Effects of fungal endophyte infection on soil properties and microbial communities in the host grass habitat

doi:10.3724/SP.J.1258.2014.00006

Abstract

Abstract:

Aims Leymus chinensis is a dominant grass native to the mid-eastern Inner Mongolia Steppe. The plants of this species are sometimes heavily infected with fungal endophytes that produce alkaloids, which in turn affect insect herbivory, plant production, and litter decomposition. Our objective was to investigate the effects of the L. chinensis-endophyte association on soil properties and soil microbial communities in field and pot experiments.
Methods We concurrently conducted a field and a pot experiment. The soil total carbon (C) and nitrogen (N) were analyzed with an Elemental Analyzer, and C mineralization was determined by using a soil incubation test over a 30-day period. Soil microbial biomass and community composition were assayed by using phospholipid fatty acid (PLFA) technique.
Important findings In the field experiment, where L. chinensis plants had grown for longer time and there was litter decomposition, fungal endophyte infection significantly increased soil N content, the initial C mineralization rate, the C mineralization during the first three days, and the accumulative C mineralization during the 30-day soil incubation. In the pot experiment, where L. chinensisplants had grown for shorter time and there was no litter decomposition, the soil total C and N contents and the C mineralization did not differ between the endophyte-infected (E+) and endophyte-free (E-) treatments. We found no significant difference in the types of PLFAs between the E+ and the E- treatments in both field and pot experiment, but endophyte infection tended to increase the soil microbial biomass. The PLFA contents of bacteria, gram-negative bacteria (G-), fungi, and total PLFA were significantly higher in the E+ treatment than in the E- treatment in the pot experiment; whereas in the field experiment, the PLFA contents of gram-positive bacteria (G+) and actinomycetes were significantly higher in the E+ treatment than in the E- treatment. This study suggests that endophyte infection may change the soil N accumulation and the rate of C mineralization, and alter soil microbial community structure. Our findings can help with understanding the relationship between fungal endophytes and L. chinensis and its role in ecosystem C and N cycling.

Key words: C mineralization, fungal endophyte, Leymus chinensis, phospholipid fatty acid, soil microbial community

ZHOU Yong, ZHENG Lu-Yu, ZHU Min-Jie, LI Xia, REN An-Zhi, GAO Yu-Bao. Effects of fungal endophyte infection on soil properties and microbial communities in the host grass habitat[J]. Chin J Plant Ecol, 2014, 38(1): 54-61.

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URL: https://www.plant-ecology.com/EN/10.3724/SP.J.1258.2014.00006

https://www.plant-ecology.com/EN/Y2014/V38/I1/54

Figures/Tables 4

Fig. 1 Effects of fungal endophyte infection on total C (A), total N (B), and C:N (C) in pot and field soils (mean ± SE, n = 5). E+, endophyte-infected; E-, endophyte-free. Different lower-case letters indicate significant differences at p < 0.05.

Fig. 2 Soil microbial phospholipid fatty acid (PLFA) profiles with different fungal endophyte infections (mean ± SE, n = 5). A, Pot soil. B, Field soil. E+, endophyte-infected; E-, endophyte-free.

Table 1 Contents of soil microbial phospholipid fatty acids (PLFAs) in pots and field plots under different fungal endophyte infections (nmol·g-1) (mean ± SE, n = 5)

	盆栽土壤 Pot soil		样地土壤 Plot soil
	E+	E-	E+	E-
细菌 Bacteria	37.91 ± 1.12 ^a	31.85 ± 1.12 ^b	33.15 ± 2.62 ^a	27.22 ± 2.32 ^a
革兰氏阳性细菌 Gram-positive bacteria G+	1.60 ± 0.05 ^a	1.47 ± 0.11 ^a	1.60 ± 0.11 ^a	1.21 ± 0.13 ^b
革兰氏阴性细菌 Gram-negative bacteria G-	17.37 ± 1.26 ^a	12.20 ± 0.76 ^b	10.32 ± 1.12 ^a	7.89 ± 1.15 ^a
真菌 Fungi	19.19 ± 0.63 ^a	15.09 ± 0.65 ^b	13.16 ± 2.11 ^a	10.58 ± 1.38 ^a
放线菌 Actinomycetes	2.69 ± 0.08 ^a	2.39 ± 0.14 ^a	2.83 ± 0.17 ^a	1.74 ± 0.26 ^b
原生动物 Protozoa	2.59 ± 0.15 ^a	2.09 ± 0.23 ^a	1.21 ± 0.55 ^a	1.08 ± 0.18 ^a
G+:G-	0.10 ± 0.01 ^a	0.12 ± 0.01 ^a	0.16 ± 0.01 ^a	0.16 ± 0.01 ^a
真菌:细菌比值 Bacteria:fungi ratio	0.51 ± 0.02 ^a	0.48 ± 0.02 ^a	0.39 ± 0.04 ^a	0.38 ± 0.02 ^a
PLFAs总量 Total PLFAs	86.27 ± 1.14 ^a	73.06 ± 1.91 ^b	72.88 ± 7.31 ^a	56.11 ± 5.27 ^a

Fig. 3 Changes in the rate and quantity of soil C mineralization under different fungal endophyte infections (mean ± SE, n = 5). A, Soil C mineralization rate in pot soil. B, Soil C mineralization rate in field plot. C, Quantity of soil C mineralization in pot soil. D, Quantity of soil C mineralization in field plot. E+, endophyte-infected; E-, endophyte-free.

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