Plant Cellular and Molecular Biotechnology: Following Mariotti's Steps

This review is dedicated to the memory of Prof. Domenico Mariotti, who significantly contributed to establishing the Italian research community in Agricultural Genetics and carried out the first experiments of Agrobacterium-mediated plant genetic transformation and regeneration in Italy during the 1980s. Following his scientific interests as guiding principles, this review summarizes the recent advances obtained in plant biotechnology and fundamental research aiming to: (i) Exploit in vitro plant cell and tissue cultures to induce genetic variability and to produce useful metabolites; (ii) gain new insights into the biochemical function of Agrobacterium rhizogenes rol genes and their application to metabolite production, fruit tree transformation, and reverse genetics; (iii) improve genetic transformation in legume species, most of them recalcitrant to regeneration; (iv) untangle the potential of KNOTTED1-like homeobox (KNOX) transcription factors in plant morphogenesis as key regulators of hormonal homeostasis; and (v) elucidate the molecular mechanisms of the transition from juvenility to the adult phase in Prunus tree species

Insights into the Sesquiterpenoid Pathway by Metabolic Profiling and De novo Transcriptome Assembly of Stem-Chicory (Cichorium intybus Cultigroup "Catalogna")

Stem-chicory of the "Catalogna" group is a vegetable consumed for bitter-flavored stems. Type and levels of bitter sesquiterpene lactones (STLs) participate in conferring bitterness in vegetables. The content of lactucin-and lactucopocrin-like STLs was higher in "Molfettese" than "Galatina" landrace stalks, regardless of the cultivation sites, consistently with bitterness scores and gustative differences. The "Galatina" transcriptome assembly resulted in 58,872 unigenes, 77% of which were annotated, paving the way to molecular investigation of the STL pathway. Comparative transcriptome analysis allowed the identification of 69,352 SNPs and of 1640 differentially expressed genes that maintained the pattern independently of the site. Enrichment analyses revealed that 4 out of 29 unigenes were up-regulated in "Molfettese" vs "Galatina" within the sesquiterpenoid pathway. The expression of two germacrene A -synthase (GAS) and one -oxidase (GAO) genes of the costunolide branch correlated positively with the contents of lactucin-like molecules, supporting that STL biosynthesis regulation occurs at the transcriptional level. Finally, 46 genes encoding transcription factors (TFs) maintained a differential expression pattern between the two varieties regardless of the growth site; correlation analyses among TFs, GAS, GAO gene expressions and STLs contents suggest that one MYB and one bHLH may act in the pathway

Phytotoxic impact of bifunctionalized silver nanoparticles (AgNPs-Cit-L-Cys) and silver nitrate (AgNO3) on chronically exposed callus cultures of Populus nigra L

Owing to the unique physicochemical properties and the low manufacturing costs, silver nanoparticles (AgNPs) have gained growing interest and their application has expanded considerably in industrial and agricultural sectors. The large-scale production of these nanoparticles inevitably entails their direct or indirect release into the environment, raising some concerns about their hazardous aspects. Callus culture represents an important tool in toxicological studies to evaluate the impact of nanomaterials on plants and their potential environmental risk. In this study, we investigated the chronic phytotoxic effects of different concentrations of novel bifunctionalized silver nanoparticles (AgNPs-Cit-L-Cys) and silver nitrate (AgNO3) on callus culture of Populus nigra L., a pioneer tree species in the riparian ecosystem. Our results showed that AgNPs-Cit-L-Cys were more toxic on poplar calli compared to AgNO3, especially at low concentration (2.5 mg/L), leading to a significant reduction in biomass production, accompanied by a decrease in protein content, a significant increase in both lipid peroxidation level, ascorbate peroxidase (APX), and catalase (CAT) enzymatic activities. In addition, these findings suggested that the harmful activity of AgNPs-Cit-L-Cys might be correlated with their physicochemical properties and not solely attributed to the released Ag+ ions and confirmed that AgNPs-Cit-L-Cys phytoxicity is associated to oxidative stress

A Novel Role of <i>Medicago truncatula</i> KNAT3/4/5-like Class 2 KNOX Transcription Factors in Drought Stress Tolerance

Class 2 KNOX homeobox transcription factors (KNOX2) play a role in promoting cell differentiation in several plant developmental processes. In Arabidopsis, they antagonize the meristematic KNOX1 function during leaf development through the modulation of phytohormones. In Medicago truncatula, three KNOX2 genes belonging to the KNAT3/4/5-like subclass (Mt KNAT3/4/5-like or MtKNOX3-like) redundantly works upstream of a cytokinin-signaling module to control the symbiotic root nodule formation. Their possible role in the response to abiotic stress is as-of-yet unknown. We produced transgenic M. truncatula lines, in which the expression of four MtKNOX3-like genes was knocked down by RNA interference. When tested for response to water withdrawal in the soil, RNAi lines displayed a lower tolerance to drought conditions compared to the control lines, measured as increased leaf water loss, accelerated leaf wilting time, and faster chlorophyll loss. Reanalysis of a transcriptomic M. truncatula drought stress experiment via cluster analysis and gene co-expression networks pointed to a possible role of MtKNOX3-like transcription factors in repressing a proline dehydrogenase gene (MtPDH), specifically at 4 days after water withdrawal. Proline measurement and gene expression analysis of transgenic RNAi plants compared to the controls confirmed the role of KNOX3-like genes in inhibiting proline degradation through the regulation of the MtPDH gene

Effects of Microplastic Contamination on the Aquatic Plant <i>Lemna minuta</i> (Least Duckweed)

Microplastics are widely spread in aquatic environments. Although they are considered among the most alarming contaminants, toxic effects on organisms are unclear, particularly on freshwater plants. In this study, the duckweed Lemna minuta was grown on different concentrations (50, 100 mg/L) of poly(styrene-co-methyl methacrylate) microplastics (MP) and exposure times (T0, T7, T14, T28 days). The phytotoxic effects of MP were investigated by analyzing several plant morphological and biochemical parameters (frond and root size, plant growth, chlorophyll, and malondialdehyde content). Observations by scanning electron microscope revealed MP adsorption on plant surfaces. Exposition to MP adversely affected plant growth and chlorophyll content with respect to both MP concentrations and exposure times. Conversely, malondialdehyde measurements did not indicate an alteration of oxidative lipid damage in plant tissue. The presence of MP induced root elongation when compared to the control plants. The effects of MP on L. minuta plants were more evident at T28. These results contribute to a better understanding of MP’s impact on aquatic plants and highlight that MP contamination manifests with chronic-type effects, which are thus detectable at longer exposure times of 7 days than those traditionally used in phytotoxicology tests on duckweeds

A New Testing Facility to Investigate the Removal Processes of Indoor Air Contaminants with Different Cleaning Technologies and to Better Assess and Exploit Their Performances

Residential air cleaners exploiting different technologies re commonly used today to remove air contaminants from indoor environments. Different methods have been developed in the USA and Europe to test their efficiency. The one used in the USA provides a more comprehensive view of indoor processes, because testing is performed in a large simulation chamber (28.5 m3), using anthropogenic emissions, such as cigarette smoke, to generate pollution. Testing rooms are also important to investigate new removal technologies, or to improve them. Since no such testing facilities exist in Italy, one of 12.4 m3 was built in which cigarette smoke, resuspended dust from agricultural soil and, for the first time, diesel exhaust emissions were used to generate indoor pollution. Performances were tested with two air cleaning systems, exploiting completely different removal technologies. Accurate values of decay rates of indoor pollutants were obtained using a suite of on-line and out-of-line monitors for the measurement of particulate matter, volatile organic compounds (VOCs) and some inorganic gases. Proton-transfer mass spectrometry (PTR-MS) provided an almost real-time detection of several VOCs and H2S, at trace levels (0.01 ppbv). A method using a common in vitro bioassay was developed to assess the ability of air cleaners to remove indoor toxic substances

A New Testing Facility to Investigate the Removal Processes of Indoor Air Contaminants with Different Cleaning Technologies and to Better Assess and Exploit Their Performances

Residential air cleaners exploiting different technologies re commonly used today to remove air contaminants from indoor environments. Different methods have been developed in the USA and Europe to test their efficiency. The one used in the USA provides a more comprehensive view of indoor processes, because testing is performed in a large simulation chamber (28.5 m3), using anthropogenic emissions, such as cigarette smoke, to generate pollution. Testing rooms are also important to investigate new removal technologies, or to improve them. Since no such testing facilities exist in Italy, one of 12.4 m3 was built in which cigarette smoke, resuspended dust from agricultural soil and, for the first time, diesel exhaust emissions were used to generate indoor pollution. Performances were tested with two air cleaning systems, exploiting completely different removal technologies. Accurate values of decay rates of indoor pollutants were obtained using a suite of on-line and out-of-line monitors for the measurement of particulate matter, volatile organic compounds (VOCs) and some inorganic gases. Proton-transfer mass spectrometry (PTR-MS) provided an almost real-time detection of several VOCs and H2S, at trace levels (0.01 ppbv). A method using a common in vitro bioassay was developed to assess the ability of air cleaners to remove indoor toxic substances

Transcriptome driven characterization of curly- and smooth-leafed endives reveals molecular differences in the sesquiterpenoid pathway

Diving into the genetics of endives Genetic analyses show molecular differences that could explain why curly endives taste bitterer than smooth ones. Donato Giannino of the Institute of Agricultural Biology and Biotechnology and colleagues in Italy analyzed the genetic differences between curly and smooth endives, a leafy vegetable used in salads. They found more than 3000 single sequence variations in genes distinguishing the two types from each other. Twenty six genes were involved in the biosynthesis of sesquiterpenoids, metabolites important for plant survival that also contribute to the bitter taste of endives and have antimalarial, sedative and analgesic effects when isolated for humans. Their levels were higher in curly than in smooth endives, potentially contributing to their more bitter taste. The information expands the genetic data available on endives for breeding programs

Nocturnal haemodialysis is associated with a reduced occurrence of low triiodothyronine serum levels in haemodialysed patients

Background End-stage renal disease (ESRD) is associated with a broad spectrum of morphological and functional thyroid disorders. Recent studies have shown that low free triiodothyronine (fT3) levels are related to inflammatory status and endothelial activation in ESRD patients on haemodialysis (HD). Limited data exist about a possible relationship between dialysis regimen, namely long nocturnal haemodialysis (LNHD), and thyroid function parameters. The aim of this study was to evaluate the relationship between dialysis regimen and thyroid function, and consequently with the main patient outcomes. Methods To this purpose, we performed a retrospective, single-centre cohort study including 220 incident chronic HD patients treated during an 8-year period (from January 2010 to December 2017). The main clinical and haematochemical parameters, including thyroid function, were evaluated and related to the main patient outcomes. Results Patients with low fT3 levels (&lt;3.05 ng/mL) showed significantly lower survival rates than patients with normal fT3 levels (&gt;3.05 ng/mL) (P &lt; 0.001), although there were no substantial differences in the demographic and clinical characteristics between the two groups. After propensity score 1:3 matching of 25 patients treated with nocturnal HD to 75 patients treated with diurnal HD, LNHD patients showed significantly higher survival rates (88.0% versus 61.3%, P = 0.001) and lower incidence of cardiovascular events than patients on diurnal dialysis (8.0% versus 40.0%, P = 0.001). Moreover, an 8-year time-dependent analysis showed that at any time, except for baseline, the rate of patients with fT3 levels &gt;3.05 ng/mL was significantly higher in LNHD patients than in patients treated with diurnal dialysis. Conclusions Our data suggest that the application of alternative dialysis regimens, also reducing the frequency of low T3, could ameliorate outcomes and therefore reduce the incidence of cardiovascular events in HD patients