86
A. Chanda et al.
3 Plants and Mycorrhizal Fungi: Effect of Climate Change
on This Relationship
Abiotic stress is common in all agricultural environments as drought, temperature,
salinity and nutrient deficiency or excess all have negative consequence on plant
strength. However several lines of evidence suggest that plant-mycorrhizal fungi
offer several beneficial effects to the host and increase their resistance to this stress.
Approximately 6000 species of Glomeromycota, Ascomycota, and Basidiomycota
have been stated as mycorrhizal fungi. Discussed here are a collection of such studies
that demonstrate the importance of mycorrhizal fungi in protecting plants from the
abiotic stressors and thereby are linked with increased agricultural productivity.
Arbuscular mycorrhizal fungi (AMF) symbiosis are obligate symbionts that colonize land plant root. These fungi receive carbohydrates from plant host and improve
plant nutrient and water availability [4]. Elevated carbon dioxide levels usually
enhance the colonization of these mycorrihizal fungi, which in turn promotes plant
growth. However, in many ecosystems, plant growth promotion is limited by nutrient
availability. Therefore elevation of carbon dioxide levels will not necessarily increase
agricultural productivity under these field conditions [5]. The rise in temperature has
a positive effect on arbuscular fungi colonization and hyphal length. It may also alter
the structure of the AMF hyphal network and initiate a switch from vesicular hyphae
responsible for storage in the cooler soil to extra mycorrihizal hyphal representing
growth in warmer soils. This may be responsible for faster carbon distribution to the
rhizosphere and improved respiration of the extra mycorrihizal hyphae at a high soil
temperature. AMF may enhance plant growth and colonization for the majority of
strains Glomus intraradices and Glomus mossae at a higher temperature. Drought
stress can be a result of global warming. Studies show that drought improves arbuscule formation and hyphae enlargement of Glomus spp. (e.g. strain ZAC-19), but
reduces its colonization (e.g. Glomus fasciculatum). Drought is responsible for the
reduction of plant growth and both roots and aerial plant parts may be compressed.
This may lead to changes in the distribution of photosynthates in the rhizosphere as
well as in extra mycorrhizal mycelium.
Various plant species, most importantly forest trees, interact with ectomycorrhizal
(ECM) fungi which in concert with AMF provide organic nitrogen, phosphate and
other micronutrients to their plant hosts and also enhance seedling survival. Similar to AMF, elevated CO 2 concentrations may induce changes in ECM colonization
and/or community structures. It has been reported that mycelial biomass production by Hebeloma crustuliniforme in Pinus sylvestris (L.) Karst. Seedlings increased
three-fold under elevated CO 2 , as compared to mycelial growth under ambient CO 2
conditions [6]. The mycorrhizal fungus Pisolithus tinctorius, which depended on
plant assimilates of Pinus silvestris L., grew much faster in the presence of elevated
CO 2 , three fold higher mycorrhizal root clusters and two-fold higher biomass of
extra mycorrhizal mycelia as compared to ambient CO 2 levels. These studies demonstrate that increased CO 2 can increase ECM colonization of host plants, although as
A. Chanda et al.
3 Plants and Mycorrhizal Fungi: Effect of Climate Change
on This Relationship
Abiotic stress is common in all agricultural environments as drought, temperature,
salinity and nutrient deficiency or excess all have negative consequence on plant
strength. However several lines of evidence suggest that plant-mycorrhizal fungi
offer several beneficial effects to the host and increase their resistance to this stress.
Approximately 6000 species of Glomeromycota, Ascomycota, and Basidiomycota
have been stated as mycorrhizal fungi. Discussed here are a collection of such studies
that demonstrate the importance of mycorrhizal fungi in protecting plants from the
abiotic stressors and thereby are linked with increased agricultural productivity.
Arbuscular mycorrhizal fungi (AMF) symbiosis are obligate symbionts that colonize land plant root. These fungi receive carbohydrates from plant host and improve
plant nutrient and water availability [4]. Elevated carbon dioxide levels usually
enhance the colonization of these mycorrihizal fungi, which in turn promotes plant
growth. However, in many ecosystems, plant growth promotion is limited by nutrient
availability. Therefore elevation of carbon dioxide levels will not necessarily increase
agricultural productivity under these field conditions [5]. The rise in temperature has
a positive effect on arbuscular fungi colonization and hyphal length. It may also alter
the structure of the AMF hyphal network and initiate a switch from vesicular hyphae
responsible for storage in the cooler soil to extra mycorrihizal hyphal representing
growth in warmer soils. This may be responsible for faster carbon distribution to the
rhizosphere and improved respiration of the extra mycorrihizal hyphae at a high soil
temperature. AMF may enhance plant growth and colonization for the majority of
strains Glomus intraradices and Glomus mossae at a higher temperature. Drought
stress can be a result of global warming. Studies show that drought improves arbuscule formation and hyphae enlargement of Glomus spp. (e.g. strain ZAC-19), but
reduces its colonization (e.g. Glomus fasciculatum). Drought is responsible for the
reduction of plant growth and both roots and aerial plant parts may be compressed.
This may lead to changes in the distribution of photosynthates in the rhizosphere as
well as in extra mycorrhizal mycelium.
Various plant species, most importantly forest trees, interact with ectomycorrhizal
(ECM) fungi which in concert with AMF provide organic nitrogen, phosphate and
other micronutrients to their plant hosts and also enhance seedling survival. Similar to AMF, elevated CO 2 concentrations may induce changes in ECM colonization
and/or community structures. It has been reported that mycelial biomass production by Hebeloma crustuliniforme in Pinus sylvestris (L.) Karst. Seedlings increased
three-fold under elevated CO 2 , as compared to mycelial growth under ambient CO 2
conditions [6]. The mycorrhizal fungus Pisolithus tinctorius, which depended on
plant assimilates of Pinus silvestris L., grew much faster in the presence of elevated
CO 2 , three fold higher mycorrhizal root clusters and two-fold higher biomass of
extra mycorrhizal mycelia as compared to ambient CO 2 levels. These studies demonstrate that increased CO 2 can increase ECM colonization of host plants, although as