Altered allocation to roots and shoots in the endophyte‐infected seedlings of Puccinellia distans (Poaceae)

Abstract

Endophytes play an important role in ecological and evolutionary processes in plants and have marked economic value. Seed-transmitted fungal endophytes are conventionally regarded as mutualistic symbionts, but their fitness consequences for the offspring of the host are not clear. Puccinellia distans infected with the fungus Epichloë typhina (E+) produces seeds that are several times smaller than normal (E-). This observation suggests that the E+ seedlings face a developmental disadvantage. Our growth chamber experiments compared the germination rates of the small E+ and large E- seeds of P. distans and examined the biomass allocation of seedlings to roots and shoots. The E+ seedlings germinated more slowly and maintained shorter shoots and a smaller root biomass for 30-50 days after sowing. Despite this disadvantage, the E+ plants more quickly increased their total size, attaining a larger shoot and whole-plant biomass. The shoot:root biomass ratio increased more rapidly through time in the E+ seedlings, attaining a value nine times higher in the E+ than the E- group 50 days after sowing. Such differences between the E+ and E- seedlings were not explained by the growth allometry between shoots and roots. The seedlings of P. distans infected with the Epichloë endophyte were initially handicapped by their postponed emergence, but this disadvantage was quickly overcome by their superior growth capacity. The decrease in the relative allocation to roots may indicate that endophytes increase the performance of roots as resource-acquiring organs and/or reduce the role of roots in protection against herbivores.

Incidence, Identification, and Mycoparasitic Activity of Clonostachys epichloë, a Hyperparasite of the Fungal Endophyte Epichloë typhina

“…E. typhina has been recorded in five populations of P. distans, with all growing in anthropogenic habitats (Lembicz and Olejniczak 2009). The association between E. typhina and P. distans has already been investigated in several studies (Czarnoleski et al 2013;Górzyńska et al 2011Górzyńska et al , 2017Lembicz et al 2011Lembicz et al , 2013Olejniczak and Lembicz 2007); we reported a previously unrecorded hyperparasite appearing as dark green spots on E. typhina stromata in 2010 (M. Lembicz and K. Górzyńska, annual report, unpublished).…”

Endophyte traits relevant to stress tolerance, resource use and habitat of origin predict effects on host plants

“…Fungal endophytes that are horizontally transmitted and non-Clavicipitaceous (hereafter 'endophytes') reside within the tissues of nearly all terrestrial plants and can mediate plant stress tolerance via effects on plant physiology and gene expression (Arnold & Engelbrecht, 2007;Rodriguez et al, 2009;Czarnoleski et al, 2012;Torres et al, 2012). However, endophytic fungi can range from antagonistic to mutually beneficial (Carroll, 1988), making the development of a predictive framework for symbiont outcomes key to both a basic understanding and potential applications of endophytic fungi.…”

Effect of the anther‐smut fungus Microbotryum on the juvenile growth of its host Silene latifolia

“…Indeed, many of the classical well‐documented endophytes in the Clavicipitaceae also wholly or partially sterilize their hosts by producing their fruiting body (stroma) on the inflorescence (Bradshaw, ; Clay and Leuchtmann, ; Schardl et al., ). Many of these endophytes are seed‐transmitted, and experiments with “cured” and uncured seeds have shown effects on seedling growth and survival (Faeth and Hamilton, ; Gibert and Hazard, ), as well as on root/shoot ratios (Czarnoleski et al., ). Correspondingly, it is increasingly recognized that many endophytes are simply the nonfruiting hyphal stage of fungi that under other conditions or at other life stages may have overt pathogenic effects (Slippers and Wingfield, ; Newton et al., ; Junker et al., ).…”