Unveiling the spatial distribution of aflatoxin B1 and plant defense metabolites in maize using AP‐SMALDI mass spectrometry imaging

SUMMARYIn order to cope with the presence of unfavorable compounds, plants can biotransform xenobiotics, translocate both parent compounds and metabolites, and perform compartmentation and segregation at the cellular or tissue level. Such a scenario also applies to mycotoxins, fungal secondary metabolites with a pre‐eminent role in plant infection. In this work, we aimed to describe the effect of the interplay between Zea mays (maize) and aflatoxin B1 (AFB1) at the tissue and organ level. To address this challenge, we used atmospheric pressure scanning microprobe matrix‐assisted laser desorption/ionization mass spectrometry imaging (AP‐SMALDI MSI) to investigate the biotransformation, localization and subsequent effects of AFB1 on primary and secondary metabolism of healthy maize plants, both in situ and from a metabolomics standpoint. High spatial resolution (5 µm) provided fine localization of AFB1, which was located within the root intercellular spaces, and co‐localized with its phase‐I metabolite aflatoxin M2. We provided a parallel visualization of maize metabolic changes, induced in different organs and tissues by an accumulation of AFB1. According to our untargeted metabolomics investigation, anthocyanin biosynthesis and chlorophyll metabolism in roots are most affected. The biosynthesis of these metabolites appears to be inhibited by AFB1 accumulation. On the other hand, metabolites found in above‐ground organs suggest that the presence of AFB1 may also activate the biochemical response in the absence of an actual fungal infection; indeed, several plant secondary metabolites known for their antimicrobial or antioxidant activities were localized in the outer tissues, such as phenylpropanoids, benzoxazinoids, phytohormones and lipids

1,3-di(benzo[d]oxazol-5-yl)urea acts as either adventitious rooting adjuvant or xylogenesis enhancer in carob and pine microcuttings depending on the presence/absence of exogenous indole-3-butyric acid

Asexual propagation in Ceratonia siliqua L. (carob), species of economic value, is difficult because of adventitious rooting recalcitrance. In Pinus radiata adventitious rooting of hypocotyl cuttings is enhanced by two urea-derivatives, 1,3-di(benzo[d]oxazol-5-yl)urea (5-BDPU) and 1,3-di(benzo[d]oxazol-6-yl)urea (6-BDPU), combined with exogenous indole-3-butyric acid (IBA). The research was aimed to define the role of these urea-derivatives in adventitious root (AR) formation of carob, and to identify morphogenic roles induced in carob, but also in pine, a distantly-related forest species. In carob, 5-BDPU (10 μM) highly promoted AR formation in combination with IBA (1 μM) when applied for 3 days, followed by a transfer onto hormone free medium (HF) up to culture end (4 weeks). IBA alone (1 μM) was more effective than IBA + kinetin (Kin, 10 nM), whereas Kin alone and 5-BDPU alone were not AR-inductive. The histological analysis showed that the cambial cells initiated the ARs, and similar numbers of AR-primordia were visible at day 12, independently of the AR-inductive treatment (i.e., IBA, IBA + 5-BDPU, IBA + Kin). No cutting treated with Kin alone, and rare HF (±5-BDPU)-treated ones, showed AR-primordia at day 12. The number of AR-forming explants increased under IBA + 5-BDPU. By contrast, the cambial cells were stimulated to initiate deuteroxylem instead of ARs under 5-BDPU alone. The histological analysis in pine microcuttings treated with IBA and/or 5-BDPU at the same concentrations confirmed that 5-BDPU applied alone enhanced xylogenesis, highlighting that this urea-derivative exhibits a dual morphogenic role being involved in the switching between adventitious rooting and xylogenesis depending on the presence of exogenous auxin in both species

Mortality and pulmonary complications in patients undergoing surgery with perioperative SARS-CoV-2 infection: an international cohort study

Background: The impact of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) on postoperative recovery needs to be understood to inform clinical decision making during and after the COVID-19 pandemic. This study reports 30-day mortality and pulmonary complication rates in patients with perioperative SARS-CoV-2 infection. Methods: This international, multicentre, cohort study at 235 hospitals in 24 countries included all patients undergoing surgery who had SARS-CoV-2 infection confirmed within 7 days before or 30 days after surgery. The primary outcome measure was 30-day postoperative mortality and was assessed in all enrolled patients. The main secondary outcome measure was pulmonary complications, defined as pneumonia, acute respiratory distress syndrome, or unexpected postoperative ventilation. Findings: This analysis includes 1128 patients who had surgery between Jan 1 and March 31, 2020, of whom 835 (74·0%) had emergency surgery and 280 (24·8%) had elective surgery. SARS-CoV-2 infection was confirmed preoperatively in 294 (26·1%) patients. 30-day mortality was 23·8% (268 of 1128). Pulmonary complications occurred in 577 (51·2%) of 1128 patients; 30-day mortality in these patients was 38·0% (219 of 577), accounting for 81·7% (219 of 268) of all deaths. In adjusted analyses, 30-day mortality was associated with male sex (odds ratio 1·75 [95% CI 1·28–2·40], p\textless0·0001), age 70 years or older versus younger than 70 years (2·30 [1·65–3·22], p\textless0·0001), American Society of Anesthesiologists grades 3–5 versus grades 1–2 (2·35 [1·57–3·53], p\textless0·0001), malignant versus benign or obstetric diagnosis (1·55 [1·01–2·39], p=0·046), emergency versus elective surgery (1·67 [1·06–2·63], p=0·026), and major versus minor surgery (1·52 [1·01–2·31], p=0·047). Interpretation: Postoperative pulmonary complications occur in half of patients with perioperative SARS-CoV-2 infection and are associated with high mortality. Thresholds for surgery during the COVID-19 pandemic should be higher than during normal practice, particularly in men aged 70 years and older. Consideration should be given for postponing non-urgent procedures and promoting non-operative treatment to delay or avoid the need for surgery. Funding: National Institute for Health Research (NIHR), Association of Coloproctology of Great Britain and Ireland, Bowel and Cancer Research, Bowel Disease Research Foundation, Association of Upper Gastrointestinal Surgeons, British Association of Surgical Oncology, British Gynaecological Cancer Society, European Society of Coloproctology, NIHR Academy, Sarcoma UK, Vascular Society for Great Britain and Ireland, and Yorkshire Cancer Research

Effects of diphenylurea derivatives on adventitious rooting

Adventitious root formation is a key step in vegetative propagation of plants, one of the most efficient methods to multiply plants in vivo or in vitro. Endogenous auxin (namely indole 3 acetic acid, IAA) has been established as natural inducer of root formation, and its capacity to induce roots when exogenously applied has also been rapidly recognised. However, in the case of woody plants there is often a physiological inability to produce adventitious roots even after external supplementation of auxins, either natural or synthetic. Despite the huge commercial interest and the large number of attempts, auxin alone has proved to be not sufficient to induce root formation in so called difficult to root species. Different strategies have therefore been implemented with a view to improving adventitious rooting: treatment with any kind of plant growth regulators; supplementation of non hormonal compounds such as polyamines, phenolic compounds, thiol compounds; use of Agrobacterium rhizogenes as root inducing bacterium. Considering broad interest in the area of nonhormonal bioactive compound supplementation, in this chapter we summarize the effects of some diphenylurea derivatives as “rooting adjuvants”, since they markedly enhance rooting when applied alone or in combination with auxins

An optimized method for in vitro propagation of African baobab (Adansonia digitata L.) using two-node segments

Adansonia digitata L. (African baobab), is an important multi-purpose tree, whose distribution is at present limited to wild or semi-domesticated individuals widespread in Africa. Its distribution is threatened by seedling clearance for other land use and potentially by overharvesting induced by growing commercial use of baobab fruit. Recently, efforts have been made to establish baobab domestication and conservation strategies, with mixed results due to the low germinability of baobab seeds, a factor that hinders the possibility of developing commercial A. digitata plantations. Here, micropropagation was tested as a method for clonal propagation of explants from in vivo-grown seedlings. In vitro shoot multiplication was achieved by enhanced axillary bud proliferation of sterilized two-node segments. Bud break was dependent on cytokinin supply, but the combination of 1.0 or 10.0 μM zeatin riboside and 10.0 μM indole-3-butyric acid (IBA) increased the formation of microshoots after 8 weeks of culture. Regenerated microshoots rooted successfully in in vitro nutrient medium containing 10.0 μM IBA and normally grew in a greenhouse after acclimatization

Organogenesi somatica in vitro

Le piante sono organismi affascinanti in grado di percepire prontamente stimoli endogeni ed ambientali, integrarli e reagire con una rete complessa di risposte fisiologiche. Il concepimento di metodiche innovative di laboratorio è fondamentale per migliorare la conoscenza di questi processi e ideare strategie utili in molteplici settori, come la moderna agricoltura sostenibile e la bioenergia. FISIOLOGIA VEGETALE APPLICATA a cura di Vincenzo Lionetti e Daniela Bellincampi, forti della loro lunga esperienza in campo didattico, sono riusciti a scrivere un testo che sarà di grande aiuto agli studenti e, perché no, anche a curiosi e appassionati, per l’attività pratica di ricerca in laboratorio e per approfondire le procedure analitiche alla base degli studi attuali più rilevanti nel campo della Fisiologia vegetale, curando vari aspetti come la biologia cellulare, la biologia molecolare, la biochimica, l’elettrofisiologia, l’ingegneria genetica e varie applicazioni biotecnologiche. I contenuti sono stati adeguati alle esigenze dei recenti ordinamenti didattici dei corsi di laurea in Scienze biologiche, in Biotecnologie e in Agraria

N,N'-bis-(2,3-methylenedioxyphenyl)urea and N,N'-bis-(3,4-methylenedioxyphenyl)urea enhance adventitious rooting in Pinus radiata and affect expression of genes induced during adventitious rooting in the presence of exogenous auxin

We have analyzed the effect of N,N′-bis-(2,3-methylenedioxyphenyl)urea (2,3-MDPU) and N,N′-bis-(3,4-methylenedioxyphenyl)urea (3,4-MDPU), two symmetrically substituted diphenylurea derivatives with no auxin or cytokinin-like activity, on the rooting capacity of Pinus radiata stem cuttings. Results indicate that both diphenylurea derivatives enhance adventitious rooting in the presence of exogenous auxin (indole-3-butyric acid, IBA), even at low auxin concentration, in rooting-competent cuttings, but have no effect on the adventitious rooting of low or null competent-to-root cuttings. Histological analyses show that, in the simultaneous presence of MDPUs and low concentration of exogenous auxin, adventitious root formation is induced in the cell types that retain intrinsic competence to form adventitious roots in response to auxin. The time course of cellular events leading to root formation and the time of root emergence are closely similar to that observed in cuttings treated only with higher auxin concentration. In addition, the mRNA level of a P. radiata SCARECROW-LIKE gene, which is significantly induced in the presence of the optimal concentration (10 μM) of exogenous auxin needed for cuttings to root, is increased in the presence of MDPUs and low concentration of exogenous auxin (1 μM). The expression of a P. radiata SHORT-ROOT gene in rooting-competent cuttings during adventitious rooting is also affected by the presence of MDPUs when combined with auxin. As MDPUs do not affect the expression of either gene in the absence of exogenous auxin, but only in its presence, we suggest that MDPUs could interact, directly or indirectly, with the auxin-signalling pathways in rooting-competent cuttings during adventitious rooting