Horticultural Crop Research and Development Institute

Peradeniya, Sri Lanka

Horticultural Crop Research and Development Institute

Peradeniya, Sri Lanka
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Hurtado M.,Polytechnic University of Valencia | Vilanova S.,Polytechnic University of Valencia | Plazas M.,Polytechnic University of Valencia | Gramazio P.,Polytechnic University of Valencia | And 3 more authors.
PLoS ONE | Year: 2012

Eggplant (Solanum melongena L.) was domesticated in the Indo-Birmanian region, which is also the primary center of diversity for this crop. From there eggplant spread to other regions, and diversity accumulated in several secondary centers of diversity. We have assessed the diversity and relationships of 52 accessions of eggplant from three geographically distant secondary centers of diversity (China, Spain, and Sri Lanka) using 28 morphological descriptors and 12 highly polymorphic genomic SSRs. A wide variation was found for most morphological traits, and significant differences among the three centers of diversity were detected for 22 of these traits. The PCA analysis showed that eggplants from the three origins were morphologically differentiated, and accessions from each of the three secondary centers of diversity presented a typical combination of morphological characteristics. In this respect, discriminant analysis showed that accessions could be correctly classified to their origin using only six traits. The SSR characterization identified 110 alleles and allowed obtaining a unique genetic fingerprint for each accession. Many alleles were found to be private to each origin, but no universal alleles were found for any of the origins. The PCA analysis showed that the genetic differentiation among origins was less clear than for morphological traits, although the analysis of the population structure shows that accessions mostly group according to the origin, but also provides evidence of migration among the three secondary centers of diversity. The genetic diversity (HT) within each origin was high, ranging between HT = 0.5400 (Sri Lanka) and HT = 0.4943 (China), while the standardized genetic differentiation (G'ST) among origins was moderate (G'ST = 0.2657). The correlation between morphological and SSR distances was non-significant (r = 0.044), indicating that both data are complementary for the conservation of germplasm and breeding of eggplant. These results are relevant for the management of genetic resources, breeding programmes, and evolutionary studies of eggplant. © 2012 Hurtado et al.

Ranil R.H.G.,University of Peradeniya | Niran H.M.L.,Agriculture Research Station | Plazas M.,Polytechnic University of Valencia | Fonseka R.M.,University of Peradeniya | And 6 more authors.
Scientia Horticulturae | Year: 2015

Solanum torvum is a highly vigorous relative of eggplant that is resistant to a number of harmful soil-borne diseases and is compatible for grafting with eggplant. Being a potential rootstock, this plant frequently presents poor and erratic germination, which makes its practical use difficult. We used an L8 (27) orthogonal array design to evaluate the primary effects of seven factors (soaking of seeds, scarification with sodium hypochlorite (NaClO), application of gibberellic acid (GA3), use of potassium mitrate (KNO3) as a moistening agent, cold stratification, application of a heat shock, and light irradiation during germination) at two levels (L0 and L1) using four germination parameters (early and final germination, germination rate and vigour index) in fresh S. torvum seeds. S. torvum seeds had a strong dormancy with no germination in the untreated seeds and high early and final germination (approximately 100%) in certain treatments. An evaluation of the main effects revealed highly positive effects on germination from seed soaking, and the use of GA3, KNO3, and light irradiation, whereas NaClO scarification had a negative effect. The application of cold stratification and heat shock treatments also had a positive effect on seed germination but to a lesser extent than the other treatments. An improved proposed protocol that consisted of subjecting seeds to soaking, the application of GA3 and KNO3, cold stratification, heat shock, and light irradiation was validated and demonstrated to be highly effective, with seed germination success greater than 60% being observed at 3 days and final germination reaching a plateau at 6 days. A second validation experiment using a commercial growing substrate also showed a high emergence (approximately 50%) at 7 days and a final germination of approximately 80% was recorded with application of the improved protocol. The seed germination protocol that we have developed will facilitate the use of S. torvum as a rootstock for eggplant and its use in breeding programmes. Our results also reveal that orthogonal array designs are a powerful tool for establishing improved protocols for seed germination. © 2015 Elsevier B.V.

Plazas M.,Polytechnic University of Valencia | Vilanova S.,Polytechnic University of Valencia | Gramazio P.,Polytechnic University of Valencia | Rodriguez-Burruezo A.,Polytechnic University of Valencia | And 9 more authors.
Journal of the American Society for Horticultural Science | Year: 2016

Wild relatives represent a source of variation for many traits of interest for eggplant (Solanum melongena) breeding, as well as for broadening the genetic base of this crop. However, interspecific hybridization with wild relatives has been barely used in eggplant breeding programs. As initiation of an introgression breeding program we performed 1424 interspecific hybridizations between six accessions of eggplant from the Occidental and Oriental groups and 19 accessions of 12 wild species from the primary (Solanum incanum and Solanum insanum), secondary (Solanum anguivi, Solanum dasyphyllum, Solanum lichtensteinii, Solanum linnaeanum, Solanum pyracanthos, Solanum tomentosum, and Solanum violaceum), and tertiary (Solanum elaeagnifolium, Solanum sisymbriifolium, and Solanum torvum) genepools. Fruit set, hybrid seed, and seed germination were obtained between Solanum melongena and all wild species of the primary and secondary genepools. The highest fruit set percentage and quantity of seeds per fruit were obtained with the two primary genepool species S. incanum and S. insanum as well as with some secondary genepool species, like S. anguivi, S. dasyphyllum, or S. lichtensteinii, although some differences among species were observed depending on the direction of the hybridization. For small-fruited wild species, the number of seeds per fruit was lower when using them as maternal parent. Regarding tertiary genepool species, fruit set was obtained only in interspecific hybridizations of eggplant with S. sisymbriifolium and S. torvum, although the fruit of the former were parthenocarpic. However, it was possible to rescue viable interspecific hybrids with S. torvum. In total we obtained 58 interspecific hybrid combinations (excluding reciprocals) between eggplant and wild relatives. Some differences were observed among S. melongena accessions in the degree of success of interspecific hybridization, so that the number of hybrid combinations obtained for each accession ranged between 7 (MEL2) and 16 (MEL1). Hybridity of putative interspecific hybrid plantlets was confirmed with a morphological trait (leaf prickliness) and 12 single nucleotide polymorphism markers. The results show that eggplant is amenable to interspecific hybridization with a large number of wild species, including tertiary genepool materials. These hybrid materials are the starting point for introgression breeding in eggplant and in some cases might also be useful as rootstocks for eggplant grafting. © 2016, American Society for Horticultural Science. All right reserved.

Ratnayake R.M.R.N.K.,University of Peradeniya | Daundasekera W.A.M.,University of Peradeniya | Ariyarathne H.M.,Horticultural Crop Research and Development Institute | Ganehenege M.Y.U.,University of Peradeniya
Australasian Plant Pathology | Year: 2016

Silicon (Si) has been exploited for its beneficial effects in terms of disease control in many plants. Added Si was found to accumulate beneath the cuticle and act as a barrier against pathogen penetration, and also induce biochemical defense responses in plants. This study investigated the effect of soluble silicon (Si) supply on biochemical defense responses against powdery mildew pathogen (Erysiphe sp.) in bitter gourd (Momordica charantia L.), an intermediate Si accumulator. Supplying the sand-based growth medium with 200 ppm potassium silicate (Si+) significantly reduced the severity of powdery mildew infections, elevated the activities of enzymes peroxidase, polyphenol oxidase and pathogenesis-related proteins; chitinase and β-1,3-glucanase in bitter gourd leaves after challenged by Erysiphe sp. compared with those grown in control mix (Si−). After 7 weeks growth in Si-amended medium, leaves accumulated nearly seven times as much silicon (3.36 % dry weight) as those grown in control mix (0.44 % dry weight). The total Si content in leaves gradually decreased after the Si amendment was ceased. Si + plants exhibited a stronger antifungal activity against Cladosporium cladosporioides. Three zones with antifungal activity were revealed after separation of methanolic leaf extracts on thin-layer chromatography plates, out of which one compound was found to have induced by Si and/or Erysiphe infection, and another induced only by Si amendment. These results suggest that Si would play an active role in strengthening resistance in bitter gourd plants against powdery mildew by stimulating expression of several biochemical defense reactions. © 2016, Australasian Plant Pathology Society Inc.

Piyasena K.G.N.P.,Sri Lanka Institute of Fundamental Studies | Wickramarachchi W.A.R.T.,Horticultural Crop Research and Development Institute | Kumar N.S.,Sri Lanka Institute of Fundamental Studies | Jayasinghe L.,Sri Lanka Institute of Fundamental Studies | Fujimoto Y.,Tokyo Institute of Technology
Mycology | Year: 2015

A fungal endophyte isolated from the leaves of the allelopathic plant Amaranthus viridis of the family Amaranthaceae was identified as Chaetomium globosum through molecular means using internal transcribed spacer (ITS) region of rDNA gene. This is the first report of the isolation of C. globosum from Amaranthaceae. Chromatographic separation of the EtOAc extract of the fungal fermentation in potato dextrose broth yielded two known chlorine-containing azaphilone derivatives, chaetomugilin D (1) and chaetomugilin J (2). Compounds 1 and 2 were found to show phytotoxic activity in the lettuce (Lactuca sativa) seed germination bioassay. The IC50 values of 1 and 2 for root growth inhibition were 24.2 and 22.6 ppm, respectively, while IC50 values for shoot growth inhibition were 27.8 and 21.9 ppm, respectively. Phytotoxic activities of the chaetomugilin group of compounds have been reported for the first time, although their antifungal, antimicrobial and cytotoxic activities are known. © 2015 The Author(s). Published by Taylor & Francis

Ratnasekera D.,Ruhuna University | Perera U.I.P.,Ruhuna University | He Z.,Horticultural Crop Research and Development Institute | Senanayake S.G.J.N.,Ruhuna University | And 3 more authors.
Weed Biology and Management | Year: 2014

Weedy rice (Oryza sativa f. spontanea) is a notorious weed that infests paddy fields worldwide. Understanding the morphological variation pattern of this weed in a given rice-planting region will facilitate its effective management and use. Here, 29 populations, covering nearly all the rice-cultivation regions in Sri Lanka, were characterized in a common-garden cultivation experiment that was based on 13 morphological traits. The variation level of the weedy rice populations was considerably high, as estimated by the Simpson and Shannon-Weaver indices. An ANOVA revealed a higher level of among-population variation than within-population variation. Seed shattering was the most variable trait and the seed length and width were the least variable traits, as indicated by their coefficient of variation. The results of the principal component analysis, in which the first two principal components represented 57.5% of the total variation, indicated the important role of such traits as plant height, seed weight and number of tillers and panicles in the divergence of the weedy rice populations. However, the variation was not associated with their geographical locality. Knowledge of such a morphological variation pattern provides opportunities to design strategic management methods for weedy rice control in Sri Lanka, in addition to the proper use of it as a genetic resource for rice improvement. © 2014 Weed Science Society of Japan.

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