Belowground connections between germlings and mycorrhizal networks of arbuscular mycorrhizal fungi

摘要

Arbuscular mycorrhizal fungi (AMF), which establish mutualistic symbioses with most land plant species, are obligate biotrophs; nevertheless, their spores can germinate in the absence of the hosts. Such inconsistent behaviour, representing a strong selective disadvantage, is balanced by diverse survival strategies: a wide host range, growth arrest in the absence of host signals, unequivocal host recognition (Giovannetti et al., 1993; 1994; Logi et al. 1998; Akiyama et al., 2006). The ability of AMF hyphae to fuse (Giovannetti et al., 1999; Giovannetti et al., 2004; Croll et al., 2009) might represent a fundamental survival strategy, since germlings could plug into compatible mycorrhizal networks by means of hyphal fusions (anastomoses), thus gaining access to plant-derived carbon before undergoing any growth arrest.