Browsing by Author "Hettiarachchi, G.H.C.M."

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    Analysis of OsBBX13 Gene Responses to Salinity Stress Tolerance in Oryza sativa (Rice
    (Uva Wellassa University of Sri Lanka, 2020) Bandara, K.G.W.W.; Wijesundera, W.S.S.; Hettiarachchi, G.H.C.M.
    The B-box (BBX) proteins are a subgroup of zinc finger transcription factors that contain one or two B-box domains. The B-box domain is a conserved motif. Genes that encode for BBX proteins are highly conserved across all multicellular species. BBX proteins were first identified in Arabidopsis thaliana that play a significant role in light and abiotic stress signalling. In Oryza sativa (rice) only a few BBX genes have been identified which are involved in flowering. Our previous study on ortholog search identified OsBBX13 as a functional ortholog of the Arabidopsis AtBBX21 gene that is involved in light and abiotic stress regulation. This study aimed to conduct an in silico analysis of the OsBBX13 gene promoter to identify the presence of abiotic stress-responsive elements and to study the expression of the OsBBX13 gene under salinity stress. Promoter sequence (1.0 kb upstream of translation start site) of the OsBBX13 gene was retrieved from the Rice Annotation Project Database (RAP-DB). The tools of PlantCARE and New PLACE were used for scanning of abiotic stress-responsive cis-elements present on the promoter region of OsBBX13. The salinity stress-responsive elements, MYBCORE and GT1GMSCAM4, and Abscisic acid-responsive element (ABRE) which regulates the dehydration and salinity responses were identified in OsBBX13 promoter region. Quantitative Real Time PCR analysis of 7 days old rice seedlings exposed to 200 mM NaCl stress showed significant up-regulation of the OsBBX13 gene compared to the control. All these findings together suggested that the OsBBX13 gene is involved in salinity stress responses in rice. Keywords: BBX proteins, OsBBX13, Salinity stress, Abiotic stress
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    DNA Based Analysis for Distribution of Meloidogyne Species in Selected Crop Plants in Different Geographical Locations in Sri Lanka
    (Uva Wellassa University of Sri Lanka, 2018) Paramalingam, D.; Hettiarachchi, G.H.C.M.; Rajapakse, R.V.D.U.P.
    Meloidogyne species are highly destructive endoparasitic nematodes with a wide host range. Molecular identification of the Meloidogyne species that infect crop plants was performed in this study using Meloidogyne infected 28 root samples collected from four different crops in five different geographical locations in Sri Lanka during May to July in 2017; Passara (6.934909, 81.152698) tomato, Thanamalwila (6.439755, 81.133397) chili, Pallekele (7.280104, 80.702034) capsicum, Vellankulam (9.186089, 80.126481) chili, Kaluwanchikudy (7.529373, 81.794609) chili and Kaluwanchikudy (7.529373, 81.794609) okra. Polymerase chain reactions were carried out in these samples with MF/MR primer pairs, C2F3/1108 primer pairs and 194/195 primer pairs. Genus specific universal primers MF/MR amplified, 500 by fragment of ribosomal DNA of Passara tomato, Thanamalwila chili, Pallekele capsicum, Vellankulam chili and Kaluwanchikudy chili samples representing the presence of genus Meloidogyne. Primer pair C2F3/1108 amplified, 705 by fragment of mitochondrial DNA of Thanamalwila chili, Pallekele capsicum, Vellankulam chili and Kaluwanchikudy chili samples representing the presence of Meloidogyne enterolobii. Primer pair 194/195 amplified, 700 by fragment of ribosomal DNA of Passara tomato and Kaluwanchikudy chili samples representing the presence of Meloidogyne hapla. A mixed population of M. enterolobii and M. hapla was resulted in Kaluwanchikudy chili. Kaluwanchikudy okra did not produce any band with any primer pair amplifications revealing that it had unknown species. This study confirms the expansion of the distribution of M enterolobii and M. hapla in Sri Lanka in recent years. M. enterolobii was present in all the chili/capsicum samples tested and this is the first report of its availability in infested chili/capsicum plants in Sri Lanka.