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Chloroplast movement rapidly ameliorates the effects of suboptimal light intensity by accumulating along the periclinal cell walls, as well as the effects of excess light by shifting to the anticlinal cell walls. These acclimation responses are triggered by phototropins located at the plasma membrane and chloroplast envelope. Here, we used a recently developed non-invasive system sensitive to very small changes in red light leaf transmittance to perform long-term continuous measurements of dark–light transitions. As a model system, we used variegated Pelargonium zonale leaves containing green sectors (GS) with fully developed chloroplasts and achlorophyllous, white sectors (WS) with undifferentiated plastids, and higher phototropin expression levels. We observed biphasic changes in the red-light transmittance and oscillations triggered by medium intensities of white light, described by a transient peak preceded by a constant decrease in transmittance level. A slight change in red-light transmittance was recorded even in WS. Furthermore, the chloroplast position at lower light intensities affected the rapid light curves, while high light intensity decreased saturated electron transport, maximum quantum efficiency of photosystem II, and increased non-photochemical quenching of chlorophyll fluorescence and epidermal flavonoids. Our results extend the knowledge of light-dependent chloroplast movements and thus contribute to a better understanding of their role in regulating photosynthesis under fluctuating light conditions.

Three basil plant varieties (Ocimum basilicum var. Genovese, Ocimum x citriodorum, and Ocimum basilicum var. purpurascens) were grown under moderate light (about 300 umol photons m-2 s-1) in a glasshouse or growth chamber and then either transferred to an open field (average daily dose: 29.2 kJ m-2 d-1) or additionally exposed to UV-B irradiation in a growth chamber (29.16 kJ m-2 d-1), to reveal the variety-specific and light-specific acclimation responses. Total antioxidant capacity (TAC), phenolic profile, ascorbate content, and class III peroxidase (POD) activity were used to determine the antioxidant status of leaves under all four light regimes. Exposure to high solar irradiation at the open field resulted in an increase in TAC, total hydroxycinnamic acids (HCAs, especially caffeic acid), flavonoids, and epidermal UV-absorbing substances in all three varieties, as well as a two-fold increase in the leaf dry/fresh weight ratio. The supplemental UV-B irradiation induced preferential accumulation of HCAs (rosmarinic acid) over flavonoids, increased TAC and POD activity, but decreased the ascorbate content in the leaves, and inhibited the accumulation of epidermal flavonoids in all basil varieties. Furthermore, characteristic leaf curling and UV-B-induced inhibition of plant growth were observed in all basil varieties, while a pro-oxidant effect of UV-B was indicated with H2O2 accumulation in the leaves and spotty leaf browning. The extent of these morphological changes, and oxidative damage depended on the basil cultivar, implies a genotype-specific tolerance mechanism to high doses of UV-B irradiation.

Chloroplast movement rapidly ameliorates the effects of suboptimal light intensity by accumulating along the periclinal cell walls, as well as the effects of excess light by shifting to the anticlinal cell walls. These acclimation responses are triggered by phototropins located at the plasma membrane and chloroplast envelope. Here, we used a recently developed non-invasive system sensitive to very small changes in red light leaf transmittance to perform long-term continuous measurements of dark–light transitions. As a model system, we used variegated Pelargonium zonale leaves containing green sectors (GS) with fully developed chloroplasts and achlorophyllous, white sectors (WS) with undifferentiated plastids, and higher phototropin expression levels. We observed biphasic changes in the red-light transmittance and oscillations triggered by medium intensities of white light, described by a transient peak preceded by a constant decrease in transmittance level. A slight change in red-light transmittance was recorded even in WS. Furthermore, the chloroplast position at lower light intensities affected the rapid light curves, while high light intensity decreased saturated electron transport, maximum quantum efficiency of photosystem II, and increased non-photochemical quenching of chlorophyll fluorescence and epidermal flavonoids. Our results extend the knowledge of light-dependent chloroplast movements and thus contribute to a better understanding of their role in regulating photosynthesis under fluctuating light conditions.

Due to increased urbanization and industrialization, the emission of toxic material into the atmosphere is in expansion, which has a negative impact on the environment and human health. In this research, we monitored the effect of air pollution on the peroxidase (POD) activity and total antioxidant capacity of different tree species during the growing season. The main goal was to determine which tree species developed the highest tolerance to unfavorable environmental conditions at the end of growing season, based on the response of their antioxidative metabolism. The greatest change in POD activity was observed in the Fagus sylvatica L. leaves, where enzyme activity was more than doubled in the autumn, in comparison to spring. On the other hand, decrease in POD activity was the greatest in Cedrus atlantica (Endl.) Manetti ex Carrière needles. Moreover, total antioxidative capacity was altered during growing season in almost all examined tree species. The Magnolia spp. showed the most consistent response to the given environmental pollution with both portrayed parameters induced during growing season. In general, we can conclude that the tree species investigated in this research possess distinctive tolerance potential to air pollutants.

Three basil plant varieties (Ocimum basilicum var. Genovese, Ocimum × citriodorum, and Ocimum basilicum var. purpurascens) were grown under moderate light (about 300 µmol photons m−2 s−1) in a glasshouse or growth chamber and then either transferred to an open field (average daily dose: 29.2 kJ m−2 d−1) or additionally exposed to UV-B irradiation in a growth chamber (29.16 kJ m−2 d−1), to reveal the variety-specific and light-specific acclimation responses. Total antioxidant capacity (TAC), phenolic profile, ascorbate content, and class III peroxidase (POD) activity were used to determine the antioxidant status of leaves under all four light regimes. Exposure to high solar irradiation at the open field resulted in an increase in TAC, total hydroxycinnamic acids (HCAs, especially caffeic acid), flavonoids, and epidermal UV-absorbing substances in all three varieties, as well as a two-fold increase in the leaf dry/fresh weight ratio. The supplemental UV-B irradiation induced preferential accumulation of HCAs (rosmarinic acid) over flavonoids, increased TAC and POD activity, but decreased the ascorbate content in the leaves, and inhibited the accumulation of epidermal flavonoids in all basil varieties. Furthermore, characteristic leaf curling and UV-B-induced inhibition of plant growth were observed in all basil varieties, while a pro-oxidant effect of UV-B was indicated with H2O2 accumulation in the leaves and spotty leaf browning. The extent of these morphological changes, and oxidative damage depended on the basil cultivar, implies a genotype-specific tolerance mechanism to high doses of UV-B irradiation.

Street trees are important component of urban forest presenting a first barrier between air pollution originated from vehicle traffic and pedestrians. It implies that an improvement of air quality in urban areas greatly depends on green biomass, in short, the bigger and greener tree crown, better for human health and wellbeing. Determination of Leaf Nitrogen Balance Index (LNBI) and chlorophyll concentration (ChlC) by a non-invasive methodology and a user friendly instrument (Dualex 4, Force), widely used in agronomy and horticulture, was tested here for the assessment of tree fitness in urban zones. Investment of energy and resources either in growth or defence according to the tradeoff strategy of plants may be indicated by LNBI, which approximately presents a Nitrogen/Carbon ratio. We selected few tree species from Belgrade’s streets to determine those two parameters during summer. We also presented the changes in those parameters of the introduced bamboo species within ten years at several urban locations in Belgrade differing in air pollution aiming to evaluate usefulness the LNBI parameter in access of multiyear exposure to the effect of intense vehicle traffic. Numerous limiting factors for development of healthy tree crowns in urban ecosystem, such as low capacity to cope with toxic pollutant, sensitivity to diseases, early senescence and etc., greatly depends on tree species. We propose this methodology may also contribute in the process of choice of the adequate tree species to be planted along streets.

Three varieties of basil (Ocimum x citriodorum, Ocimum basilicum var. Genovese and Ocimumbasilicum var. purpurascens) were used to examine the effect of different PAR intensities (100, 400and 1400 µmol photons m-2s-1), as well as different UV-B/PAR ratios, on leaf phenolics accumulation, and components of the ascorbate-glutathione cycle. Phenolic compounds represent themost abundant class of secondary metabolites, and their function in plants involves protectionagainst numerous abiotic stresses, role in growth and development, flowering, reproduction andseed dispersion. A preferential accumulation of HCAs over Flav, induction of class III POD activityand decreased ascorbate content were characteristic responses to pro-oxidative effect of the highUV-B/PAR ratio in all three basil varieties. The most remarkable result was the lack of accumulationof epidermal UV absorbing substances, which appeared to be a crucial photoprotective mechanism in sunlight. The contrasting effect of ecologically relevant UV-B radiation on basil plants,pro-oxidative vs. acclimative, was determined by the quality and intensity of the background light.Acclimation of basil to high light comprises a number of processes, among which are the accumulation of epidermal flavonoids and total leaf phenolics, antioxidant response (increase in Asc andGSH) and lack of downregulation of PSII upon increasing light intensity. Among varieties that weused as model system in this study, purple basil, with the highest constitutive amount of anthocyanidins, showed the least induction of epidermal flavonoids and lack of light effect upon transferfrom initial 50 to 250 µmol photons m-2s-1.

Ramonda serbica Panc. is a resurrection plant species that can survive desiccation for a longperiod and fully resume metabolic functions upon rewatering in a very short period, even within48 h. The goal of this study was to identify key candidates and pathways involved in desiccation tolerance in R. serbica. To achieve this, systems biology approach combining transcriptomics,proteomics, and analysis of specific metabolites was employed. In addition, FTIR analysis of thecell wall polymers and a detailed analysis of the photosynthetic electron transport (PET) chainwere performed. In total, 1192 different protein groups were quantified by TMT-based comparative quantitative proteomics. Among them, 408 protein groups showed a statistically significantdifference in abundance between hydrated (HL) and desiccated leaves (DL). Upon desiccation, themajority of proteins related to photosynthetic processes were less abundant, while chlorophyllfluorescence measurements implied shifting from linear photosynthetic transport (PET) to cyclicelectron transport (CET). The amounts of H2O2 scavenging enzymes, including ascorbate-glutathione cycle components, catalases, peroxiredoxins, Fe-, and Mn- superoxide dismutase (SOD) werereduced in DL. However, four Cu/ZnSOD isoforms, three polyphenol oxidases, six germin-like proteins (GLPs), and 22 late embryogenesis abundant proteins (LEAPs; mainly LEA4 and dehydrins),were desiccation-inducible. Desiccation-induced cell wall remodelling by changes in cell wallpolymer composition might be linked with pectin demethylesterification and GLP-derived H2O2/HO•. Our study demonstrated that desiccation tolerance in R. serbica is a complex, species-specific process orchestrated by several metabolic pathways and regulatory networks acting at the transcript, protein, metabolite and physiological levels.

Drought causes huge agricultural and economic losses worldwide. Silicon (Si) is considered a beneficial element for plants. It mitigates stress caused by salinity, drought, and high and low temperatures by promoting antioxidant production. However, the underlying mechanisms are still not elucidated. We investigated Si fertilisation effect on photosynthetic parameters, trichome number, leaf optical properties, as well as profiles of amino acids and polyphenols in barley exposed to water shortage. Silicon was applied in three growth stages: (i) before the flag leaf emergence; (ii) prior to the grain filling phase; (iii) at the grain filling phase start. Drought negatively impacts photochemical efficiency, stomatal conductance, photosynthetic pigment content, and leaf reflective and transmissive properties. Si application between flag leaf emergence and grain filling had the strongest effect on light reflectance. Among all analyzed phenolics, saponarin was the most abundant in all samples, irrespective of water regime and Si supply. Caffeoyl ester was the only hydroxycinnamic acid showing significant accumulation with the latest applied Si compared to no added Si upon drought. The major amino acids in barley leaves were glutamate, glutamine, aspartate, asparagine, and serine. Aspartate content was the highest in leaves exposed to drought without Si addition, while lysine was the most accumulated in the leaves supplemented by Si at the grain filling phase start. Proline was 2.5 times more abundant in the leaves exposed to drought regardless of Si treatment. Taken together, although Si did not mitigate drought stress effects, its effect was dependent on the barley growth phase prior to supplementation.

The resurrection plant Ramonda serbica Panc. survives long desiccation periods and fully recovers metabolic functions within one day upon watering. This study aimed to identify key candidates and pathways involved in desiccation tolerance in R. serbica. We combined differential transcriptomics and proteomics, phenolic and sugar analysis, FTIR analysis of the cell wall polymers, and detailed analysis of the photosynthetic electron transport (PET) chain. The proteomic analysis allowed the relative quantification of 1192 different protein groups, of which 408 were differentially abundant between hydrated (HL) and desiccated leaves (DL). Almost all differentially abundant proteins related to photosynthetic processes were less abundant, while chlorophyll fluorescence measurements implied shifting from linear PET to cyclic electron transport (CET). The levels of H2O2 scavenging enzymes, ascorbate-glutathione cycle components, catalases, peroxiredoxins, Fe-, and Mn superoxide dismutase (SOD) were reduced in DL. However, six germin-like proteins (GLPs), four Cu/ ZnSOD isoforms, three polyphenol oxidases, and 22 late embryogenesis abundant proteins (LEAPs; mainly LEA4 and dehydrins), were desiccation-inducible. Desiccation provoked cell wall remodeling related to GLP-derived H2O2/HO center dot activity and pectin demethylesterification. This comprehensive study contributes to understanding the role and regulation of the main metabolic pathways during desiccation aiming at crop drought tolerance improvement.

Uzimajući u obzir klimatske promjene koje podrazumijevaju smanjenje količine padavina i porast temperatura, suša je postala globalni problem za koji se smatra da će biti aktuelan još dugo vremena u budućnosti. Osim problema koje stvara u brojnim životnim sferama, suša je jedan od najozbiljnijih faktora koji negativno utiče na poljoprivredu, s obzirom da nedovoljno vodosnabdijevanje negativno utiče na rast i razvoj biljaka. U uslovima suše povećana produkcija reaktivnih vrsta kiseonika može da izazove pomjeranje ravnoteže u ćelijskim oksidoredukcionim reakcijama u smjeru oksidacije te da dovede do nastanka oksidativnog stresa. Posljedice oksidativnog stresa su strukturna i funkcionalna oštećenja ćelijskih komponenti koja dovode do poremećaja u metabolizmu i funkcionisanju ćelije.Veoma važnu ulogu u toleranciji biljaka na stres izazvan sušom ima antioksidativni sistem zaštite koji neizbježno uključuje enzime superoksid dismutazu, katalazu, peroksidaze Klase III i askorbat peroksidazu, ali takođe i niskomolekularne antioksidante poput askorbata, glutationa, fenola i karotenoida. Posljednjih godina se naglo povećao interes za korištenje ekološki opravdanih i neinvazivnih sredstava kojima se unaprijeđuje problem vodosnabdijevanja biljaka, a velika pažnja je posvećena primjeni prirodnih aluminosilikata, od kojih je najpoznatiji zeolit. Iako nisu mnogobrojni, postoje radovi koji upućuju da ovaj prirodni mineral može značajno da doprinese poboljšanju vodnog režima biljaka zbog osobine vezivanja te uravnoteženog otpuštanja vode. U ovoj doktorskoj disertaciji predmet istraživanja je uključio dvije biljne vrste različite po tipu fotosintetičkog metabolizma i adaptivnim strategijama na prilagođavanje na sušu, a to su paradajz (Solanum lycopersicum L.) i kukuruz (Zea mays L.). Fokus istraživanja bio je ispitivanje mogućnosti primjene zeolita u svrhu sprječavanja ili ublažavanja posljedica stresa izazvanog sušom kod biljaka paradajza i kukuruza, ali i ispitivanje mogućeg različit, Taking into account climate change, which implies a precipitation decreasing and temperatures rising, drought has become a global problem that is considered to be relevant for a long time to come. In addition to the problems it creates in many spheres of life, drought is one of the most serious factors that negatively affects agriculture, given that insufficient water supply disrupts the growth and development of plants. The production of reactive oxygen species in drought conditions can cause an inbalance of cellular redox homeostasis in the direction of oxidation and lead to the formation of oxidative stress. The consequences of oxidative stress are structural and functional damages of cellular compartments which leads to disturbance of metabolism and cell function. A very important role in plant tolerance to drought stress has the antioxidant protection systems that inevitably include theenzymes superoxide dismutase, catalase, Class III peroxidases and ascorbate peroxidase, but also low molecular weight antioxidants such as ascorbate, glutathione phenol and carotenoids. In recent years, there has been a sharp increase in interest in the use of environmentally sound and non- invasive means to improve the water supply of plants, and much attention has been paid to the use of natural aluminosilicates, the most famous of which is zeolite. Although not numerous, there are studies that suggest that this natural mineral can significantly contribute to the improvement of the water regime of plants due to the binding properties and balanced release of water. In this PhD thesis, the subject of research included two plant species different in type of photosynthetic metabolism and adaptive drought adaptation strategies, namely tomatoes (Solanum lycopersicum L.) and maize (Zea mays L.). The focus of research was to examine the possibility of using zeolite to prevent or mitigate the effects of drought stress in tomato and maize plants, but also to examine the possible diff

Two tomato genotypes with constitutively different ABA level, flacca mutant and wild type of Ailsa Craig cv. (WT), were subjected to three repeated drought cycles, with the aim to reveal the role of the abscisic acid (ABA) threshold in developing drought tolerance. Differential responses to drought of two genotypes were obtained: more pronounced stomatal closure, ABA biosynthesis and proline accumulation in WT compared to the mutant were compensated by dry weight accumulation accompanied by transient redox disbalance in flacca. Fourier-transform infrared (FTIR) spectra analysis of isolated cell wall material and morphological parameter measurements on tomato leaves indicated changes in dry weight accumulation and carbon re-allocation to cell wall constituents in flacca, but not in WT. A higher proportion of cellulose, pectin and lignin in isolated cell walls from flacca leaves further increased with repeated drought cycles. Different ABA-dependent stomatal closure between drought cycles implies that acquisition of stomatal sensitivity may be a part of stress memory mechanism developed under given conditions. The regulatory role of ABA in the cell wall restructuring and growth regulation under low leaf potential was discussed with emphasis on the beneficial effects of drought priming in developing differential defense strategies against drought.

The present study examined the effects of Candidatus Phytoplasma solani infection on antioxidative metabolism in leaves and roots of carrot (Daucus carota L.). Disease symptoms appeared at the end of June in the form of the chlorosis on some of the leaves, which became intensely red one week later, while the previously healthy leaves from the same branch becme chlorotic. A few days later, all leaves from the infected leaf branch were intensely red. Infected plants also had slower growth compared to the healthy ones with fewer leaf branches developed. The roots of infected plants were less developed, seared, or gummy with or without brown-colored root hair. The presence of the pathogen was detected by sequencing the 16S rRNA. National Center for Biotechnology Information (NCBI) BLAST analyses of the obtained sequence revealed 100% identity of tested strain with deposited Ca. Phytoplasma solani strains from various countries and hosts, all belonging to the "stolbur" group (16SrXII-A). Identity of 99.74% was found when the tested Serbian strain (MF503627) was compared with the reference stolbur strain STOL11 (AF248959). The oxidative damage of membranes in carrot cells was accompanied by a decrease in the content of photosynthetic pigments. Furthermore, for the determination of specific scavenging properties of the extracts, in vitro antioxidant assay was performed. In phytoplasma-infected carrot leaves, there was a greater reduction in the level of glutathione content (GSH); however; flavonoids and anthocyanidins seem to be responsible for the accompanied increased antioxidative capacity against hydroxyl radical and hydrogen peroxide.

Resurrection plant Ramonda serbica Panc. survives desiccation for a long period and fully recovers metabolic functions already within one day upon watering [1]. Besides osmotic stress, desiccation provokes the accelerated generation of reactive oxygen species. The aim of our study was obtaining more insight into the mechanisms of desiccation tolerance in R. serbica by TMT labelled comparative quantitative proteomics of hydrated (HL) and desiccated leaves (DL). After de novo transcriptome analysis, 189456 transcripts with 189003 unigenes were annotated with seven common databases. Proteomic analysis allowed for the relative quantification of 895 different protein groups, 321 with a statistically significant difference in abundance between FL and DL. Among them, 25% referred to chloroplast and almost the same percentage were associated with desiccation and oxidative stress. Almost all differentially abundant proteins related to photosynthetic processes were down-regulated in DL, while those required for protein translation were more abundant in HL. Within differentially abundant proteins involved in antioxidative defence, the levels of enzymes involved in ascorbate-glutathione cycle, peroxiredoxins, Fe and Mn superoxide dismutase (SOD) were all reduced in DL, while germin-like proteins, three Cu/Zn SOD isoforms and polyphenol oxidases were more abundant in DL compared with HL. The protein family with the highest number of members showing the greatest accumulation upon desiccation comprised twenty different late embryogenesis abundant proteins (LEAPs), similarly as found by differential transcriptomic analysis. Taken together, our results imply a key role of LEAPs and Cu/Zn SOD in protective mechanism against desiccation in R. serbica, that may have significant implications on drought-related studies of crops grown in arid areas. This work was supported by the Science Fund of the Republic of Serbia (PROMIS project LEAPSyn-SCI, grant number 6039663). M.V. wishes to ackn

Resurrection plant Ramonda serbica Panc. survives desiccation for a long period and fully recovers metabolic functions already within one day upon watering [1]. Besides osmotic stress, desiccation provokes the accelerated generation of reactive oxygen species. The aim of our study was obtaining more insight into the mechanisms of desiccation tolerance in R. serbica by TMT labelled comparative quantitative proteomics of hydrated (HL) and desiccated leaves (DL). After de novo transcriptome analysis, 189456 transcripts with 189003 unigenes were annotated with seven common databases. Proteomic analysis allowed for the relative quantification of 895 different protein groups, 321 with a statistically significant difference in abundance between FL and DL. Among them, 25% referred to chloroplast and almost the same percentage were associated with desiccation and oxidative stress. Almost all differentially abundant proteins related to photosynthetic processes were down-regulated in DL, while those required for protein translation were more abundant in HL. Within differentially abundant proteins involved in antioxidative defence, the levels of enzymes involved in ascorbate-glutathione cycle, peroxiredoxins, Fe and Mn superoxide dismutase (SOD) were all reduced in DL, while germin-like proteins, three Cu/Zn SOD isoforms and polyphenol oxidases were more abundant in DL compared with HL. The protein family with the highest number of members showing the greatest accumulation upon desiccation comprised twenty different late embryogenesis abundant proteins (LEAPs), similarly as found by differential transcriptomic analysis. Taken together, our results imply a key role of LEAPs and Cu/Zn SOD in protective mechanism against desiccation in R. serbica, that may have significant implications on drought-related studies of crops grown in arid areas. This work was supported by the Science Fund of the Republic of Serbia (PROMIS project LEAPSyn-SCI, grant number 6039663). M.V. wishes to ackn

Since 2011, the outbreaks of brown rot caused by Ralstonia solanacearum race 3, biovar 2, phylotype IIB-1 (R3/B2/PIIB-1) have significantly compromised potato production in Serbia. During 6 years of monitoring (2013-2018) among 3,524 potato tuber samples, 344 were found positive for brown rot disease. R. solanacearum R3/B2/PIIB-1 was isolated from seven cultivars among 12 monitored, and in five localities among 17 monitored. Cultivar Lady Claire was found to have the highest disease frequency (31.98%). A total of 78 isolates were identified by R. solanacearum-specific primer pairs (PS-1/PS-2 and OLI-1/Y-2), as well as the following tests: restriction fragment length polymorphism analysis, biovar determination, immunofluorescence, biochemical analysis, and pathogenicity. The genetic composition of 36 selected isolates assessed using multilocus sequence analysis with seven genes (adk, gapA, gdhA, gyrB, ppsA, hrpB, and fliC) showed that all isolates originating from Serbian potato were homogeneous. By using the TCS algorithm of concatenated sequences to get insight into the phylogeography of isolates and other R. solanacearum strains deposited in the NCBI database, we showed that their origin is undetermined. Peroxidase (POD) activity was measured in brown rotted potato tubers. A positive correlation was found between POD activity and disease severity rated on the analysed tubers. In general, POD activity increased by 2-22 times in vascular necrotic tissues compared to non-necrotic ones, and depended on disease severity but not on cultivar. Native polyacrylamide gel electrophoresis analysis of POD profiles resulted in a total of 10 distinct POD isoforms, of which PODs 3-5 were highly intensified in response to R. solanacearum.

Water deficit has a global impact on plant growth and crop yield. Climate changes are going to increase the intensity, duration and frequency of severe droughts, particularly in southern and south-eastern Europe, elevating the water scarcity issues. We aimed to assess the contribution of endogenous abscisic acid (ABA) in the protective mechanisms against water deficit, including stomatal conductance, relative water potential and the accumulation of osmoprotectants, as well as on growth parameters. To achieve that, we used a suitable model system, ABA-deficient tomato mutant, flacca and its parental line. Flacca mutant exhibited constitutively higher levels of soluble sugars (e.g., galactose, arabinose, sorbitol) and free amino acids (AAs) compared with the wild type (WT). Water deficit provoked the strong accumulation of proline in both genotypes, and total soluble sugars only in flacca. Upon re-watering, these osmolytes returned to the initial levels in both genotypes. Our results indicate that flacca compensated higher stomatal conductance with a higher constitutive level of free sugars and AAs. Additionally, we suggest that the accumulation of AAs, particularly proline and its precursors and specific branched-chain AAs in both, glucose and sucrose in flacca, and sorbitol in WT, could contribute to maintaining growth rate during water deficit and recovery in both tomato genotypes.

The present invention is in the field of aqueous emulsions that dry into water-insoluble or water-resistant structures that are useful for active packaging, manufactured devices and components, and other applications. The aqueous emulsions of the present invention comprise biopolymers, metal in the form of a salt, nanoparticles or metal oxide nanoparticles, essential oil, and additives such as surfactants and plasticizers. When the components of the emulsion are mixed following the distinctive method of preparation, a water-soluble fluid is obtained, which, upon drying, becomes a water-insoluble or water-resistant solid exhibiting antimicrobial, antioxidative, and other useful properties including tensile strength, elasticity, transparency. The obtained fluid may be applied by spraying, pouring, injecting, 3-D printing, or otherwise formed into a solid product of any geometrical shape including film, foil, or other 3-D shape.

Trehalose and its precursor, trehalose 6-phosphate (T6P), are essential regulators of plant response to abiotic and biotic stress. Here we used the specific host-insect interaction between Linaria vulgaris (Plantaginaceae) and stem-galling weevil, Rhinusa pilosa (Mecinini, Curculionidae) with the aim to distinguish carbohydrate allocation patterns in response to herbivory, gall formation (G1, 24 h after oviposition), and gall development (G2, 7 days after oviposition) under controlled conditions. The hypothesis is that herbivory and galling induce distinct responses in both leaves and stems, and that shifts in carbon allocations are regulated by signaling sugars. Systemic response to herbivory was accumulation of T6P and maltose. The main feature of G1 in the stems was accumulation of trehalose, accompanied by increased T6P, turanose and glucose content, oppositely to the leaves. In G2, galls had 3-folds higher weight than controls, with further accumulation of fructose, glucose, turanose, and total water-insoluble carbohydrates (TIC), while the sucrose/hexose ratio decreased. Analysis of fast chlorophyll fluorescence kinetic (OJIP) transients in G2 showed a slight decrease in quantum yield of electron transport flux from QA to QB, and towards photosystem I acceptor side, correlated with the decreased content of photosynthetic pigments and hexoses accumulation. Redistribution of photosynthates, and accumulation of T6P were induced in response to herbivory, indicating its signaling role. The results support the hypothesis that R. pilosa can induce plant reprogramming towards the accumulation of beneficial carbohydrates in developing gall by mechanisms which include both T6P and trehalose.

Bacterial leaf spot caused by the plant pathogenic bacterium Pseudomonas syringae pv. coriandricola (Psc) was observed on carrot, parsnip, and parsley grown on a vegetable farm in the Vojvodina Province of Serbia. Nonfluorescent bacterial colonies were isolated from diseased leaves and characterized using different molecular techniques. Repetitive element PCR fingerprinting with five oligonucleotide primers (BOX, ERIC, GTG5, REP, and SERE) and the randomly amplified polymorphic DNA-PCR with the M13 primer revealed identical fingerprint patterns for all tested strains. Multilocus sequence analysis of four housekeeping genes (gapA, gltA, gyrB, and rpoD) showed a high degree (99.8 to 100%) of homology with sequences of Psc strains deposited in the Plant-Associated Microbes Database and NCBI database. The tested strains caused bacterial leaf spot symptoms on all three host plants. Host-strain specificity was not found in cross-pathogenicity tests, but the plant response (peroxidase induction and chlorophyll bleaching) was more pronounced in carrot and parsley than in parsnip.