Preparing and staining mycorrhizal structures in dry bean, sweet corn, and wheat using a block digester

Abstract

The use of safe staining techniques in the evaluation of mycorrhizal colonization is critical to the continued understanding of this important symbiosis. Several procedures being utilized currently involve regulated and/ or toxic chemicals. The integration of unregulated and nontoxic chemicals into these procedures is important to alleviate potential dangers currently used chemicals pose. We eliminated all regulated reagents by combining portions of several previously published staining and root preservation procedures. A block digester for plant tissue digestion was used as a heating unit and proved to be easier to use, quicker and more reliable than either a water bath or a circulating air oven. Optimum clearing time in KOH varied from 8 to 10 min and 30 to 40 min for wheat, sweet corn, and dry bean roots, respectively. We also successfully used both drying and freezing of roots for storage prior to staining. These modified procedures were quick and easy and provided reliable temperature control and excellent staining while protecting individuals and the environment from toxic chemicals.