Control Strategies to Cope with Late Wilt of Maize

Control of maize late wilt disease (LWD) has been at the forefront of research efforts since the discovery of the disease in the 1960s. The disease has become a major economic restraint in highly affected areas such as Egypt and Israel, and is of constant concern in other counties. LWD causes dehydration and collapsing at a late stage of maize cultivation, starting from the male flowering phase. The disease causal agent, Magnaporthiopsis maydis, is a seed- and soil-borne phytoparasitic fungus, penetrating the roots at sprouting, colonizing the vascular system without external symptoms, and spreading upwards in the xylem, eventually blocking the water supply to the plant’s upperparts. Nowadays, the disease’s control relies mostly on identifying and developing resistant maize cultivars. Still, host resistance can be limited because M. maydis undergoes pathogenic variations, and virulent strains can eventually overcome the host immunity. This alarming status is driving researchers to continue to seek other control methods. The current review will summarize the various strategies tested over the years to minimize the disease damage. These options include agricultural (crop rotation, cover crop, no-till, flooding the land before sowing, and balanced soil fertility), physical (solar heating), allelochemical, biological, and chemical interventions. Some of these methods have shown promising success, while others have contributed to our understanding of the disease development and the environmental and host-related factors that have shaped its outcome. The most updated global knowledge about LWD control will be presented, and knowledge gaps and future aims will be discussed.

Nanoscale-specific bioassimilation of sulfur: Time and coating specific modulation of transcriptomic and metabolomic pathways in diseased tomato

Nanoscale sulfur was investigated as a multi-functional agricultural amendment to simultaneously enhance crop nutrition and suppress disease damage. Pristine (nS) and stearic acid coated (cS) sulfur nanoparticles were added to soil (0, 100, or 200 mg/L) that was planted with tomato (Solanum lycopersicum) and infested with the Fusarium wilt pathogen. Bulk sulfur (bS), ionic sulfate (iS), and healthy controls were included. In two greenhouse experiments, measured endpoints included time-dependent agronomic and photosynthetic parameters, disease severity/suppression, and a range of mechanistic biochemical and molecular endpoints, including the expression of 13 genes related to two S bioassimilation pathways and pathogenesis-response, and tissue-specific metabolomic profiles. The impact of treatment on the rhizosphere bacterial microbiome was also evaluated. Disease reduced tomato biomass by up to 87%, but amendment with nS and cS significantly reduced disease progress by 54 and 56%, respectively, compared to the infested controls. Increased S accumulation was evident in plant roots and leaves, independent of S type. Molecular analysis revealed particle size and coating-specific impacts on the plants. For nS and cS, two-photon microscopy and time-dependent gene expression data revealed a nanoscale specific elemental S bioassimilation pathway within the plant tissues. These findings correlated well with detailed metabolomic profiling of plant tissues at 4, 8, and 16 d, which exhibited increased disease resistance and plant immunity related metabolites with nanoscale treatment. The data also demonstrate a time-sensitive physiological window whereby nanoscale stimulation of plant immunity will be effective. An analysis of the rhizosphere soil bacterial community revealed minimal impacts from S soil treatments. These findings provide significant mechanistic insight into non-metal nanomaterial-based suppression of plant disease, and significantly advance efforts to develop sustainable nano-enabled agricultural strategies to increase food production.

Effects of Atmospheric CO2 and Temperature on Wheat and Corn Susceptibility to Fusarium graminearum and Deoxynivalenol Contamination

This work details the impact of atmospheric CO2 and temperature conditions on two strains of Fusarium graminearum, their disease damage, pathogen growth, mycotoxin accumulation, and production per unit fungal biomass in wheat and corn. An elevated atmospheric CO2 concentration, 1000 ppm CO2, significantly increased the accumulation of deoxynivalenol in infected plants. Furthermore, growth in cool growing conditions, 20 °C/18 °C, day and night, respectively, resulted in the highest amounts of pathogen biomass and toxin accumulation in both inoculated wheat and corn. Warm temperatures, 25 °C/23 °C, day and night, respectively, suppressed pathogen growth and toxin accumulation, with reductions as great as 99% in corn. In wheat, despite reduced pathogen biomass and toxin accumulation at warm temperatures, the fungal pathogen was more aggressive with greater disease damage and toxin production per unit biomass. Disease outcomes were also pathogen strain specific, with complex interactions between host, strain, and growth conditions. However, we found that atmospheric CO2 and temperature had essentially no significant interactions, except for greatly increased deoxynivalenol accumulation in corn at cool temperatures and elevated CO2. Plants were most susceptible to disease damage at warm and cold temperatures for wheat and corn, respectively. This work helps elucidate the complex interaction between the abiotic stresses and biotic susceptibility of wheat and corn to Fusarium graminearum infection to better understand the potential impact global climate change poses to future food security.

Ecological methods of protecting bearded irises in the urban environment

The article presents data from a long-term phytopathological survey of a collection of varieties Iris x hybrida Hort. Main Botanical Garden named after N.V. Tsitsin RAS (Moscow). Data on diseases of bearded irises in the urban environment were obtained, changes in the composition of the fungal complex in the rhizo- and phyllosphere were studied. Low soil fertility during the adaptation period of bearded irises worsens the formation and development of the root system of plants, increases the likelihood of increased disease damage and premature leaf fall. The experience of successful establishment of cultivators Iris x hybrida with the use of complex preventive and health-improving measures to improve fertility and reduce stress factors has been obtained. It was found that the introduction of NPK-complex, etching with a biofungicide based on phytobacteriomycin, and spraying vegetative plants with a microbiological preparation based on saprophytic antagonist fungi and bacteria within two years from the moment of transplanting varieties of garden bearded irises have a positive effect on their survival rate and decorative effect. The use of biological fungicides in combination with a complex of fertilizers is mandatory in a pesticide-free protection system for garden iris varieties sensitive to mycoses.

Gout Is Not Just Arthritis: Abnormal Cortical Thickness and Structural Covariance Networks in Gout

Background: Hyperuricemia is the cause of gout. The antioxidant and neuroprotective effects of uric acid seem to benefit some patients with central nervous system injury. However, changes in the brain structure have not been discovered in patients with gout.Object: Clarify the changes in cortical thickness in patients with gout and the alteration of the structural covariance networks (SCNs) based on cortical thickness.Methods: We collected structural MRIs of 23 male gout patients and 23 age-matched healthy controls. After calculating and comparing the difference in cortical thickness between the two groups, we constructed and analyzed the cortical thickness covariance networks of the two groups, and we investigated for any changes in SCNs of gout patients.Results: Gout patients have thicker cortices in the left postcentral, left supramarginal, right medial temporal, and right medial orbitofrontal regions; and thinner cortices were found in the left insula, left superior frontal, right pericalcarine, and right precentral regions. In SCN analysis, between-group differences in global network measures showed that gout patients have a higher global efficiency. In regional network measures, more nodes in gout patients have increased centrality. In network hub analysis, we found that the transfer of the core hub area, rather than the change in number, may be the characteristic of the gout's cortical thickness covariance network.Conclusion: This is the first study on changes in brain cortical thickness and SCN based on graph theory in patients with gout. The present study found that, compared with healthy controls, gout patients show regional cortical thinning or thickening, and variation in the properties of the cortical thickness covariance network also changed. These alterations may be the combined effect of disease damage and physiological compensation. More research is needed to fully understand the complex underlying mechanisms of gout brain variation.

POS0248 PSYCHOMETRIC PROPERTIES OF OUTCOME MEASUREMENT INSTRUMENTS FOR ANCA-ASSOCIATED VASCULITIS: A SYSTEMATIC LITERATURE REVIEW

Background:The OMERACT Vasculitis Working Group has defined a Core Domain Set of outcome measures for ANCA-associated vasculitis (AAV). However, the psychometric properties of available outcome measurement instruments in AAV, an essential consideration when choosing among instruments, have not been summarized.Objectives:To systematically review and summarize the psychometric properties of outcome measurement instruments used in AAV.Methods:A comprehensive search of several databases (Medline, EMBASE, Cochrane, Scopus, among others) from inception to July 14, 2020 and without language limitations was conducted. Articles were included if they covered psychometric properties of instruments used in AAV (granulomatosis with polyangiitis, GPA; microscopic polyangiitis, MPA; eosinophilic granulomatosis with polyangiitis, EGPA); articles encompassing other systemic vasculitides and not presenting the data for AAV separately were excluded. Following the COSMIN and OMERACT frameworks, different psychometric properties (validity, inter- and intra-observer reliability, sensitivity to change, and feasibility) of outcome measurement instruments used in AAV were assessed. Risk of bias was assessed according to the COSMIN checklist.Results:From 2505 articles identified, 20 met the predefined criteria. Three were identified as development studies, 14 were validation studies, and 3 pursued both objectives.These studies provided information on 16 instruments: 8 assessing disease activity, 1 assessing disease damage, 3 assessing patient-reported outcome, 4 assessing function (Figure 1). Overall, a few psychometric properties have been considered in each study, ranging from one to five. Most of the instruments were tested in GPA only (n=7), followed by AAV as a group (GPA, MPA and EGPA; n=5), MPA and GPA (n=3), and EGPA only (n=1). Sample sizes of the studies ranged between 27 and 626 patients. The studies with a higher risk of bias, according to COSMIN definitions, were those assessing RAPID3, MVIA, ENT/GPA DAS, and ODSS.There was a wide heterogeneity of the psychometric proprieties assessed for each instrument. Validity was the most frequently assessed domain in 88% of the instruments, and few properties other than construct validity were reported (Figure 1).Within each domain, BVAS/WG for activity, VDI for damage, AAV-PRO for patient-reported outcomes, and ODSS for function were the instruments with more psychometric features assessed. For the disease activity domain, BVAS/WG showed a good validity having the highest correlation with physician global assessment (r=0.90), a good reliability (intra-observer ICC=0.62; inter-observer ICC=0.97), and good feasibility and responsiveness. For disease damage, VDI showed moderate validity (correlations with BVAS/WG at 5-year with r=0.20 and BVAS/WG at 1-year with r=0.40) and good feasibility. Among patient-reported outcomes, AAV-PRO had the best performance in terms of validity (construct validity: correlations of the 6 disease domains and EQ-5D-5L, with r ranging between -0.78 and -0.55; discriminating validity between active disease versus remission of the 6 disease domains, p<0.0001 for all comparisons). The performance of instruments assessing function domain was low-to-moderate.Conclusion:Sixteen instruments covering the OMERACT domains of disease activity, damage, patient-reported outcome, and function had their psychometric properties assessed in the study of AAV. The majority were developed or validated for GPA only or AAV as a group. Overall, validity was the domain most frequently assessed. BVAS/WG, VDI, AAV-PRO, and ODSS were the instruments with more psychometric features assessed. More rigorous studies aimed at estimating a wider range of psychometric properties in larger numbers of patients with AAV are warranted.References:[1]Castrejon I, et al. Clin Exp Rheumatol. 2015[2]Merkel PA, Journal of Rheumatology, July 2011Disclosure of Interests:None declared