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Kasson M.T.,Pennsylvania State University | O'Donnell K.,National United University | Rooney A.P.,National United University | Sink S.,National United University | And 21 more authors.
Fungal Genetics and Biology | Year: 2013

Ambrosia beetle fungiculture represents one of the most ecologically and evolutionarily successful symbioses, as evidenced by the 11 independent origins and 3500 species of ambrosia beetles. Here we document the evolution of a clade within Fusarium associated with ambrosia beetles in the genus Euwallacea (Coleoptera: Scolytinae). Ambrosia Fusarium Clade (AFC) symbionts are unusual in that some are plant pathogens that cause significant damage in naïve natural and cultivated ecosystems, and currently threaten avocado production in the United States, Israel and Australia. Most AFC fusaria produce unusual clavate macroconidia that serve as a putative food source for their insect mutualists. AFC symbionts were abundant in the heads of four Euwallacea spp., which suggests that they are transported within and from the natal gallery in mandibular mycangia. In a four-locus phylogenetic analysis, the AFC was resolved in a strongly supported monophyletic group within the previously described Clade 3 of the Fusarium solani species complex (FSSC). Divergence-time estimates place the origin of the AFC in the early Miocene ~21.2. Mya, which coincides with the hypothesized adaptive radiation of the Xyleborini. Two strongly supported clades within the AFC (Clades A and B) were identified that include nine species lineages associated with ambrosia beetles, eight with Euwallacea spp. and one reportedly with Xyleborus ferrugineus, and two lineages with no known beetle association. More derived lineages within the AFC showed fixation of the clavate (club-shaped) macroconidial trait, while basal lineages showed a mix of clavate and more typical fusiform macroconidia. AFC lineages consisted mostly of genetically identical individuals associated with specific insect hosts in defined geographic locations, with at least three interspecific hybridization events inferred based on discordant placement in individual gene genealogies and detection of recombinant loci. Overall, these data are consistent with a strong evolutionary trend toward obligate symbiosis coupled with secondary contact and interspecific hybridization. © 2013 Elsevier Inc.

Pang Y.,Tea Research Institute of Sri Lanka | Abeysinghe I.S.B.,Tea Research Institute of Sri Lanka | He J.,Samuel Roberts Noble Foundation | He X.,Samuel Roberts Noble Foundation | And 5 more authors.
Plant Physiology | Year: 2013

Tea (Camellia sinensis) is rich in specialized metabolites, especially polyphenolic proanthocyanidins (PAs) and their precursors. To better understand the PA pathway in tea, we generated a complementary DNA library from leaf tissue of the blister blightresistant tea cultivar TRI2043 and functionally characterized key enzymes responsible for the biosynthesis of PA precursors. Structural genes encoding enzymes involved in the general phenylpropanoid/flavonoid pathway and the PA-specific branch pathway were well represented in the library. Recombinant tea leucoanthocyanidin reductase (CsLAR) expressed in Escherichia coli was active with leucocyanidin as substrate to produce the 2R,3S-trans-flavan-ol (+)-catechin in vitro. Two genes encoding anthocyanidin reductase, CsANR1 and CsANR2, were also expressed in E. coli, and the recombinant proteins exhibited similar kinetic properties. Both converted cyanidin to a mixture of (+)-epicatechin and (-)-catechin, although in different proportions, indicating that both enzymes possess epimerase activity. These epimers were unexpected based on the belief that tea PAs are made from (2)-epicatechin and (+)-catechin. Ectopic expression of CsANR2 or CsLAR led to the accumulation of low levels of PA precursors and their conjugates in Medicago truncatula hairy roots and anthocyanin-overproducing tobacco (Nicotiana tabacum), but levels of oligomeric PAs were very low. Surprisingly, the expression of CsLAR in tobacco overproducing anthocyanin led to the accumulation of higher levels of epicatechin and its glucoside than of catechin, again highlighting the potential importance of epimerization in flavan-3-ol biosynthesis. These data provide a resource for understanding tea PA biosynthesis and tools for the bioengineering of flavanols. © 2013 American Society of Plant Biologists. All Rights Reserved.

Jeganathan B.,University of Peradeniya | Punyasiri P.A.N.,University of Colombo | Kottawa-Arachchi J.D.,Tea Research Institute of Sri Lanka | Ranatunga M.A.B.,Tea Research Institute of Sri Lanka | And 3 more authors.
International Journal of Food Science | Year: 2016

Flavonol glycosides in tea leaves have been quantified as aglycones, quercetin, myricetin, and kaempferol. Occurrence of the said compounds was reported in fruits and vegetable for a long time in association with the antioxidant potential. However, data on flavonols in tea were scanty and, hence, this study aims to envisage the flavonol content in a representative pool of accessions present in the Sri Lankan tea germplasm. Significant amounts of myricetin, quercetin, and kaempferol have been detected in the beverage type tea accessions of the Sri Lankan tea germplasm. This study also revealed that tea is a good source of flavonol glycosides. The Camellia sinensis var. sinensis showed higher content of myricetin, quercetin, and total flavonols than var. assamica and ssp. lasiocalyx. Therefore flavonols and their glycosides can potentially be used in chemotaxonomic studies of tea germplasm. The nonbeverage type cultivars, especially Camellia rosaflora and Camellia japonica Red along with the exotic accessions resembling China type, could be useful in future germplasm studies because they are rich sources of flavonols, namely, quercetin and kaempferol, which are potent antioxidants. The flavonol profiles can be effectively used in choosing parents in tea breeding programmes to generate progenies with a wide range of flavonol glycosides. © 2016 Brasathe Jeganathan et al.

Perera G.A.A.R.,Tea Research Institute of Sri Lanka | Amarakoon A.M.T.,Tea Research Institute of Sri Lanka | Amarakoon A.M.T.,University of Kelaniya | Illeperuma D.C.K.,University of Peradeniya | Muthukumarana P.K.P.,Tea Research Institute of Sri Lanka
LWT - Food Science and Technology | Year: 2015

Effects of dhool (particles resulting from rolling of green leaf) fermented for varying durations, black tea and the rejected fraction in black tea manufacture which is known as 'broken mixed fannings' (BMF) as raw materials on the physicochemical and organoleptic properties of instant black tea were studied. Total polyphenols and theaflavins contents of instant black teas prepared by using fermented dhools (38.4-40.1 g/100g and 1.05-3.10 g/100 g respectively) were significantly higher than those of instant black teas prepared by using black tea (35.2g/100g and 0.37g/100g) and BMF (33.5 g/100 g and 0.28 g/100 g). Further, trolox equivalent (TE) antioxidant activities of instant black teas prepared by using fermented dhools (542 - 564 TE mg/g) were significantly higher than those of instant black teas prepared by using black tea (488 TE mg/g) and BMF (341 TE mg/g). Type of raw material did not affect significantly on the yield and fluoride and aluminium contents of instant black tea. Chemical composition, organoleptic properties, antioxidant activity and physical properties of instant black tea can be improved by using dhool fermented to 2-21/2h as raw material. © 2015 Elsevier Ltd.

PubMed | Tea Research Institute of Sri Lanka, University of Colombo, Coordinating Secretariat for Science and University of Peradeniya
Type: | Journal: Journal of analytical methods in chemistry | Year: 2015

Chemical analysis of the Sri Lankan tea (Camellia sinensis, L.) germplasm would immensely contribute to the success of the tea breeding programme. However, the polyphenols, particularly catechins (flavan-3-ols), are readily prone to oxidation in the conventional method of sample preparation. Therefore, optimization of the present sample preparation methodology for the profiling of metabolites is much important. Two sample preparation methodologies were compared, fresh leaves (as in the conventional procedures) and freeze-dried leaves (a new procedure), for quantification of major metabolites by employing two cultivars, one is known to be high quality black tea and the other low quality black tea. The amounts of major metabolites such as catechins, caffeine, gallic acid, and theobromine, recorded in the new sampling procedure via freeze-dried leaves, were significantly higher than those recorded in the conventional sample preparation procedure. Additionally new method required less amount of leaf sample for analysis of major metabolites and facilitates storage of samples until analysis. The freeze-dried method would be useful for high throughput analysis of large number of samples in shorter period without chemical deterioration starting from the point of harvest until usage. Hence, this method is more suitable for metabolite profiling of tea as well as other phenol rich plants.

Karlsson M.F.,Swedish University of Agricultural Sciences | Birgersson G.,Swedish University of Agricultural Sciences | Witzgall P.,Swedish University of Agricultural Sciences | Lekfeldt J.D.S.,University of Aarhus | And 4 more authors.
Phytochemistry | Year: 2013

Guatemalan potato moth, Tecia solanivora, lay eggs in the soil nearby potato Solanum spp. and larvae feed on the tubers. We investigated the oviposition behaviour of T. solanivora females and the survival of larval offspring on healthy vs. stressed, i.e. light exposed and/or damaged potato tubers. In choice tests, females laid significantly more eggs in response to potato odour of healthy tubers and female oviposition preference correlated with higher larval survival. Survival of larvae was negatively correlated with the tuber content of the steroid glycoalkaloids α-solanine and α-chaconine: healthy potatoes contained lower amounts than stressed tubers, ranging from 25 to 500 μg g-1 and from 30 to 600 μg g-1, respectively. Analysis of volatile compounds emitted by potato tubers revealed that stressed tubers could clearly be distinguished from healthy tubers by the composition of their volatile profiles. Compounds that contributed to this difference were e.g. decanal, nonanal, isopropyl myristate, phenylacetaldehyde, benzothiazole, heptadecane, octadecane, myristicin, E,E-α-farnesene and verbenone. Oviposition assays, when female moths were not in contact with the tubers, clearly demonstrated that volatiles guide the females to lay fewer eggs on stressed tubers that are of inferior quality for the larvae. We propose that volatiles, such as sesquiterpenes and aldehydes, mediate oviposition behaviour and are correlated with biosynthetically related, non-volatile compounds, such as steroidal glycoalkaloids, which influence larval survival. We conclude that the oviposition response and larval survival of T. solanivora on healthy vs. stressed tubers supports the preference performance hypothesis for insect herbivores. © 2012 Elsevier Ltd. All rights reserved.

Seneviratne G.,Sri Lanka Institute of Fundamental Studies | Jayasekara A.P.D.A.,Tea Research Institute of Sri Lanka | De Silva M.S.D.L.,Tea Research Institute of Sri Lanka | Abeysekera U.P.,Tea Research Institute of Sri Lanka
Soil Biology and Biochemistry | Year: 2011

Nitrogen fixing bacteria play a key role in the growth and persistence of effective microbial communities in the soil by supplying N through biological nitrogen fixation (BNF). In the long run, chemical inputs, particularly N fertilisers are known to adversely affect N2 fixers and hence maintenance of soil fertility and crop productivity. This study examined the effect of developed microbial biofilms with N2 fixers on restoration of soils deteriorated by conventional agricultural practices in tea cultivation. Just reducing recommended chemical fertiliser use by 50% significantly increased soil microbial biomass and BNF, and decreased soil NO3 - and pest infestation. The lower chemical fertiliser addition coupled with the biofilm-based biofertilisers known as biofilmed biofertilisers (BFBFs) further increased BNF significantly. The combined application significantly increased soil organic C by ca. 20%, and reduced leaf transpiration by ca. 40%. It also supported plant growth, rhizoremediation and soil moisture conservation in comparison to the 100% chemical fertilisation. Those improved performances were observed to be proportional to the increased density of soil bacteria, and have several agronomic and environmental implications. It is apparent from this study that replenishing the depleted soil microbial communities by applying such biofertilisers is likely to be beneficial in agroecosystems with chemical N fertiliser use, if they are to be sustained for crop production. © 2011 Elsevier Ltd.

Sinniah G.D.,Tea Research Institute of Sri Lanka | Wasantha Kumara K.L.,Ruhuna University | Karunajeewa D.G.N.P.,Tea Research Institute of Sri Lanka | Ranatunga M.A.B.,Tea Research Institute of Sri Lanka
Crop Protection | Year: 2016

Blister blight caused by the biotrophic fungus, Exobasidium vexans Massee, is the most problematic foliar disease of tea in Sri Lanka. A reliable and accurate method is needed for field assessment of severity of the disease for epidemiological studies, formulating disease control strategies and crop improvement programmes. A field assessment key with 0-6 scores was developed for blister blight, considering the lowest (0) and highest (>30%) limits of disease severity observed in the field and different stages of symptom development. The key was validated by six raters, 3 experienced and 3 inexperienced. The field assessment trials made using the key were accurate and precise (R2 > 0.80). The area under the disease progress curve (AUDPC), calculated using the disease severity levels obtained using the assessment key, was used to combine multiple observations of disease progress into a 0-9 susceptible scale. Ascending numbers in the scale represent increasing susceptibility. The new scale was proposed to discriminate blister blight resistance in tea accessions/cultivars in field screening. Screening trials for validation of the susceptible scale, conducted using tea cultivars of known resistance or susceptibility levels and newly developed accessions of tea, at three locations, revealed that the 0-9 scale is simple to apply, offers a fine discrimination of blister blight resistance levels, and allows objective evaluation. © 2015 Elsevier Ltd.

Freeman S.,Israel Agricultural Research Organization | Protasov A.,Israel Agricultural Research Organization | Sharon M.,Israel Agricultural Research Organization | Mohotti K.,Tea Research Institute of Sri Lanka | And 4 more authors.
Symbiosis | Year: 2012

The ambrosia beetle, Euwallacea aff. fornicata Eichhoff was first recorded in Israel in 2009. The symbiotic fungus Fusarium sp. nov., carried in the mandibular mycangia of the beetle, is responsible for typical wilt and dieback symptoms inflicted on avocado (Persea americana Miller) trees. The beetle-fungus complex has become a serious threat to the future of the avocado industry in Israel and elsewhere. When reared on Petri dishes, inoculated with 7-day-old cultures of the symbiotic Fusarium sp. nov., the beetle successfully completed its lifecycle and developed from egg to fertile adults in approximately 60 days. Galleries that were produced in the PDA medium by the adults, resembled those excavated in host plant xylem under natural host colonization conditions. Euwallacea aff. fornicata from avocado in Israel was not able to survive when fed with F. ambrosium but resulted in approximately 25 % mortality when fed on F. solani; both isolates originated from infected tea. Likewise, the larvae of E. fornicatus from tea in Sri Lanka, were not able to survive or complete their lifecycle when supplied with a feed of the Fusarium sp. nov. isolated from avocado in Israel. Isolates of two other Fusaria, F. mangiferae from mango and F. oxysporum f. sp. melonis from melon, were not able to support development or survival of the beetle larvae from avocado from Israel, using the same Petri dish rearing method. This indicates that the Fusarium sp. nov. isolate from avocado is obligately required for the survival and development of Euwallacea aff. fornicata currently occurring in Israel, affecting this crop and additional hosts. The usefulness of the Petri dish assay to study the interactions between ambrosia beetles and their fungal symbionts is discussed. © 2013 Springer Science+Business Media Dordrecht.

Ariyarathna H.A.C.K.,Tea Research Institute of Sri Lanka | Gunasekare M.T.K.,Tea Research Institute of Sri Lanka | Kottawa-Arachchige J.D.,Tea Research Institute of Sri Lanka | Paskarathevan R.,Tea Research Institute of Sri Lanka | And 3 more authors.
Euphytica | Year: 2011

A comprehensive knowledge on reproductive traits is a prerequisite in utilizing the existing tea germplasm effectively for crop improvement to develop superior planting material for grower acceptance and market profitability. The Sri Lankan tea germplasm was characterized based on reproductive traits viz. floral morphology, pollen biology, stigma receptivity and phenology of flowering and fruit set. The variability in floral morphology, especially the style morphological features, formed phenotypic clines rather than distinct groups. Studies on pollen biology and stigma receptivity revealed significant variability and asynchrony that could result unequal reproductive success among the genotypes. Four distinct patterns were predictable among the genotypes based on flower and fruit abundance and the time of flowering and fruit set. Three well marked flowering periods occurred in February to April, July and in November. Nonetheless, major flowering period coincided February and March in all the genotypes allowing free crossing between the different genotypes. Profuse mature fruit crop was obtained in February to May. Approximately 26% success was achieved in tea controlled hybridization programmes. Fruits carry two seeds on average and became mature in 8-9 months after pollination. Zygotic development in tea takes more than 1 month after pollination and early embryonic development continued for 4 months after pollination. The indexing of the morpho-physiological diversity and the phenological calendars of flowering and fruit set made available in the study are of significant importance in effective utilization of the tea germplasm for crop improvement. © 2011 Springer Science+Business Media B.V.

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