Phenotypic Acclimation of Maize Plants Grown under S Deprivation and Implications to Sulfur and Iron Allocation Dynamics

The aim of this work was to study maize root phenotype under sulfur deficiency stress towards revealing potential correlations between the altered phenotypic traits and the corresponding dry mass, sulfur, and iron allocation within plants at the whole-plant level. The dynamics of root morphological and anatomical traits were monitored. These traits were then correlated with plant foliage traits along with dry mass and sulfur and iron allocation dynamics in the shoot versus root. Plants grown under sulfate deprivation did not seem to invest in new root axes. Crown roots presented anatomical differences in all parameters studied; e.g., more and larger xylem vessels in order to maximize water and nutrient transport in the xylem sap. In the root system of S-deficient plants, a reduced concentration of sulfur was observed, whilst organic sulfur predominated over sulfates. A reduction in total iron concentration was monitored, and differences in its subcellular localization were observed. As expected, S-deprivation negatively affected the total sulfur concentration in the aerial plant part, as well as greatly impacted iron allocation in the foliage. Phenotypic adaptation to sulfur deprivation in maize presented alterations mainly in the root anatomy; towards competent handling of the initial sulfur and the induced iron deficiencies

Aerenchyma formulation in roots of maize during sulphate starvation

Young maize (Zea mays L., Poaceae) plants were grown in a complete, well-oxygenated nutrient solution and then deprived of their external source of sulphate. This treatment induced the formation of aerenchyma in roots. In addition to the effect of sulphate starvation on root anatomy, the presence and location of superoxide anions and hydrogen peroxide, and changes in calcium and pH were examined. By day 6 of sulphate deprivation, aerenchyma started to form in the roots of plants and the first aerenchymatous spaces were apparent in the middle of the cortex. S-starvation also induced thickening of the cell walls of the endodermis. Active oxygen species appeared in groups of intact mid-cortex cells. Formation of superoxide anion and hydrogen peroxide was found in degenerating cells of the mid-cortex. Very few nuclei in the cortex of S-starved roots fluoresced, being shrunken and near to the cell wall. By day 12 of S-deprivation, a fully developed aerenchyma was apparent and there were only a few 'chains' of cells bridging hypodermis to endodermis and stele of roots. Cell walls of endodermis of S-starved roots increased 68% in thickness. Intensive fluorescence in the cell walls of the endodermal, hypodermal and to a lesser extent of epidermal cells was observed due to the formation of active oxygen species, while there was no fluorescence in the cortical cells. There was a higher Ca concentration in the cells walls of the endodermis and epidermis, compared to the rest of the S-starved root tissues. A higher pH was observed, mainly in the cell walls of the hypodermis and to a lesser extent in the cell walls of the endodermis. Superoxide anion and hydrogen peroxide was found in degenerating cells of the root cortex. There was no fluorescence of nuclei in the cortex of S-starved roots.&nbsp

Covid-19 pandemic impact on seasonal flu vaccination: A cross-sectional study

INTRODUCTION Vaccination against the flu is the best method for the prevention of illness by influenza viruses. The objective of this study was to assess the impact of the COVID-19 pandemic on the seasonal influenza vaccination attitudes in Greece and to identify factors associated with a positive change in participants’ choice to vaccinate against the flu. METHODS This is a sub-analysis of a cross-sectional nationwide survey (n=1004) that was conducted between 28 April and 3 May 2020 using a mixed methodology for data collection: computer assisted telephone interviewing (CATI) and computer assisted web interviewing (CAWI). Sampling followed a proportionate, stratified by region, systematic procedure to ensure a nationally representative sample of the urban/rural population. Data were collected using a structured questionnaire consisting of four parts: 1) demographics; 2) knowledge about COVID-19; 3) attitudes toward COVID-19; and 4) practices to control COVID-19 and vaccination against the flu. RESULTS Of the respondents, 66.3% (n=665) had not been vaccinated for seasonal influenza during the 2019–2020 season, the period prior to the COVID-19 pandemic. However, of those, 21.8% showed willingness to receive the vaccine (n=145) the upcoming flu season 2020–2021. Factors independently associated with increased intention to vaccinate in those that had not been vaccinated the previous flu season included: age ≥65 years; the belief that vaccination against the flu is considered preventive against the spread of the coronavirus; not believing that coronavirus was man-made in a laboratory; and not believing that the pandemic will end once a large percentage of the population is infected. CONCLUSIONS Factors that shift public opinion in favor of seasonal flu vaccination can be utilized to design effective strategies to increase vaccination uptake. © 2021 Kopsidas I. et al