Glomalin: A Potential Soil Conditioner for Perennial Fruits

Glomalin, a special glycoprotein secreted by hyphae and spore walls of arbuscular mycorrhizal fungi (AMF), possesses some diverse characteristics, of them its hydrophobic nature and stability to heat are most profound. Glomalin sloughs off cementing material following the hyphal degradation that coat soil organic matter and soil particles, thereby, forming a protective surface layer against loss of water and nutrients from soil aggregates. These properties of glomalin would influence plant and/or soil water relations. Assessed through Braford assay, glomalin contains proteins of non-AMF and AMF origin, in addition to large amount of soil-related heat-stable proteins, collectively defined as glomalin-related soil protein (GRSP) in soils. In perennial fruits, GRSP concentration has been observed up to 1 mg/g DW soil, which is strongly affected by physiography, soil management practices, and season. GRSP represents a type of glue agent that stabilizes soil aggregates, as one of the fractions of soil organic matter in perennial fruit orchards. There is an increasing demand to discern whether the functionings of exogenous GRSP application is similar to those of endogenously synthesized GRSP. These accrued results provide strong support in favour of glomalin as a potential soil conditioner that holds promise in perennial fruits. This review also makes a