Auxin (indole-3-acetic acid, IAA) has been implicated as a susceptibility factor in both beneficial and pathogenic molecular plant−microbe interactions. Previous studies have identified a large number of auxin-related genes underlying quantitative disease resistance loci (QDRLs) for Phytophthora sojae. Thus, we hypothesized that auxin may be involved the P. sojae−soybean interaction. The levels of IAA and related metabolites were measured in mycelia and media supernatant as well as in mock and inoculated soybean roots in a time course assay. The expression of 11 soybean Pin-formed (GmPIN) auxin efflux transporter genes was also examined. Tryptophan, an auxin precursor, was detected in the P. sojae mycelia and media supernatant. During colonization of roots, levels of IAA and related metabolites were significantly higher in both moderately resistant Conrad and moderately susceptible Sloan inoculated roots compared with mock controls at 48 h postinoculation (hpi) in one experiment and at 72 hpi in a second, with Sloan accumulating higher levels of the auxin catabolite IAA-Ala than Conrad. Additionally, one GmPIN at 24 hpi, one at 48 hpi, and three at 72 hpi had higher expression in inoculated compared with the mock control roots in Conrad. The ability of resistant cultivars to cope with auxin accumulation may play an important role in quantitative disease resistance. Levels of jasmonic acid (JA), another plant hormone associated with defense responses, were also higher in inoculated roots at these same time points, suggesting that JA also plays a role during the later stages of infection.

Fusarium head blight (FHB) and the associated mycotoxin deoxynivalenol (DON) negatively impact the wheat industry worldwide. In North America, FHB is mainly caused by Fusarium graminearum sensu stricto. The purpose of this study was to evaluate, under storage conditions, the expression of the DON biosynthetic gene trichodiene synthase (Tri5) of F. graminearum in grain of hard red winter wheat cultivars ‘Overley’ (FHB-susceptible) and ‘Overland’ (moderately resistant to FHB) from field plots treated or untreated with the triazole fungicide Prosaro and the strobilurin fungicide Headline. Infected grain was stored and periodically sampled to determine gene expression by qRT-PCR analysis. The F. graminearum housekeeping gene GAPDH was consistently detected, indicative of metabolically active fungi, and Tri5 detection was significantly higher in ‘Overley’ compared with ‘Overland’. Tri5 gene expression and DON concentrations showed little to no correlation; consequently, Tri5 expression levels did not accurately predict DON concentrations. The strobilurin did not significantly reduce Tri5 gene expression compared with untreated wheat. In the triazole treatment, a significant reduction in the relative expression of Tri5 was detected after 120 days, as well as a downregulation of Tri5 from 60 to 120 days of storage in ‘Overley’. In grain from strobilurin-treated plots of both cultivars, the expression of Tri5 increased from 0 to 30 days after tempering. Genetic expression of Tri5 that is necessary for the production of DON can increase during storage of high-moisture grain. Fusarium fungi can persist in wheat kernels for several months postharvest and may actively produce toxin during this period.

Introduction: In Ecuador, the first COVID-19 case, the disease caused by the SARS-CoV-2 virus, was officially reported on February 29, 2020. As of April 2, the officially confirmed numbers of COVID-19 cases and deaths from it were 3 163 and 120, respectively, that is, a mortality rate of 3.8%. Objective: To identify spatial and spatiotemporal clusters of COVID-19 cases officially confirmed in Ecuador. Materials and methods: Case series study. An analysis of all COVID-19 cases officially confirmed in Ecuador from March 13, 2020 to April 2, 2020 was performed. Relative Risk (RR) of COVID-19 contagion was determined using the discrete Poisson distribution model in the SaTScan software. Clusters were generated using purely spatial and spatiotemporal scan statistics. Significance of each cluster was obtained through 999 iterations using the Monte Carlo simulation, obtaining the most probable random model. Results: As of April 2, spatiotemporal clustering allowed identifying two clusters in Ecuador, a main cluster in the Guayas province (area: 15 430 km2; population: 3.6 million inhabitants; RR: 7.08; p<0.000001; calculated annual incidence 1700 cases / 100 000 people) and a secondary cluster in the Pichincha province (area: 88 904 km2; population: 7.1 million; RR: 0.38; p<0.000001; calculated annual incidence 737 cases / 100 000 people.) Conclusions: The implementation of COVID-19 mitigation strategies should be focused on areas of high transmission risk; therefore, spatial, and spatiotemporal clustering with SaTScan can be extremely useful for the early detection and surveillance of COVID-19 outbreaks.

In NorthAmerica, Fusarium graminearum is the main causal agent of Fusarium head blight (FHB), an important wheat disease in the region. In 2015, severe and widespread FHB epidemics occurred in wheat in Nebraska, USA. Symptomatic wheat spike samples (20 to 30 spikes/sample) at the hard dough growth stage were collected from 23 fields (1 sample/field) in 15 counties representing all the major wheat growing regions in the state (southeast, south central, southwest, and northwest). DNA was extracted from single-spored isolates grown on PDA using the DNeasy Plant Mini Kit (Qiagen, Hilden, Germany). A portion of the translation elongation factor 1-α (EF-1α) gene from a subset of the isolates was amplified using primers EF-1f (CGACCACTGTGAGTACCA) and EF-1r (GTCAAGAACCCAGGCGTA) (Ward et al. 2008) and bidirectionally sequenced. The sequences, deposited in GenBank under accession numbers MH379136 to MH379138 and MH392474 to MH392477, were analyzed and assembled in MEGA7, and BLAST queries were performed in Fusarium...

Numerous sources of putative novel resistance genes toward Phytophthora sojae ( Rps genes) have been identified and loci mapped in soybean ( Glycine max L. Merr.) but cloning has remained elusive. We utilized resistance gene enrichment sequencing (RenSeq) to identify the putative resistance genes in 20 plant introductions (PIs) and differentials of the cultivar Williams with rps , Rps1c , Rps3a , and Rps8 . The DNA from these genotypes was enriched and sequenced using more than 25,000 80 nt baits designed to nucleotide‐binding leucine‐rich repeat (NLR) encoding sequences. Overall, there were greater numbers of variants in the NLR‐encoding genes in Rps loci on chromosomes (Chrs) 3, 7, 13, and 18 for the 20 PIs as compared to the Williams differentials for rps , Rps1c , Rps1k , Rps3a , and Rps8 . Genes encoding Rps1c , Rps3a , and Rps8 were proposed based on sequence differences among the differentials. Among the 20 PIs, there may be additional alleles on Chrs 3, 13, and 18, and PI399079 may have two new alleles at Chrs 3 and 7 loci. A unique NLR on Chr 8 was identified in PI200553. New alleles were also identified on Chrs 3 and 18 when the PI and resistant bulks were compared to susceptible recombinant inbred lines. This study demonstrates the utility of RenSeq as an efficient method to identify and predict specific novel NLR genes in landrace soybean germplasm, which confer resistance to P. sojae and obtain gene‐specific markers to facilitate their introgression into modern cultivars.