0. 0		2.8	2.1
	85.0–40.0	5–6.2	1–5	32.5–42.5	17.5–22.5	1.9	3–5	2–6
Gibbt 3	64.1	5.3		37.8	19.6
	14.2	0.5		2.9	1.7
	40.0–97.5	5.0–6.2	1–6	32.5–42.5	17.5–25.0	1.9	2–5	1–6
Gibbt 4	63.6	5.1		38. 0	20.2
	19. 0	0.4		3.2	1.9
	42.5–95.0	4.5–6.2	2–6	32.5–42.5	17.5–22.5	1.9	2–5	1–6
Gibbt 5	72. 0	5. 0		37.6	19.7
	17.7	0.3		3.2	1.8
	47.5–95.0	5.0–6.2	1–7	32.5–42.5	17.5–22.5	1.9	2–5	1–5
Gibbt 6	71.6	5.1		37.8	19.8
	13.5	0.9		3.22	1.81
	45.0–105.0	3.7–5.0	3–7	35.0–42.5	17.5–22.5	1.9	2–5	1–6
Gibbt 7	76.1	4.8		38.1	19.8
	15.2	0.4		3. 0	1.6
	47.5–95.0	3.7–5.0	2–6	32.5–42.5	17.5–22.5	1.9	2–5	1–6
Gibbt 8	72.2	4.8		38. 0	19.8
	19.1	0. 0		3.2	1.6
	35.0–95.0	4.5–6.2	2–5	32.5–42.5	17.5–22.5	1.9	2–4	1–6
Gibbt 9	65.7	5. 0		37.9	19.7
	15.7	0.3		3.7	1.7
	45.0–110.0	4.5–5.0	3–6	32.5–42.5	17.5–22.5	1.9	2–5	1–6
Gibbt 10	77.5	5. 0		37.8	19.6
	18.7	0.1		3.43	1.62
Min/max (10 samples)	32.5–110.0	3.7–6.2	1–7	32.5–42.5	15.0–25.0		2–5	1–6
Mean of 10 samples	69.3	5	4	37.6	19.8		3	3
Standard deviation	23.4	0.4	1.3	3.2	1.9		0.7	1.1

For each isolate, the first line presents the minimum and maximum length (a) of asexual structures, the second line indicates the means (b) for 35 structures of each specimen, and the third line refers to the standard deviation (c) of the data.

Fig. 2 Gibbago trianthemae. (a) Conidiophores and conidia on infected tissue; (b) Colony on PDA; (c) Conidiophore with apical swelling bearing conidium and detached conidia; (d) Geniculated conidiophore. Scale bar = 20 µm

Fig. 3 Neighbour joining tree based on the partial internal transcribed spacer region of Gibbago trianthemae specimens. The tree was constructed with MEGA X (bootstrap = 1000), using the Kimura 2-parameter model and a gamma distribution (+G) to model the among-site rate variation. The corresponding sequence of Neocamarosporium sp. was used as an outgroup. Database accession numbers of the sequences are provided in parentheses. Bootstrap values are given as percentages. Nine isolate sequences obtained in this work were included in the tree and are shown in bold. The scale bar indicates the number of nucleotide substitutions per site

Table 2. Pathogenicity of Gibbago trianthemae in horse purslane plants

Isolate Gibbt 5 Gibbt 6 Gibbt 1 Gibbt 3 Gibbt 2 Gibbt 4 Distilled water control	Disease severity^x 58.0^a* 53.8^a 29.1^b 24.8^b 14.4 ^c 11.1 ^c 0.0^d
CV (%)	24.08

^xThe disease severity in horse purslane based upon the percentage of foliage area diseased (FAD) was assessed 14 days after inoculation.

*Means followed by different letters are significantly different according to Tukey’s test (P < 0.05).