Mycorrhizal symbiosis has contrasting effects on fitness components in Campanula rotundifolia

Abstract

Summary• The benefits or costs of mycorrhizal symbiosis for the host plants are most frequently estimated in terms of positive or negative effects on plant growth and biomass. The effect of mycorrhizal symbiosis on evolutionarily important fitness traits, such as reproduction, and effects on the next generation are poorly known.• In a set of glasshouse experiments involving two plant generations we investigated the impact of mycorrhiza on fitness traits in perennial hand-pollinated Campanula rotundifolia .• Mycorrhiza reduced plant growth and flower production, but increased rootshoot ratio, and shoot phosphorus (P) concentration. Mycorrhiza had no effect on seed number per capsule, mean seed weight or germination rate, but increased seed P concentration. Seedlings from mycorrhizal plants had a higher relative growth rate (RGR) than seedlings from nonmycorrhizal plants. Self-pollinations yielded fewer seeds per capsule that had inferior germination than seeds from cross-pollinations.• Mycorrhizal infection was associated with a cost for the reproductive output of the C. rotundifolia host plant, whose progeny, however, were better than those from the nonmycorrhizal plants. Mycorrhiza also showed the potential to affect the plant mating system by increasing self-incompatibility and inbreeding depression expressed during seedling growth.

Mycorrhizal benefit in two low arctic herbs increases with increasing temperature

“…Although higher mycorrhiza-mediated P acquisition was not associated with improved RGR, it may still be an important component of plant fitness, because higher mycorrhiza-mediated plant [P] may improve the offspring quality (Nuortila et al, 2004). Furthermore, warming has been shown to increase seed number in alpine Ranunculus acris (Tøtland, 1999).…”

Effects of arbuscular mycorrhizas on reproductive traits in sexually dimorphic plants: a review

“…Most importantly, it seems that the sexes in dimorphic plants may gain sex-specific benefits from AM symbiosis. AM symbiosis may also affect inbreeding depression (Nuortila et al, 2004;Botham et al, 2009), which may have important consequences for plant breeding systems evolution. However, the mechanisms involved, the incidence, and the importance of sex-specific relationships between AM fungi and plants are still unknown.…”

Mycorrhizal Symbiosis and Plant Reproduction

“…In Abutilon theophrasti, an increase in seed N content improved competitive ability of the offspring (Parrish and Bazzaz 1985). An increase in seed P content can also positively affect the germination, growth or reproductive output of the offspring such as in Campanula (Nuortila et al 2004), Pisum (Austin 1966), in other legumes (Bolland and Paynter 1990), and in Hordeum (Zhang et al 1990). Thus, even when additional P supplied by the mycorrhizal fungus does not result in increased seed number (when seed production is no longer P-limited), significant consequences to the next generation of plants may still result from mycorrhizal infection of the former generation.…”

“…Most of the increase in P content of seeds of mycorrhizal plants was due to an increase in phytate-P. Other host species exhibit increased seed P concentrations as a consequence of mycorrhizal infection, including Triticum aestivum (Karagiannidis and HadjisavvaZinoviadi 1998). Such increases in seed P concentration may even occur in the absence of any positive effects on plant growth, flower production, the number of seeds per fruit or seed weight (Nuortila et al 2004).…”