Sinensis Plants Research Articles

Pemanfaatan IoT (Internet of Things) Pada Irigasi Tetes Untuk Tanaman Jeruk

Tanaman jeruk manis merupakan salah satu produk unggulan Desa Petungsewu Kabupaten Malang. Selama ini, Mitra mengandalkan air hujan dengan menggunakan sistem tadah hujan untuk mengairi tanamannya. Persoalan muncul tatkala musim kemarau, terbatasnya air menjadi kendala utama saat Mitra ingin melakukan penyiraman maupun penyemprotan. Akibat terbatasnya air, tanaman hanya mampu berbuah sekali dalam setahun tidak seperti tanaman di perkebunan lain yang mendapatkan irigasi air sungai yang mampu berbuah dua kali dalam setahun. Untuk mengatasi terbatasnya air, maka diusulkan suatu tandon air dengan ukuran 4x6x2 m3 sebagai tempat penyimpanan air dari sistem tadah hujan, sedangkan untuk mengendalikan penggunaan air saat melakukan penyiraman digunakan sistem irigasi tetes yang dikendalikan menggunakan teknologi Internet of Things (IoT). Selain menyediakan tandon air, pada kegiatan ini juga dibangun suatu surau di atas tandon dan toilet. Karena ketidak tersediaan sumber energi listrik, maka kegiatan ini juga menyediakan sumber energi terbarukan berupa energi panel surya. Sistem penyiraman dilakukan secara otomatis menggunakan sensor kelembaban tanah, jika kelembaban kurang dari 70% maka valve akan membuka sehingga air mengalir, sebaliknya jika kelembaban telah terpenuhi maka valve akan menutup. Adanya kegiatan ini, Mitra dapat melakukan penyiraman tanaman secara otomatis meskipun di musim kemarau, dan tanaman jeruk bisa berbuah dua kali dalam setahun

Up-regulation of microRNA targets correlates with symptom severity in Citrus sinensis plants infected with two different isolates of citrus psorosis virus.

MAIN CONCLUSION: miRNA targets from Citrus sinensis are predicted and validated using degradome data. They show an up-regulation upon infection with CPsV, with a positive correlation between target expression and symptom severity. Sweet orange (Citrus sinensis) may suffer from disease symptoms induced by virus infections, thus resulting in drastic economic losses. Infection of sweet orange plants with two isolates of citrus psorosis virus (CPsV), expressing different symptomatologies, alters the accumulation of a set of endogenous microRNAs (miRNAs). Here, we predicted ten putative targets from four down-regulated miRNAs: three belonging to the CCAAT-binding transcription factor family (CBFAs); an Ethylene-responsive transcription factor (RAP2-7); an Integrase-type DNA-binding superfamily protein (AP2B); Transport inhibitor response 1 (TIR1); GRR1-like protein 1-related (GRR1); Argonaute 2-related (AGO2), Argonaute 7 (AGO7), and a long non-coding RNA (ncRNA). We validated six of them through analysis of leaf degradome data. Expressions of the validated targets increase in infected samples compared to healthy tissue, showing a more striking up-regulation those samples with higher symptom severity. This study contributes to the understanding of the miRNA-mediated regulation of important transcripts in Citrus sinensis through target validation and shed light in the manner a virus can alter host regulatory mechanisms leading to symptom expression.

Extraction of distribution information of Angelicae sinensis plants in Weiyuan county based on remote sensing technology

Due to the large amount of nutrients required during the cultivation of Angelica sinensis and in order to prevent the occurrence of pests and diseases,and the annual reduction of the planting area of Angelica and the balance of supply and demand of A. sinensis,the A. sinensis plantation adopts the rotation mode. This paper takes Wuyuan county of Gansu province as the research scope and use GF-1 Satellite data as the data source,using remote sensing technology combined with field survey results,to explore the effective method of visual interpretation for the extraction of A. sinensis planting area. A sample was selected to generate a spectrum according to different feature types. The different characteristics of A. sinensis and other features were analyzed and distinguished in remote sensing images,so that the A. sinensis planting plots were extracted and verified in remote sensing images. The results showed that the accuracy verification value of the visual interpretation method was 95. 85%. It is determined that the visual interpretation method can effectively extract the A. sinensis planting plots within the research scope and realize the comprehensive grasp of the spatial distribution information of A. sinensis.

Arbuscular Mycorrhizal Fungi Effectively Enhances the Growth of Gleditsia sinensis Lam. Seedlings under Greenhouse Conditions

The Chinese honey locust tree Gleditsia sinensis Lam. (Fabaceae) is a precious ecological and economic tree species that has wide-ranging usage. However, knowledge regarding seedling cultivation (especially the use of arbuscular mycorrhizal fungi (AMF)) is scarce, which limits the developent of Gleditsia plantations. A pot experiment was carried out under greenhouse conditions to estimate the effects of three AMF strains (Funneliformis mosseae 1, Funneliformis mosseae 2, and Diversispora tortuosa) on the growth, photosynthetic rate, and nutrient content of G. sinensis seedlings. Results showed that the growth parameters (seedling height, basal diameter, dry biomass) of the seedlings were significantly increased by each of the three AMF strains, associated with high root colonization rates (greater than 75%). Chlorophyll concentrations and photosynthetic rates were also increased by AMF, and phosphorus (P), and potassium (K) content in the three organs (leaf, stem, and root), and nitrogen (N) content in the leaf and stem of arbuscular mycorrhizal (AM) seedlings were significantly higher than in non-AM seedlings. Mycorrhizal dependency of the AM seedlings was greater than 350%, and significantly correlated with the increased P and K content in all three organs and increased N content in the leaf and stem. Positive effects of F. mosseae on growth and the nutrient content of seedlings were higher than those of D. tortuosa, but no significant different effects on G. sinensis seedlings were observed between the two strains of F. mosseae. Hence, growth of G. sinensis seedlings was effectively enhanced by AMF, with F. mosseae being more suitable for the inoculation of G. sinensis seedlings. These results indicate that arbuscular mycorrhization is beneficial for the growth of young G. sinensis plants. Further research is needed to determine whether the effects can be reproduced in a forest situation.

The effect of drought conditions on sweet orange (Citrus sinensis) plants infected with citrus tristeza virus (CTV)

Brazil is one of the world’s largest producers of citrus. However, production is challenged due to biotic and abiotic factors limiting crop health. The aim of this work was to evaluate the influence of water deficit in sweet orange (Citrus sinensis) cv. Pera Bianchi inoculated with citrus tristeza virus (CTV). Two isolates of CTV were used, one causing severe symptoms (Forte Rolândia) and the second causing mild symptoms (Pera IAC), grafted on Rangpur lime (Citrus limonia) and Swingle citrumelo [Citrus paradisi x Poncirus trifoliata], and the indicator sweet orange Pera Bianchi, free of virus, and healthy controls containing only the indicator budwood. The water regime for the plants was field capacity or 50% field capacity. After five months of controlled irrigation, biochemical variables were measured (protein, proline content and catalase activity), and real-time RT-PCR amplification of the virus was performed for detection and quantification of viral titer. Differences were observed in the total protein content and proline, with greater accumulation in plants maintained under water deficit. There was no effect of drought on the population of viral isolates, but the plants held at field capacity and inoculated with the severe isolate had a higher viral titer.

Arbuscular Mycorrhiza Improves Leaf Food Quality of Tea Plants

Tea (Camellia sinensis) plants inhabit arbuscular mycorrhizal fungi (AMF) in rhizosphere, whereas it is not clear whether AMF improves leaf food quality of tea plants. A potted study was conducted to determine effects of Claroideoglomus etunicatum, Diversispora spurca, D. versiformis and a mixture of the three AMF species on leaf sugar, amino acid, soluble protein, tea polyphenol, catechuic acid, and flavonoid contents of Camellia sinensis ‘Fuding Dabaicha’ seedlings. After 12 weeks of AMF inoculation, mycorrhizal plants recorded significantly higher shoot biomass and total leaf area, whilst the effect was ranked as C. etunicatum > D. spurca > mixed-AMF > D. versiformis in the decreasing order. AMF treatments significantly increased leaf total amino acid concentrations, accompanied with up-regulation of amino acid synthetic enzymes genes glutamine synthetase (CsGS), glutamate synthase (CsGOGAT) and glutamate dehydrogenase (CsGDH). Leaf glucose, sucrose, total soluble protein, tea polyphenol, catechuic acid, and flavonoid contents were significantly higher in AMF- than in non-AMF-inoculated plants. In addition, mycorrhizal inoculation notably up-regulated the expression level of leaf 3-hydroxy-3-methylglutaryl coenzyme gene (CsHMGR), ascorbate peroxidase gene (CsAPX), and tea caffeine synthase 1 gene (CsTCS1). These results implied that AMF inoculation had positive effects on leaf food quality partly by means of up-regulation of relevant gene expression in ‘Fuding Dabaicha’ seedlings.
 
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 In press - Online First. Article has been peer reviewed, accepted for publication and published online without pagination. It will receive pagination when the issue will be ready for publishing as a complete number (Volume 47, Issue 3, 2019). The article is searchable and citable by Digital Object Identifier (DOI). DOI link will become active after the article will be included in the complete issue.
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Identification of a Novel Gene Encoding the Specialized Alanine Decarboxylase in Tea (Camellia sinensis) Plants.

Theanine, a unique amino acid in Camellia sinensis, accounts for more than 50% of total free amino acids in tea and has a significant contribution to the quality of green tea. Previous research indicated that theanine is synthesized from glutamic acid (Glu) and ethylamine mainly in roots, and that theanine accumulation depends on the availability of ethylamine which is derived from alanine (Ala) decarboxylation catalyzed by alanine decarboxylase (AlaDC). However, the specific gene encoding AlaDC protein remains to be discovered in tea plants or in other species. To explore the gene of AlaDC in tea plants, the differences in theanine contents and gene expressions between pretreatment and posttreatment of long-time nitrogen starvation were analyzed in young roots of two tea cultivars. A novel gene annotated as serine decarboxylase (SDC) was noted for its expression levels, which showed high consistency with theanine content, and the expression was remarkably high in young roots under sufficient nitrogen condition. To verify its function, full-length complementary DNA (cDNA) of this candidate gene was cloned from young roots of tea seedlings, and the target protein was expressed and purified from Escherichia coli (E. coli). The enzymatic activity of the protein for Ala and Ser was measured in vitro using ultra-performance liquid chromatography coupled with mass spectrometry (UPLC-MS). The results illustrated that the target protein could catalyze the decarboxylation of Ala despite of its high similarity with SDC from other species. Therefore, this novel gene was identified as AlaDC and named CsAlaDC. Furthermore, the gene expression levels of CsAlaDC in different tissues of tea plants were also quantified with quantitative real-time PCR (qRT-PCR). The results suggest that transcription levels of CsAlaDC in root tissues are significantly higher than those in leaf tissues. That may explain why theanine biosynthesis preferentially occurs in the roots of tea plants. The expression of the gene was upregulated when nitrogen was present, suggesting that theanine biosynthesis is regulated by nitrogen supply and closely related to nitrogen metabolism for C. sinensis. The results of this study are significant supplements to the theanine biosynthetic pathway and provide evidence for the differential accumulation of theanine between C. sinensis and other species.

Characteristics of Free Amino Acids (the Quality Chemical Components of Tea) under Spatial Heterogeneity of Different Nitrogen Forms in Tea (Camellia sinensis) Plants.

Nitrogen (N) forms are closely related to tea quality, however, little is known about the characteristics of quality chemical components in tea under the spatial heterogeneity of different N forms. In this study, a split-root system, high performance liquid chromatography (HPLC), and root analysis system (WinRHIZO) were used to investigate free amino acids (FAAs) and root length of tea plants under the spatial heterogeneity of different N forms. Uniform. (U.) ammonium (NH4+) (both compartments had NH4+), U. nitrate (NO3−) (both compartments had NO3−), Split. (Sp.) NH4+ (one of the compartments had NH4+), and Sp. NO3− (the other compartment had NO3−) were performed. The ranking of total FAAs in leaves were as follows: U. NH4+ > Sp. NH4+/Sp. NO3− > U. NO3−. The FAA characteristics of Sp. NH4+/Sp. NO3− were more similar to those of U. NO3−. The contents of the important FAAs (aspartic acid, glutamic acid, and theanine) that determine the quality of tea, increased significantly in U. NH4+. The total root length in U. NH4+ was higher than that in the other treatments. More serious root browning was found in U. NO3−. In conclusion, NH4+ improved the accumulations of FAAs in tea leaves, which might be attributed to the root development.

Soil parameters drive the diversity of Citrus sinensis rhizosphere microbiota which exhibits a potential in plant drought stress alleviation

Plant associated microorganisms, particularly those exhibiting a plant growth promoting (PGP) effect, play an important role in plant nutrition and health and the adaptation to unfavorable climatic conditions, such as drought which threatens the productivity of agricultural crops. The selection of specific microbial populations in the soil habitats associated to plants depends upon the soil physico-chemical parameters besides the ‘rhizosphere effect’ played by each plant species through rhizodepositions. In this study, we investigated the community structure and PGP potential of the microbiota associated to Citrus sinensis plants located in different geographical regions of Tunisia. The bacteria community structure was correlated to soil physiochemical parameters and we identified potassium, carbon and organic matter content as drivers of the C. sinensis microbiota composition. The evaluation of the potential of selected bacteria as biofertilizer and bio-stimulator under drought stress was achieved through the phylogenetic and functional characterization of a large collection of bacterial strains isolated from the rhizosphere of C. sinensis. The strains were screened in vitro for putative plant growth promoting traits, and the six most promising isolates were tested in vivo on Solanum lycopersicum and Capsicum annuum model plants. The bacterized plants were cultivated under drought stress and compared with not bacterized and fully irrigated control plants. All the tested bacteria induced a significant increase in the number of leaves and in root biomass of both plant species compared to not inoculated plants. Our results highlighted that the strains Ensifer adhaerens S1B1.5 and Pseudomonas resinovorans S4R2.6 were, in particular, effective in promoting plant growth under water shortage, indicating them as promising strains for the development of sustainable biofertilizers suited for agriculture in arid and semi-arid regions characterized by water scarcity.

ITRAQ-Based Quantitative Proteomics Analysis Reveals the Mechanism Underlying the Weakening of Carbon Metabolism in Chlorotic Tea Leaves.

To uncover mechanism of highly weakened carbon metabolism in chlorotic tea (Camellia sinensis) plants, iTRAQ (isobaric tags for relative and absolute quantification)-based proteomic analyses were employed to study the differences in protein expression profiles in chlorophyll-deficient and normal green leaves in the tea plant cultivar “Huangjinya”. A total of 2110 proteins were identified in “Huangjinya”, and 173 proteins showed differential accumulations between the chlorotic and normal green leaves. Of these, 19 proteins were correlated with RNA expression levels, based on integrated analyses of the transcriptome and proteome. Moreover, the results of our analysis of differentially expressed proteins suggested that primary carbon metabolism (i.e., carbohydrate synthesis and transport) was inhibited in chlorotic tea leaves. The differentially expressed genes and proteins combined with photosynthetic phenotypic data indicated that 4-coumarate-CoA ligase (4CL) showed a major effect on repressing flavonoid metabolism, and abnormal developmental chloroplast inhibited the accumulation of chlorophyll and flavonoids because few carbon skeletons were provided as a result of a weakened primary carbon metabolism. Additionally, a positive feedback mechanism was verified at the protein level (Mg chelatase and chlorophyll b reductase) in the chlorophyll biosynthetic pathway, which might effectively promote the accumulation of chlorophyll b in response to the demand for this pigment in the cells of chlorotic tea leaves in weakened carbon metabolism.

Volatiles from Aquilaria sinensis damaged by Heortia vitessoides larvae deter the conspecific gravid adults and attract its predator Cantheconidea concinna

The effects of induced plant responses on herbivores are categorised as direct, by reducing herbivore development, or indirect, by affecting the performance of natural enemies. Here, we investigated a tritrophic system, which included the herbivore Heortia vitessoides, its host plant Aquilaria sinensis, and its predator Cantheconidea concinna. Herbivore-damaged A. sinensis plants released significantly greater amounts of volatiles than undamaged and mechanically damaged plants, with an obvious temporal trend. One day after initial herbivore damage, A. sinensis plants released large amounts of volatile compounds. Volatile compounds release gradually decreased over the next 3 d. The composition and relative concentrations of the electroantennographic detection (EAD)-active compounds, emitted after herbivore damage, varied significantly over the 4-d measurement period. In wind tunnel bioassays, mated H. vitessoides females showed a preference for undamaged plants over herbivore and mechanically damaged A. sinensis plants. In Y-tube bioassays, C. concinna preferred odours from herbivore-damaged plants to those from undamaged plants, especially after the early stages of insect attack. Our results indicate that the herbivore-induced compounds produced in response to attack by H. vitessoides larvae on A. sinensis plants could be used by both the herbivores themselves and their natural enemies to locate suitable host plants and prey, respectively.

Biotechnological potential of plant growth-promoting bacteria from the roots and rhizospheres of endemic plants in ironstone vegetation in southeastern Brazil

Microorganisms associated with plants have a great biotechnological potential, but investigations of these microorganisms associated with native plants in peculiar environments has been incipient. The objective of this study was to analyze the plant growth-promoting bacteria potential of cultivable bacteria associated with rare plants from the ferruginous rocky fields of the Brazilian Iron Quadrangle. The roots and rhizospheres of nine endemic plants species and samples of a root found in a lateritiric duricrust (canga) cave were collected, the culturable bacteria isolated and prospected for distinct biotechnological and ecological potentials. Out of the 148 isolates obtained, 8 (5.4%) showed potential to promote plant growth, whereas 4 (2.7%) isolates acted as biocontrol agents against Xanthomonas citri pathotype A (Xac306), reducing the cancrotic lesions by more than 60% when co-inoculated with this phytopathogen in Citrus sinensis plants. Moreover, other 4 (2.7%) isolates were classified as potential bioremediation agents, being able to withstand high concentrations of arsenite (5mM As3+) and arsenate (800mM As5+), by removing up to 35% and 15% of this metalloid in solution, respectively. These same four isolates had a positive influence on the growth of both the roots and the aerial parts when inoculated with tomato seeds in the soil contaminated with arsenic. This is the first time that an investigation highlights the potentialities of bacteria associated with rare plants of ferruginous rocky fields as a reservoir of microbiota of biotechnological and ecological interest, highlighting the importance of conservation of this area that is undergoing intense anthropic activity.

Transcriptome analysis using RNA-Seq revealed the effects of nitrogen form on major secondary metabolite biosynthesis in tea (Camellia sinensis) plants

The effects of the different forms of N, ammonium (NH4+) and nitrate (NO3−), on secondary metabolite biosynthesis in tea plants are well known. However, the mechanisms of underlying these effects are not well understood. This study generated transcriptomic profiles of Camellia sinensis treated with different N forms for 5 min and 96 h using RNA-Seq. Analysis of differentially expressed genes (DEGs) showed that the regulated DEGs involved in the secondary pathways in the NH4+-treatment were more abundant than those in the NO3−- and NH4++NO3−-treatments, demonstrating the preference of tea plants for NH4+ at the gene level. Expression analysis at different treatment times showed that increasing treatment time changed not only the number of DEGs involved in secondary metabolism but also the pathways of secondary biosynthesis. In addition, only a few DEGs involved in secondary metabolism were regulated in more than one treatment. These results suggested that the secondary biosynthesis pathways regulated by N were dependent on the N form and treatment time. The analysis of DEGs related to transport and N metabolism further confirmed this conclusion. Moreover, the change of DEGs in NO3−-treated tea plants suggested increase of treatment time might attenuate the flavonoid biosynthesis and enhance the theanine and caffeine biosynthesis. The identification of differentially expressed transcription factors revealed the possible crosstalk between the secondary metabolic pathways in C. sinensis. These results help facilitate an understanding of the effects of N on tea quality and represent a valuable reference for the rational application of N fertiliser on tea plantations.

Occurrence of Functional Molecules in the Flowers of Tea (Camellia sinensis) Plants: Evidence for a Second Resource.

Tea (Camellia sinensis) is an important crop, and its leaves are used to make the most widely consumed beverage, aside from water. People have been using leaves from tea plants to make teas for a long time. However, less attention has been paid to the flowers of tea plants, which is a waste of an abundant resource. In the past 15 years, researchers have attempted to discover, identify, and evaluate functional molecules from tea flowers, and have made insightful and useful discoveries. Here, we summarize the recent investigations into these functional molecules in tea flowers, including functional molecules similar to those in tea leaves, as well as the preponderant functional molecules in tea flowers. Tea flowers contain representative metabolites similar to those of tea leaves, such as catechins, flavonols, caffeine, and amino acids. The preponderant functional molecules in tea flowers include saponins, polysaccharides, aromatic compounds, spermidine derivatives, and functional proteins. We also review the safety and biological functions of tea flowers. Tea flower extracts are proposed to be of no toxicological concern based on evidence from the evaluation of mutagenicity, and acute and subchronic toxicity in rats. The presence of many functional metabolites in tea flowers indicates that tea flowers possess diverse biological functions, which are mostly related to catechins, polysaccharides, and saponins. Finally, we discuss the potential for, and challenges facing, future applications of tea flowers as a second resource from tea plants.

Efikasi Ekstrak Daun Pepaya Terhadap Nezara viridula L. (Hemiptera : Pentatomidae) Pada Polong Kacang Panjang

Nezara viridula is one of the major pests which attack bean (Vigna sinensis) plants. Crop damage due to attack of N. viridula depend on the number of pests, the availability of nutrition as well as biotic and abiotic factors. The useof synthetic insecticides continuously with inappropriate dose and time application cause negative impact on the environment, therefore the use of insecticide plant is one alternative to reduce pesticide dose. The purpose of this study was to determine the concentration of papaya leaf extract and verify application method which promote mortality of N. viridula ninfa. Experiment was set up in completely randomized block design with four treatments, i.e 40 g/100 mL of water, 50 g/100 mL of water, 60 g/100 mL of water and 70 g/100 mL of water. Observations were made on early symptoms of toxocity, the percentage of mortality, mortality rate and advanced stages of N. viridula. The results showed that application of papaya leaf extract with at 70 g / 100 mL of water through feed or contact caused 100% mortality of N. Viridula, with mortality rate of 4.75 days and 5.50 days. It is sugeested that vegetable-based insecticide could be used to decrease N. viridula attack on string bean pod.

Adulteration detection of tea samples based on plant rbcL gene sequencing

Tea is one of the most popular drinks in the world, but counterfeit or adulterated tea can be found now and then on the tea market. The traditional methods dependent on sensory, physical and chemical tests cannot identify the composition of adulterated plant species accurately. We developed therefore a method for identification of adulterated plants in tea based on qualitative detection of plant rbcL (Ribulose 1,5-bisphosphate carboxylase-oxygenase large subunit) fragments, which involved amplification, sequencing and sequence analyses of rbcL fragments. Seven tea samples were analyzed with the established method. The results showed that Yueyanghuangcha (yellow tea) and Xinyangmaojian (green tea) were pure with only detection of the tea plant Camellia sinensis; Zhengshan Souzhong (black tea), Tieguanyin (oolong tea), Tailaoyinzhen (white tea), Liupao and Pu-erh (dark tea) were, to a certain extent, adulterated with non-Camellia sinensis plants. The method introduced in this study only requires a small amount of tea samples, easy to operate and reliable. It can be used to determine if any tea samples are adulterated.

Effect of an Epichloë endophyte on adaptability to water stress in Festuca sinensis

Abstract As water stress, including drought and waterlogging, can severely affect plant growth, this study investigated the effects of an endophyte from the genus Epichloe on two different ecotypes of Festuca sinensis grass under five soil water conditions in a controlled greenhouse experiment. Changes in F. sinensis plants grown with (E+) and without the endophyte (E−) were evaluated as they were subjected to different water treatments (20%, 35%, 50%, 65% and 80% relative saturation moisture content, RSMC). Growth parameters such as plant height, number of tillers, blade width, stem diameter, root length, total biomass, root-shoot ratio and relative water content were determined. The results showed that drought and waterlogging significantly ( P F. sinensis . The presence of the endophyte significantly ( P

Photodynamic inactivation of conidia of the fungus Colletotrichum abscissum on Citrus sinensis plants with methylene blue under solar radiation

Antimicrobial photodynamic treatment (APDT) is a promising light based approach to control diseases caused by plant-pathogenic fungi. In the present study, we evaluated the effects of APDT with the phenothiazinium photosensitizer methylene blue (MB) under solar radiation on the germination and viability of conidia of the pathogenic fungus Colletotricum abscissum (former Colletotrichum acutatum sensu lato). Experiments were performed both on petals and leaves of sweet orange (Citrus sinensis) in different seasons and weather conditions. Conidial suspensions were deposited on the leaves and petals surface, treated with the PS (25 or 50μM) and exposed to solar radiation for only 30min. The effects of APDT on conidia were evaluated by counting the colony forming units recovered from leaves and petals and by direct evaluating conidial germination on the surface of these plant organs after the treatment. To better understand the mechanistic of conidial photodynamic inactivation, the effect of APDT on the permeability of the conidial plasma membrane was assessed using the fluorescent probe propidium iodide (PI) together with flow cytometry and fluorescence microscopy. APDT with MB and solar exposure killed C. abscissum conidia and prevented their germination on both leaves and petals of citrus. Reduction of conidial viability was up to three orders of magnitude and a complete photodynamic inactivation was achieved in some of the treatments. APDT damaged the conidial plasma membrane and increased its permeability to PI. No damage to sweet orange flowers or leaves was observed after APDT. The demonstration of the efficacy of APDT on the plant host represents a further step towards the use of the method for control phytopathogens in the field.

α-Farnesene and ocimene induce metabolite changes by volatile signaling in neighboring tea (Camellia sinensis) plants

Herbivore-induced plant volatiles (HIPVs) act as direct defenses against herbivores and as indirect defenses by attracting herbivore enemies. However, the involvement of HIPVs in within-plant or plant-to-plant signaling is not fully clarified. Furthermore, in contrast to model plants, HIPV signaling roles in crops have hardly been reported. Here, we investigated HIPVs emitted from tea (Camellia sinensis) plants, an important crop used for beverages, and their involvement in tea plant-to-plant signaling. To ensure uniform and sufficient exposure to HIPVs, jasmonic acid combined with mechanical damage (JAMD) was used to simulate herbivore attacks. Metabonomics techniques based on ultra-performance liquid chromatography/quadrupole time-of-flight mass spectrometry and gas chromatography-mass spectrometry were employed to determine metabolite changes in undamaged tea plants exposed to JAMD-stimulated volatiles. JAMD-stimulated volatiles mainly enhanced the amounts of 1-O-galloyl-6-O-luteoyl-α-d-glucose, assamicain C, 2,3,4,5-tetrahydroxy-6-oxohexyl gallate, quercetagitrin, 2-(2-(3,4-dihydroxyphenyl)-5,7-dihydroxy-4-oxo-4H-chromen-8-yl)-4,5-dihydroxy-6-(hydroxymethyl)-tetrahydro-2H-pyran-3-yl, 3,4-dimethoxybenzoate, 1,3,4,5,6,7-hexahydroxyheptan-2-one, and methyl gallate in neighboring undamaged tea leaves. Furthermore, α-farnesene and β-ocimene, which were produced after JAMD treatments, were identified as two main JAMD-stimulated volatiles altering metabolite profiles of the neighboring undamaged tea leaves. This research advances our understanding of the ecological functions of HIPVs and can be used to develop crop biological control agents against pest insects in the future.

Studies on the Biochemical Formation Pathway of the Amino Acid l-Theanine in Tea (Camellia sinensis) and Other Plants

Tea (Camellia sinensis) is the most widely consumed beverage aside from water. The flavor of tea is conferred by certain metabolites, especially l-theanine, in C. sinensis. To determine why more l-theanine accumulates in C. sinensis than in other plants, we compare l-theanine contents between C. sinensis and other plant species (Camellia nitidissima, Camellia japonica, Zea mays, Arabidopsis thaliana, and Solanum lycopersicum) and use a stable isotope labeling approach to elucidate its biosynthetic route. We quantify relevant intermediates and metabolites by mass spectrometry. l-Glutamic acid, a precursor of l-theanine, is present in most plants, while ethylamine, another precursor of l-theanine, specifically accumulates in Camellia species, especially C. sinensis. Most plants contain the enzyme/gene catalyzing the conversion of ethylamine and l-glutamic acid to l-theanine. After supplementation with [2H5]ethylamine, all the plants produce [2H5]l-theanine, which suggests that ethylamine availability is the reason for the difference in l-theanine accumulation between C. sinensis and other plants.