Element storage in spores of Gigaspora margarita Becker &amp; Hall measured by electron energy loss spectroscopy (EELS)

Andre Freire Cruz

doi:10.1590/s0102-33062004000300007

Abstract

The storage structures of spores of Gigaspora margarita Becker & Hall, an arbuscular mycorrhizal fungus, were analyzed by a transmission electronic microscope (TEM) and electron energy loss spectroscopy (EELS). The spores were hydrated, cryofixed using high pressure freezing, submitted to freeze substitution, embedded and prepared for TEM observations. The cryotechniques revealed that the storage structures in the spores are composed of lipids, electron dense granules (EDG), protein bodies and glycogen particles. The EELS detected the presence of nitrogen (N) and carbon (C) in these storage structures and in Bacteria-like organisms (BLO). Some amount of P was detected in the vacuoles and in BLO. The TEM and EELS techniques indicate the presence of storage structures in the fungal spore, and some essential elements (N, P and C) in these structures.

Highlights

Arbuscular mycorrhizal fungi (AMF) live in a symbiotic association with many land plants, and in most cases significantly change host physiology and function in support of plant growth in a variety of ways, such as the improvement of plant nutrition and increase of tolerance to environmental stress (Elliott & Coleman 1988)
The C and N stored in glomalin, a glycoprotein produced by AMF concentrated in soil (Wright & Upadhyaya 1998), can make a significant contribution to soil carbon and nitrogen pools, as the amount of these elements in AMF represents around 5% of total soil C and N (Rillig et al 2001)
This study shows the storage structures in spores of G. margarita

Summary

Introduction

Arbuscular mycorrhizal fungi (AMF) live in a symbiotic association with many land plants, and in most cases significantly change host physiology and function in support of plant growth in a variety of ways, such as the improvement of plant nutrition and increase of tolerance to environmental stress (Elliott & Coleman 1988). In addition to the intraradical structures (vesicles and arbuscules), these symbionts produces spores, which develop outside the host plant and are essential for the survival of the species and to complete the fungal life cycle. The storage pools in ectomycorrhizae are important factors for plant survival, especially during periods of low nitrogen and low photosynthetic activity (Turnau et al 2001). The C and N stored in glomalin, a glycoprotein produced by AMF concentrated in soil (Wright & Upadhyaya 1998), can make a significant contribution to soil carbon and nitrogen pools, as the amount of these elements in AMF represents around 5% of total soil C and N (Rillig et al 2001)

Methods

Results

Conclusion