Temporal Dynamics of Fusarium virguliforme Colonization of Soybean Roots

Abstract

Soybean sudden death syndrome (SDS) caused by Fusarium virguliforme is one of the most yield limiting soybean diseases in the United States. SDS disease symptoms include root rot and foliar symptoms induced by fungal toxins. Soybean cultivar resistance is one of the most effective SDS disease management options, but no cultivar displays complete resistance. Soybean SDS foliar symptoms are the primary phenotype used to screen and breed for SDS resistance. Root rot or root colonization measures are seldom utilized, partly due to the lack of convenient and accurate methods for quantification of F. virguliforme. In this study, greenhouse and field experiments were conducted to determine the temporal dynamics of F. virguliforme colonization of soybean roots using quantitative real-time PCR (qPCR). The infection coefficient (IC), or ratio of F. virguliforme DNA to soybean DNA, was determined in soybean cultivars with different SDS foliar resistance ratings. In greenhouse experiments, F. virguliforme was detected in all cultivars 7 days after planting (DAP), with a peak in IC at 14 DAP. All soybean cultivars developed SDS foliar symptoms, but F. virguliforme soybean root colonization levels did not significantly correlate with SDS foliar symptom severity. In field experiments, SDS foliar symptoms developed among soybean cultivars in alignment with provided foliar resistance ratings; however, the F. virguliforme IC were not significantly different between SDS foliar symptomatic and asymptomatic cultivars. F. virguliforme was detected in all cultivars at the first sample collection point 25 DAP (V3 vegetative growth stage), and the IC increased throughout the season, peaking at the last sample collection point 153 DAP (postharvest). Collectively, appearance and disease severity ratings of SDS foliar symptoms were not associated with F. virguliforme quantity in roots, suggesting a need to include F. virguliforme root colonization in breeding efforts to screen soybean germplasm for F. virguliforme root infection resistance. The findings also demonstrates root colonization of the pathogen on nonsymptomatic soybean cultivars leading to persistence of the pathogen in the field, and possible hidden yield loss.

Fluopyram Sensitivity and Functional Characterization of SdhB in the Fusarium solani Species Complex Causing Soybean Sudden Death Syndrome

“…Pro-Ized red seed colorant (Gustafson LLC) and finisher (Peridiam Precise 1010; Bayer CropScience) were added at the rate of 32.6 and 65 ml/100kg of seed, respectively. Fungal inoculum was prepared by the method used in Wang et al (2018) . Briefly, each strain was grown on Nash-Snyder (NS) medium for 14 days at room temperature.…”

Soybean sudden death syndrome: Fungal pathogenesis and plant response

“…Microsatellites are tandem repeat copies of simple sequence repeats (1-6 bp in length) that are highly mutagenic. Microsatellite markers have been applied to F. virguliforme strains to determine the genetic diversity of fungal isolates within one geographical location and to assess marker transferability to closely related Fusarium species (Wang and Chilvers, 2019b). Twelve reproducible and highly polymorphic microsatellite markers were sufficient to detect F.…”

“…Twelve reproducible and highly polymorphic microsatellite markers were sufficient to detect F . virguliforme genetic diversity and all but one marker also amplified all the closely related soybean SDS pathogens (Wang and Chilvers, 2019b). Thus, this technique proved to be valuable for elucidation of genetic diversity of Fusarium species in clade 2 of the FSSC.…”

Effects of Root Rot in Soybean Cultivars with Diverse Susceptibility to the Disease on Plant Physiology, Yield, Amino Acids and Mycotoxins Profile in Climatic Conditions of Kazakhstan

“…Common fungal diseases are sudden death syndrome, damping-off and root rot, which are caused by Fusarium oxysporum (Cruz Jimenez et al, 2018;Chang et al, 2018;McLaren and Callahan. 2020), F. equiseti (Kuldybayev et al, 2019;You and Barbetti, 2017), F. virguliforme (Wang et al, 2019) under certain environmental conditions. Soil-borne diseases contribute to the decrease of roots length and weight, length of plant, weaken general plant condition and in consequence contribute to lower yield (Dutbayev et al, 2020c).…”