Evidence for leaf endophyte regulation of root symbionts: effect of Neotyphodium endophytes on the pre-infective state of mycorrhizal fungi

• Published in: Symbiosis (Philadelphia, Pa.) Vol. 55; no. 1; pp. 19 - 28
• Main Authors: Novas, M. Victoria, Iannone, Leopoldo J., Godeas, Alicia M., Scervino, J. Martin
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Netherlands 01-08-2011; Balaban
• Subjects: Animal, plant and microbial ecology; Biological and medical sciences; Biomedical and Life Sciences; Developmental Biology; Ecology; Evolutionary Biology; Fundamental and applied biological sciences. Psychology; Life Sciences; Microbiology; Plant Sciences; Endophytes; Native grass; Interaction; Arbuscular mycorrhiza; Symbiosis; Monocotyledones; Root; Interspecific association; Plant leaf; Symbiont; Fungi; Endomycorrhiza; Gramineae; Bromus; Angiospermae; Mycorrhiza; Bromus setifolius; Neotyphodium; Endophyte; Spermatophyta; Herbaceous plant; Native species; Interspecific relation
• ISSN: 0334-5114; 1878-7665
• DOI: 10.1007/s13199-011-0140-4

Neotyphodium
endophytes and arbuscular mycorrhizal (AM) fungi are common constituents of natural grasslands. The plant–endophyte symbiosis can introduce changes in soil conditions that affect the density and activity of different functional groups of soil organisms. In the present work we performed in vitro assays to evaluate the effect of root and endophyte exudates on the pre-infective state of mycorrhizal fungi (
Gigaspora margarita
and
G. rosea
). Plant roots of
Bromus setifolius
from populations of Patagonia, and four strains of
Neotyphodium
were used to obtain the exudates. Root exudates of infected plants, at a high concentration, significantly increased AMF hyphal branches and length relative to exudates from naturally endophyte free plants. The effect of
Neotyphodium
endophyte exudates on AMF mycelial length varied depending on strain and the concentration used, suggesting a differential interaction between endophyte and AMF species. AMF hyphal branches were increased by
Neotyphodium
fungal exudates in both mycorrhizal species. A few previous studies have suggested that
Neotyphodium
endophytes can reduce mycorrhizal sporulation and colonization of host roots in commonly-cultivated agronomic hosts. In this study we report the opposite effect in
B. setifolius
. This study reports the direct and positive effect of root exudates from plants in symbiosis with
Neotyphodium
, on AMF pre-infective state. Further, identical effects were detected using exudates from
Neotyphodium
endophytes.