Global tropospheric ozone responses to reduced NO x emissions linked to the COVID-19 worldwide lockdowns.

Efforts to stem the transmission of coronavirus disease 2019 (COVID-19) led to rapid, global ancillary reductions in air pollutant emissions. Here, we quantify the impact on tropospheric ozone using a multiconstituent chemical data assimilation system. Anthropogenic NO x emissions dropped by at least 15% globally and 18 to 25% regionally in April and May 2020, which decreased free tropospheric ozone by up to 5 parts per billion, consistent with independent satellite observations. The global total tropospheric ozone burden declined by 6TgO3 (∼2%) in May and June 2020, largely due to emission reductions in Asia and the Americas that were amplified by regionally high ozone production efficiencies (up to 4 TgO3/TgN). Our results show that COVID-19 mitigation left a global atmospheric imprint that altered atmospheric oxidative capacity and climate radiative forcing, providing a test of the efficacy of NO x emissions controls for co-benefiting air quality and climate.

Genetic transformation with untranslatable coat protein gene of sugarcane yellow leaf virus reduces virus titers in sugarcane.

Sugarcane yellow leaf syndrome, characterized by a yellowing of the leaf midrib followed by leaf necrosis and growth suppression, is caused by sugarcane yellow leaf virus (SCYLV). We produced SCYLV-resistant transgenic sugarcane from a susceptible cultivar (H62-4671) and determined the amount of virus present following inoculation. The transgenic plants were produced through biolistic bombardment of cell cultures with an untranslatable coat protein gene. Presence of the transgene in regenerated plants was confirmed using PCR and Southern blot analysis. The transgenic lines were inoculated by viruliferous aphids and the level of SCYLV in the plants was determined. Six out of nine transgenic lines had at least 10(3)-fold lower virus titer than the non-transformed, susceptible parent line. This resistance level, as measured by virus titer and symptom development, was similar to that of a resistant cultivar (H78-4153). The selected SCYLV-resistant transgenic sugarcane lines will be available for integration of the resistance gene into other commercial cultivars and for quantification of viral effects on yield.