ARS | Publication request: Medicago truncatula mutants with an increase in mesophyll calcium oxalate accumulation

Submitted to: Meeting Proceedings
Publication Type: Proceedings
Publication Acceptance Date: May 1, 2006
Publication Date: June 1, 2006
Citation: Nakata, P.A., McConn, M. 2006. Medicago truncatula mutants with an increase in mesophyll calcium oxalate accumulation. International Symposium in Memory of Vincent R. Franceschi. Plant Cell: Structure-Function Relations. p. 63.

Technical Abstract: Plants invest a considerable amount of resources and energy into the formation of calcium oxalate crystals. A number of roles for crystal formation in plant growth and development have been assigned based on the prevalence of crystals, their spatial distribution, and the variety of crystal shapes. Although calcium oxalate formation in plants is common, our understanding of calcium oxalate crystal formation and distribution are still incomplete. In this study we report the identification and characterization of M. truncatula mutants with increased calcium oxalate content. In each mutant the increase in calcium oxalate content resulted from an increase in druse crystal deposition in the mesophyll cells of leaves. These plants were referred to as mesophyll oxalate defective (mod) mutants. The mod mutants were isolated by visually screening leaves from an ethyl methanesulfonate (EMS) mutagenized M. truncatula population using a light microscope and partially polarized light for increased druse crystal abundance in the mesophyll cells. Another similar mutant characterized in this study, cod 4, was isolated in a previous screen. Genetic analysis revealed that each mutation was recessive and resided in different loci. Thus, a number of mutations can result in increased druse crystal formation in mesophyll cells. Ascorbic acid, chlorophyll, and starch measurements showed an inverse correlation with oxalate content. Such findings suggest that increases in oxalate deposition may be linked to a number of other processes and pathways. It is our hope that the information gained through the analysis of these mutants will be applicable toward future efforts to improve the production and nutritional content of plant foods.