Awaking the dormant virome in the rhizosphere.

The rhizosphere is a vital soil compartment providing key plant-beneficial functions. However, little is known about the mechanisms driving viral diversity in the rhizosphere. Viruses can establish lytic or lysogenic interactions with their bacterial hosts. In the latter, they assume a dormant state integrated in the host genome and can be awakened by different perturbations that impact host cell physiology, triggering a viral bloom, which is potentially a fundamental mechanism driving soil viral diversity, as 22%-68% of soil bacteria are predicted to harbour dormant viruses. Here we assessed the viral bloom response in rhizospheric viromes by exposing them to three contrasting soil perturbation agents: earthworms, herbicide and antibiotic pollutant. The viromes were next screened for rhizosphere-relevant genes and also used as inoculant on microcosms incubations to test their impacts on pristine microbiomes. Our results show that while post-perturbation viromes diverged from control conditions, viral communities exposed to both herbicide and antibiotic pollutant were more similar to each other than those influenced by earthworms. The latter also favoured an increase in viral populations harbouring genes involved in plant-beneficial functions. Post-perturbation viromes inoculated on soil microcosms changed the diversity of pristine microbiomes, suggesting that viromes are important components of the soil ecological memory driving eco-evolutionary processes that determine future microbiome trajectories according to past events. Our findings demonstrate that viromes are active players in the rhizosphere and need to be considered in efforts to understand and control the microbial processes towards sustainable crop production.

Changes in diapause related gene expression pattern during early embryonic development in HCl-treated eggs of bivoltine silkworm Bombyx mori (Lepidoptera: Bombycidae)

Investigation of differential expression of diapause related genes (five metabolic, five heat shock protein and one translational regulatory) in HCl-treated (non-diapause) and untreated (diapause) eggs of B. mori during early embryogenesis (up to 48h following oviposition) revealed the up-regulation of sorbitol dehydrogenase upon HCl treatment, indicating increased glycogen synthesis for further embryonic development but, down-regulation of phosphofructo kinase gene expression after 18h of oviposition indicating an arrest of glycerol and sorbitol conversion. The expression of poly A binding protein gene expression was higher upon HCl treatment, revealing the initiation of translation. The expression levels of other genes analyzed did not vary significantly, except for Hsp90 and Hsp40, which were up-regulated on acid treatment until 18h. Thus, Sorbitoldehydrogenase and phosphofructo kinasegenes have a crucial role in diapause termination as evidenced by HCl treatment, while the other genes did not have major roles.