Biology and epidemiology of seedborne pathogens: Features that favor seed transmission and the implications for risk analysis

• Published in: Phytopathology Vol. 96; no. 6; p. S161
• Main Authors: Randall-Schadel, B L, Walcott, R
• Format: Journal Article
• Language: English
• Published: 01.06.2006
• Subjects: Acidovorax; Cylindrocladium parasiticum; Phomopsis
• ISSN: 0031-949X

This overview focuses on the aspects of seed biology that are important for the transmission and survival of microorganisms, including pathogens, parasites or mutualistic symbionts, and the movement of pathogens with seed in international trade of agricultural commodities. To be seed transmitted, microorganisms must be able to access the seed, either through active (i.e. systemic movement or crossing the ovary wall) or passive (i.e., contaminating the surface of the seed or the seed lot) mechanisms. They must also be able to survive commercial production practices, and establish infection on emerging seedlings. Pathogens discussed as case studies include Acidovorax avenue subsp. citrulli, Cylindrocladium parasiticum and Phomopsis longicola. Two important criteria for the movement of pathogens in the seed are 1) the presence of the pathogen at the point of origin, either associated directly with the seed or contaminating the seed lot (e.g., sclerotia, cysts); and 2) the survival of the pathogen during the movement (i.e., shipping temperatures, shipping duration, etc.). Ultimately, the ability of a seedborne pathogen to establish in a new environment, which is influenced by its seed transmission potential, must be assessed.