Aggressiveness of Fusarium Species and Impact of Root Infection on Growth and Yield of Soybean.

Iowa State University, Plant Pathology and Microbiology, Ames, Iowa, United States
Phytopathology (Impact Factor: 3.12). 03/2013; 103(8). DOI: 10.1094/PHYTO-08-12-0207-R
Source: PubMed


Fusarium spp. are commonly isolated from soybean roots but the pathogenic activity of most species is poorly documented. Aggressiveness and yield impact of nine species of Fusarium were determined on soybean in greenhouse (50 isolates) and field microplot (19 isolates) experiments. Root rot severity and shoot and root dry weights were compared at growth stages V3 or R1. Root systems were scanned and digital image analysis was conducted; yield was measured in microplots. Disease severity and root morphology impacts varied among and within species. F. graminearum was highly aggressive (root rot severity >90%), followed by F. proliferatum and F. virguliforme. Significant variation in damping-off (20 to 75%) and root rot severity (<20 to >60%) was observed among F. oxysporum isolates. In artificially-infested microplots, root rot severity was low (<25%) and mean yield was not significantly reduced. However, there were significant linear relationships between yield and root symptoms for some isolates. Root morphological characteristics were more consistent indicators of yield loss than root rot severity. This study provides the first characterization of aggressiveness and yield impact of Fusarium root rot species on soybean at different plant stages and introduces root image analysis to assess the impact of root pathogens on soybean.

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Available from: Maria Mercedes Diaz Arias, Feb 06, 2015
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    • "These arguments were based on failed attempts to complete Koch's postulates, following direct inoculations of seedling hypocotyls or applications of spore suspensions of F. graminearum to flowers (Fernandez and Fernandes 1990). At present F. graminearum is recognized as a primary pathogen of soybean in several countries in the American continents (Broders et al. 2007; Diaz Arias et al. 2013; Ellis et al. 2011; Martinelli et al. 2004; Pioli et al. 2004; Xue et al. 2007). Soybean (Glycine max L. Merr.) is the most important field crop in Argentina, where the planted area has reached 11,000,000 ha with annual production approximately 35,000,000 metric tonnes (MAGPyA (http:// "
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    ABSTRACT: Soybean (Glycine max L.) is one of the main crops in Argentina. Most of the studies of pathogenicity in the Fusarium graminearum complex have focused on strains isolated from wheat and maize, and there is little information on strains isolated from soybean. Our objective in the present study was to compare the pathogenicity among soybean isolates of different phylogenetic species within the Fusarium graminearum complex on soybean seedlings under controlled conditions. Six strains representing three different phylogenetic species (F. graminearum, F. meridionale and F. cortaderiae) were identified by partial sequencing of the Translation Elongation Factor -1α gene (TEF-1) and evaluated for pathogenicity. All six strains reduced emergence, mainly by causing pre-emergence damping-off, seedling height and root dry weight and produced abnormal seedlings. The mean disease severity averaged across all isolates was approximately 3.0 in a 0–4 rating scale where 0 = healthy seedling and 4 = dead seedling. Significant differences in pathogenicity were observed among F. graminearum, F. meridionale and F. cortaderiae. These results are consistent with the hypothesis that different phylogenetic species within the Fusarium graminearum complex isolated from soybean are pathogenic under controlled conditions to soybean seedlings in Argentina. The present study demonstrates for the first time the pathogenic effect of F. meridionale on soybean in Argentina.
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