The pivotal role of cultivar affinity to arbuscular mycorrhizal fungi in determining mycorrhizal responsiveness to water deficit.

Arbuscular mycorrhizal fungi (AMF) have gained remarkable importance, having been proved to alleviate drought stress-induced damage in wheat due to their ability to ameliorate plant water use efficiency and antioxidant enzyme activity. However, despite the current relevance of the topic, the molecular and physiological processes at the base of this symbiosis never consider the single cultivar affinity to mycorrhization as an influencing factor for the metabolic response in the AMF-colonized plant. In the present study, the mycorrhizal affinity of two durum wheat species (T. turgidum subsp. durum (Desf.)) varieties, Iride and Ramirez, were investigated. Successively, an untargeted metabolomics approach has been used to study the fungal contribution to mitigating water deficit in both varieties. Iride and Ramirez exhibited a high and low level of mycorrhizal symbiosis, respectively; resulting in a more remarkable alteration of metabolic pathways in the most colonised variety under water deficit conditions. However, the analysis highlighted the contribution of AMF to mitigating water deficiency in both varieties, resulting in the up- and down-regulation of many amino acids, alkaloids, phenylpropanoids, lipids, and hormones.

Perspective on the status and behaviour of SARS-CoV-2 in soil.

Soil contamination by SARS-CoV-2 is highly probable because soil can collect several transporters of the virus, such as fallout aerosols, wastewaters, relatively purified sludges, and organic residues. However, the fate and status of SARS-CoV-2 in soil and the possible risks for human health through contaminated food are unknown. Therefore, this perspective paper discusses the challenges of determining the SARS-CoV-2 in soil and the mechanisms concerning its adsorption, movement, and infectivity in soil, considering what has already been reported by perspective papers published up to May 2021. These issues are discussed, drawing attention to the soil virus bibliography and considering the chemical structure of the virus. The mechanistic understanding of the status and behavior of SARS-CoV-2 in soil requires setting up an accurate determination method. In addition, future researches should provide insights into i) plant uptake and movement inside the plant, ii) virus adsorption and desorption in soil with the relative infectivity, and iii) its effects on soil functions. Models should simulate spatial localization of virus in the soil matrix.

The extracellular DNA can baffle the assessment of soil bacterial community, but the effect varies with microscale spatial distribution.

Environmental DNA is made-up of intracellular (iDNA) and extracellular (eDNA) pools. In soils, eDNA can be present up to 40% and could distort the assessment of living microorganisms. Distribution of microbial community is inconsistent among different size-aggregates, and the persistence and turnover of eDNA are thus uneven. Uneven persistence and distribution of eDNA could lead to heterogeneity in community analysis biases that arise due to eDNA sequences at micro-scale distribution. Here, we investigated the diversity and structure of eDNA and iDNA bacterial communities in bulk soil and different size-aggregates. Significant differences were observed between eDNA and iDNA bacterial diversity and composition. Changes in community composition are more important than the amount of eDNA to assess the biases caused by eDNA in community analysis. Furthermore, variations were also observed in aggregates-levels for eDNA and iDNA community which indicates that colonization pattern of iDNA community and protection of eDNA through absorbance on particle surface within soil-matrix is heterogeneous. Our work provides empirical evidence that eDNA presence could mask the detection of aggregates-level spatial dynamics in soil microbial community and have potential to qualitatively baffle observed live effects of given treatment by adequately muting the actual response dynamics of the soil microbiome.

Preliminary evidences of the presence of extracellular DNA single stranded forms in soil.

The relevance of extracellular DNA (eDNA) in the soil ecosystem is becoming more and more evident to the scientific community by the progressive discovery of functions accompanying to natural gene transformation. However, despite the increased number of published articles dedicated to eDNA in soil, so far only few are focused on its single stranded form (eDNAss). The present paper is the first to investigate the quantitative relevance of eDNAss in the total soil eDNA pool, discriminating between its linear (eDNAssl) and circular (eDNAssc) forms and the respective weakly (wa) and tightly (ta) adsorbed fractions. The results showed the prevalence of eDNAss and its linear form in both the total soil eDNA pool and its wa and ta fractions. Both of the eDNAss fractions (linear and circular) were characterized by small fragments.