Andrea Ghirardo

• Dr.
• Group Leader at Helmholtz Zentrum München Deutsches Forschungszentrum für Gesundheit und Umwelt (GmbH)

Azolla spp. are floating ferns used for centuries as biofertilizers to enrich the soil with inorganic nitrogen and improve rice yields. However, the molecular interactions between Azolla and co-cultivated rice plants only recently started to be thoroughly investigated. In this study, we exploited an experiment in which rice plants were grown togeth...

In order to predict the future of European forests, it is crucial to assess the potential of the dominant perennial species to adapt to rapid climate change. The aim of this study was to reconstruct the pattern of distribution of drought tolerance in Quercus robur in the current center of the species' range. The distribution and plasticity of droug...

Like other plant-microbe symbioses, the establishment of orchid mycorrhiza (ORM) is likely to require specific communication and metabolic adjustments between the two partners. However, while modulation of plant and fungal metabolism has been investigated in fully established mycorrhizal tissues, the molecular changes occurring during the pre-symbi...

Isoprene, the most abundant hydrocarbon emitted by vegetation, protects photosynthesis against oxidative and thermal stress and significantly impacts atmospheric chemistry. While laboratory studies suggest a role for isoprene in plant defense, its function in plant-plant communication under natural conditions remains unclear. Here, we demonstrate t...

Isoleucic acid (ILA) was identified in human patients with maple syrup urine disease (MSUD) half a century ago. MSUD patients, who are defective in the catabolism of branched‐chain amino acids (BCAAs), that is, isoleucine, leucine, and valine, have urine with a unique maple syrup odour related to the accumulation of BCAA breakdown products, largely...

The barley powdery mildew disease caused by the biotrophic fungus Blumeria hordei (Bh) poses enormous risks to crop production due to yield and quality losses. Plants and fungi can produce and release volatile organic compounds (VOCs) that serve as signals in plant communication and defense response to protect themselves. The present study aims to...

In nature, germination of orchid seeds and early plant development rely on a symbiotic association with orchid mycorrhizal (ORM) fungi. These fungi provide the host with the necessary nutrients and facilitate the transition from embryos to protocorms. Despite recent advances in omics technologies, our understanding of this symbiosis remains limited...

Azolla spp. are floating ferns used for centuries as biofertilizers to enrich the soil with inorganic nitrogen and improve rice yields. In this study, rice plants were grown together with Azolla by maintaining a low and constant concentration of inorganic nitrogen. We employed a combination of non-targeted metabolomics, chemometrics, and molecular...

With over 250 known species, the genus Trichoderma (Ascomycota, Hypocreaceae) is found in various soils, on plant surfaces and as plant endophytes. While Trichoderma species are known as mycoparasites, their antagonistic behaviour can also negatively affect other beneficial fungi, such as mycorrhizal fungi. To gain insight into the metabolic signal...

Plants are central to complex networks of multitrophic interactions. Increasing evidence suggests that beneficial microorganisms (BMs) may be used as plant biostimulants and pest biocontrol agents. We investigated whether tomato (Solanum lycopersicum) plants are thoroughly colonized by the endophytic and entomopathogenic fungus Beauveria bassiana,...

Metabolomics studies are becoming increasingly common for understanding how plant metabolism responds to changes in environmental conditions, genetic manipulations, and treatments. Despite the recent advances in metabolomics workflow, the sample preparation process still limits the high-throughput analysis in large-scale studies. Here, we present a...

Defense responses in plants are based on complex biochemical processes. Systemic acquired resistance (SAR) helps to fight infections by (hemi-)biotrophic pathogens. One important signaling molecule in SAR is pipecolic acid (Pip), accumulation of which is dependent on the aminotransferase ALD1 in Arabidopsis thaliana. While exogenous Pip primes defe...

Plants harbour a wide range of leaf‐feeding insects whose survival and fitness are influenced by both energy‐rich molecules and phytochemicals in the host foliage. Yet, how leaf host chemical diversity and insect microbiota—key factors in ecological and physiological processes—impact insect nutrition and fitness are still poorly understood. To stud...

Sesquiterpenes (STs) are secondary metabolites, which mediate biotic interactions between different organisms. Predicting the species-specific ST repertoires can contribute to deciphering the language of communication between organisms of the same or different species. High biochemical plasticity and catalytic promiscuity of sesquiterpene synthases...

Isoprene-emitting plants are better protected against thermal and oxidative stresses, which is a desirable trait in a climate-changing (drier and warmer) world. Here we compared the ecophysiological performances of transgenic isoprene-emitting and wild-type non-emitting tobacco plants during water stress and after re-watering in actual environmenta...

Ongoing global warming favors the spread of thermo-tolerant plant species including plants with a high allergenic risk such as common ragweed (Ambrosia artemisiifolia). To assess effects of temperature increase on plant traits and biochemical processes potentially associated with allergenicity, we performed a phytotron chamber experiment which incl...

Endophytic colonization by B. bassiana strain ATCC 74040 (Naturalis®) helps plant fight Botrytis cinerea infection.

Plants harbor a wide range of leaf-feeding insects. Insect survival and fitness are influenced by both energy-rich molecules and phytochemicals in the host foliage. Yet, how leaf chemical diversity and insect microbiota - key factors in ecological and physiological processes – shape insect nutrition and impact insect performance is still poorly und...

Air chemistry is affected by the emission of biogenic volatile organic compounds (BVOCs), which originate from almost all plants in varying qualities and quantities. They also vary widely among different crops, an aspect that has been largely neglected in emission inventories. In particular, bioenergyrelated species can emit mixtures of highly reac...

Biogenic volatile organic compounds (BVOC) play important roles in plant stress responses and can serve as stress indicators. While the impacts of gradual environmental changes on BVOCs have been studied extensively, insights in emission responses to repeated stress and recovery are widely absent. Therefore, we studied the dynamics of shoot gas exc...

Climate change is increasing the frequency and intensity of warming and drought periods around the globe, currently representing a threat to many plant species. Understanding the resistance and resilience of plants to climate change is, therefore, urgently needed. As date palm (Phoenix dactylifera) evolved adaptation mechanisms to a xeric environme...

Plants activate biochemical responses to combat stress. (Hemi-)biotrophic pathogens are fended off by systemic acquired resistance (SAR), a primed state allowing plants to respond faster and stronger upon subsequent infection. Here, we show that SAR-like defences in barley (Hordeum vulgare) are propagated between neighboring plants, which respond w...

Climate change is increasing insect pressure and forcing plants to adapt. Although chemotypic differentiation and phenotypic plasticity in spatially separated tree populations are known for decades, understanding their importance in herbivory resistance across forests remains challenging. We studied four oak forest stands in Germany using nontarget...

Fungi produce a wide variety of volatile organic compounds (VOCs), which play central roles in the initiation and regulation of fungal interactions. Here we introduce a global overview of fungal VOC patterns and chemical diversity across phylogenetic clades and trophic modes. The analysis is based on measurements of comprehensive VOC profiles of fo...

Nitric oxide (NO) is a signaling molecule with multiple regulatory functions in plant physiology and stress response. In addition to direct effects on transcriptional machinery, NO executes its signaling function via epigenetic mechanisms. We report that light intensity-dependent changes in NO correspond to changes in global histone acetylation (H3...

Climate change is increasing the frequency and intensity of warming and drought periods around the globe, currently representing a threat to many plant species. Understanding the resistance and resilience of plants to climate change is, therefore, urgently needed. As date palm (Phoenix dactylifera) evolved adaptation mechanisms to a xeric environme...

Isoprene and other terpenoids are important biogenic volatile organic compounds in terms of atmospheric chemistry. Isoprene can aid plant performance under abiotic stresses, but the fundamental biological reasons for the high emissions are not completely understood. Here, we provide evidence of a previously unrecognized ecological function for isop...

Ecosystems integrity and services are threatened by anthropogenic global changes. Mitigating and adapting to these changes require knowledge of ecosystem functioning in the expected novel environments, informed in large part through experimentation and modelling. This paper describes 13 advanced controlled environment facilities for experimental ec...

The development of light-emitting diodes (LEDs) of different emission spectra is revolutionizing lighting technology and opening up completely new applications and research areas. The spectral irradiance of the sun reaching the Earth's surface is very complex due to radiative transfer processes within the atmosphere and ranges from the shortwave ul...

Nitrogen oxides (NOx), mainly a mixture of nitric oxide (NO) and nitrogen dioxide (NO2), are formed by the reaction of nitrogen and oxygen compounds in the air as a result of combustion processes and traffic. Both deposit into leaves via stomata, which on the one hand benefits air quality and on the other hand provides an additional source of nitro...

All orchids rely on mycorrhizal fungi for organic carbon, at least during early development. In fact, orchid seed germination leads to the formation of a protocorm, a heterotrophic postembryonic structure colonized by intracellular fungal coils, thought to be the site of nutrient transfer. The molecular mechanisms underlying mycorrhizal interaction...

[This corrects the article DOI: 10.3389/fpls.2018.00766.].

Isoprene is a C5 volatile organic compound, which can protect aboveground plant tissue from abiotic stress such as short‐term high temperatures and accumulation of reactive oxygen species (ROS). Here, we uncover new roles for isoprene in the plant belowground tissues. By analysing Populus x canescens isoprene synthase (PcISPS) promoter reporter pla...

Nitric oxide (NO) is a signaling molecule with multiple regulatory functions in plant physiology and stress response. Besides direct effects on the transcriptional machinery, NO can fulfill its signaling function via epigenetic mechanisms. We report that light intensity-dependent changes in NO correlate with changes in global histone acetylation (H...

Volatile organic compounds (VOCs) play vital roles in the interaction of fungi with plants and other organisms. A systematic study of the global fungal VOC profiles is still lacking, though it is a prerequisite for elucidating the mechanisms of VOC‐mediated interactions. Here we present a versatile system enabling a high‐throughput screening of fun...

Isoleucic acid (ILA ), a branched-chain amino acid-related 2-hydroxy carboxylic acid, occurs ubiquitously in plants. ILA enhances pathogen resistance and inhibits root growth of Arabidopsis thaliana. The salicylic acid (SA) glucosyltransferase UGT76B1 is able to conjugate ILA as well. Here, we investigate the role of ILA in planta and reveal a tria...

Warming occurs in the Arctic twice as fast as the global average, which in turn leads to a large enhancement in terpenoid emissions from vegetation. Volatile terpenoids are the main class of biogenic volatile organic compounds (VOCs) that play crucial roles in atmospheric chemistry and climate. However, the biochemical mechanisms behind the tempera...

Salicylic acid (SA)-mediated innate immune responses are activated in plants perceiving volatile monoterpenes. Here, we show that monoterpene-associated responses are propagated in feed-forward loops involving the systemic acquired resistance (SAR) signaling components pipecolic acid, glycerol-3-phosphate, and LEGUME LECTIN-LIKE PROTEIN1 (LLP1). In...

We studied acclimation of leaf gas exchange to differing seasonal climate and soil water availability in slow‐growing date palm (Phoenix dactylifera) seedlings. We used an extended Arrhenius equation to describe instantaneous temperature responses of leaf net photosynthesis (A) and stomatal conductance (G), and derived physiological parameters suit...

To investigate the effect of high atmospheric NO concentrations on crop plants and the role of phytoglobins under these conditions, we performed a long-term study on barley 'Golden Promise' wild type (WT), class 1 phytoglobin knockdown (HvPgb1.1-) and class 1 phytoglobin overexpression (HvPgb1.1+) lines. Plants were cultivated with nitrogen-free nu...

The emission of biogenic volatile organic compounds (BVOCs) is usually thought to depend on species-specific emission capacities that vary with seasonal and phenological conditions. Actual-so called constitutive-emissions are then calculated from prevailing temperature and radiation. However, various abiotic and biotic stressors such as ozone, extr...

Fungi of the genus Trichoderma are economically important due to their plant growth- and performance-promoting effects, such as improved nutrient supply, mycoparasitism of plant-pathogens and priming of plant defense. Due to their mycotrophic lifestyle, however, they might also be antagonistic to other plant-beneficial fungi, such as mycorrhiza-for...

The emissions of BVOCs from oilseed rape (Brassica napus), both when the plant is exposed to clean air and when it is fumigated with ozone at environmentally-relevant mixing ratios (ca. 135 ppbv), were measured under controlled laboratory conditions. Emissions of BVOCs were recorded from combined leaf and root chambers using a recently developed Se...

Seasonal variations in monoterpene emissions from Scots pine (Pinus sylvestris) are well documented, and emissions are often shown to follow the incident temperatures due to effects on compound volatility. Recent studies have indicated a link between monoterpene emissions and physiological drivers such as photosynthetic capacity during needle devel...

Nitrogen dioxide (NO2) forms in plants under stress conditions, but little is known about its physiological functions. Here, we explored the physiological functions of NO2 in plant cells using short-term fumigation of Arabidopsis (Arabidopsis thaliana) for 1 h with 10 parts per million (ppm) NO2. Although leaf symptoms were absent, the expression o...

Vegetation in the Arabian Peninsula is facing high and steadily rising tropospheric ozone pollution. However, little is known about the impacts of elevated ozone on date palms, one of the most important indigenous economic species. To elucidate the physiological responses of date palm to peak levels of acute ozone exposure, seedlings were fumigated...

The branched-chain amino acid (BCAA) related 2-hydroxy carboxylic acid isoleucic acid (ILA) enhances salicylic acid-mediated pathogen defense in Arabidopsis thaliana. ILA has been identified in A. thaliana as its glucose conjugate correlated with the activity of the small-molecule glucosyltransferase UGT76B1, which can glucosylate both salicylic ac...

Indoor pollution poses a serious threat to human health. Plants represent a sustainable but underexploited solution to enhance indoor air quality. However, the current selection of plants suitable for indoors fails to consider the physiological processes and mechanisms involved in phytoremediation. Therefore, the capacity of plants to remove indoor...

Seasonal variations in monoterpene emissions from Scots pine (Pinus sylvestris) are well documented, and emissions are often shown to follow the incident temperatures due to effects on compound volatility. Recent studies have indicated a link between monoterpene emissions and physiological drivers such as photosynthetic capacity during needle devel...

For avoiding competition with food production, marginal land is economically and environmentally highly attractive for biomass production with short-rotation coppices (SRC) of fast-growing tree species such as poplars. Herein, we evaluated the environmental impacts of technological, agronomic and environmental aspects of bioenergy production from h...

This study investigates the role of volatile organic compounds in systemic acquired resistance (SAR), a salicylic acid (SA)-associated, broad-spectrum immune response in systemic, healthy tissues of locally infected plants. Gas chromatography coupled to mass spectrometry analyses of SAR-related emissions of wild-type and non-SAR-signal-producing mu...

Bioenergy crop production is rapidly expanding in Europe and the potential emissions of biogenic volatile organic compounds (BVOCs) might change the chemical composition of the atmosphere, influencing in turn air quality and regional climate. The environmental impacts of bioenergy crops on air chemistry are difficult to assess due to a lack of accu...

Background and aimsIsoprene and monoterpenes account for approximately two thirds of the biogenic volatile organic compounds (BVOC) emitted annually by vegetation into the atmosphere. Previous research focussed on the magnitude of and controls on emissions of these two compounds by emitting plant species, while the role of soils and non-emitting pl...

By avoiding competition with classical agricultural production marginal land is economically and environmentally highly attractive for biomass production with short-rotations coppices (SRC) of fast-growing tree species such as poplars. The quantification of carbon sequestration and the comparable evaluation of potential environmental impacts are b...

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Trees can significantly impact the urban air chemistry by the uptake and emission of reactive biogenic volatile organic compounds (BVOCs), which are involved in ozone and particle formation. Here we present the emission potentials of "constitutive" (cBVOCs) and "stress-induced" BVOCs (sBVOCs) from the dominant broadleaf woody plant species in the m...

Alternaria alternata is one of the most studied fungi to date because of its impact on human life – from plant pathogenicity to allergenicity. However, its sesquiterpene emissions have not been systematically explored. Alternaria regularly co-occurs with Fusarium fungi, which are common plant pathogens, on withering plants. We analyzed the diversit...

Germany, and other countries as well, intends to largely increase the plantation area for bioenergy production in the near future. Potential plant species that are likely to be intensively cultivated are corn, energy grasses, and woody crops, which might emit biogenic volatile organic compounds (BVOC) at higher rates than common agricultural specie...

Researchers have been examining the biological function(s) of isoprene in isoprene-emitting species for two decades. There is overwhelming evidence that leaf-internal isoprene increases the thermo-tolerance of plants and protects them against oxidative stress, thus mitigating a wide range of abiotic stresses. However, the mechanisms of abiotic stre...

Over the last decades, post illumination bursts (PIBs) of isoprene, acetaldehyde and green leaf volatiles (GLVs) following rapid light-to-dark transitions have been reported for a variety of different plant species. However, the mechanisms triggering their release still remain unclear. Here we measured PIBs of isoprene emitting (IE) and isoprene no...