Foliar Symptom Expression in Association with Early Infection and Xylem Colonization by Fusarium virguliforme (formerly F. solani f. sp. glycines), the Causal Agent of Soybean Sudden Death Syndrome

• DOI: 10.1094/php-2008-0222-01-rs
• Publication Date: 2008-06-29T18:50:02Z
• Authors: Shrishail S. Navi; X. B. Yang
• Keywords: Taproot; Fusarium solani; Radicle; Heterodera

Soybean sudden death syndrome (SDS), caused by Fusarium virguliforme (FV), is a root disease that results in severe foliar symptoms during the reproductive stage. In regular growing season, an epidemic of SDS highly correlated with planting date and tends to be more earlier planted soybeans. Occurrence infection early season likely result colonization xylem phloem tissues, process essential for symptom expression because tissues are upward pathways soybean plants. To demonstrate biology this infection, we used effective quantifiable seedling inoculation technique which germinated seeds Petri dish were spray-inoculated conidial suspension before being transplanted. Plants had showed both external internal discolored taproots basal stems, while plants no only superficial discoloration. Microtome sectioning revealed presence fungal structures tissue. A scanning electron microscope study higher penetration frequency FV near root-cap zone where few or hairs radicle found. These indicate into tissue plays role expression. Accepted publication 10 December 2007. Published 22 February 2008.