Browsing by Author "Fernando, S.C."
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Item Efficient Method of Transporting Coconut (Cocos nucifera L.) Zygotic Embryos for Cryopreservation of Plumules by Encapsulation/Dehydration(2014) Bandupriya, H.D.D.; Fernando, S.C.; Verdeil, J.L.; Malaurie, B.Coconut is both socially and economically important crop in tropical and subtropical countries, thus the conservation of existing diversity of its germplasm is vital to maintain biodiversity, sustain crop production and utilisation of germplasm for crop improvement strategies. The recalcitrant storage behavior and large size of the coconut seed make it impossible to use as a germplasm storage material. Cryopreservation is an ideal means of long-term storage of germplasm which offers long-term storage capability with minimal storage space and maintenance requirements. The coconut embryo has been now adapted by various researchers for the purpose of germplasm exchange and it is now being routinely applied in germplasm collection and exchange activities with sufficient germination rates. The aim of the present study was to determine the effect of different coconut embryo transport! storage methods [as solid endosperm plugs under cold temperature, embryos cultured in Solidified Agar Medium (SAM) or KCI solution under room temperature] on cryopreservation of plumules using encapsulation/dehydration method. The results revealed that plumules excised from embryos transported/ stored in SAM and pretreated with 1.0M sucrose could be cryopreserved with 71.8% survival and 56% recovery rates. The survival and recovery could be further increased up to 77.5% and 65% respectively by supplementation of I.OM sucrose with 20 uM ABA.Item Histological analysis of plant regeneration from plumule explants of Cocos nucifera(2003) Fernando, S.C.; Verdeil, J.L.; Hocher, V.; Weerakoon, L.K.; Hirimburegama, K.Plant regeneration was achieved from plumules excised from mature zygotic embryos of a local coconut cultivar (Sri Lanka Tall). A detailed histological study was undertaken to gain a better understanding of the cellular changes that occur during plant regeneration from plumule tissues. This study led to the identification of the cellular origin, specific cell characterization and development pattern of embryogenic calluses. It also revealed that abscisic acid induces plant regeneration through somatic embryogenesis. The presence of incomplete somatic embryos that lacked shoot poles was also observed.Item In Vitro Characterization of Indigeneous Coconut Varieties (Cocos nucifera L.) of Sri Lanka for Water Stress Tolerance(2012) Fernando, S.C.; Santha, E.S.; Perera, S.A.C.N.; Dissanayake, H.D.M.A.C.; Meegahakumbura, M.G.M.K.; Perera, L.Coconuts show a remarkable yield drop due to long dry periods caused by global climatic changes.Thus, breeding for drought tolerance has become a priority in coconut breeding in Sri Lanka.Five coconut varieties indigenous to Sri Lanka, namely Ran thembili,Gon thembili, Porapol, Bodiri and Red dwarf were screened for their drought tolerance potential in vitro. Mature zygotic embryos collected from self pollinated nuts of each variety were germinated and developed into plants with one photosynthetic leaf in Y3 medium.Water stress condition was induced by application of Polyethylene Glycol(PEG) into the culture medium.The level of PEG in culture medium was gradually increased from 2% to 7% until the plants showed water stress symptoms in leaves; yellowing and necrosis.More than 75% of zygotic embryos of all tested coconut varieties successfully gemJinated in vitro and developed into plants. Plants of all tested coconut varieties survived water stress caused by 4% to 6% PEG and the percentages of plant survival at different levels of PEG varied among different coconut varieties. Variety Ran thembili showed the highest survival rate(27%) at 6% PEG and overall best plant growth perfomJances at 4% PEG among the five coconut varieties tested. Red dwarf showed the lowest survival rate at 4% to 6% PEG indicating its susceptibility to water stress. Among the coconut varieties tested, zygotic embryos of Ran thembili showed the highest drought tolerance potential.Item Use of Arabinogalactan Protien in Coconut (Cocos Nucifera L.)Tissue Culture:An Alternative Approach for Improved Tissue Response(2011) Fernando, S.C.; Samarajeewa, D.A.D.S.; Liyanagedara, L.G.N.H.K.Arabinogalactan proteins (AGPs) are extra-cellular proteins involved in plant growth and development. The effects of these proteins on in vitro response of different species are well documented. This study assessed for the first time the role of AGPs on tissue culture of coconut,a highly recalcitrant species in vitro. Coconut (Sri Lanka Tall) plumules were cultured in medium containing 2, 4-dichlorophenoxyaceticacid (2,4-0) for callogenesis. Calli were multiplied by subculturing onto freshly prepared callusing medium.Somatic embryos were induced by transferring of calli to medium with 2/3 concentration of initial 2,4-0 and matured by subsequent transferring to medium without any hOlIDones. Embryos were converted in the presence of gibberelic acid. Arabic gum (I-50 mgC·) was used as the main source of AGP. Alternatively, different AGP sources like Larch wood gum, carrot seeds and defatted coconut kernel were also assessed. Arabic gum in callusing medium resulted in early callogenesis from 20-40% plumules compared to 10% in the control. However, it did not have a significant effect on final callusing efficiency.Its presence in somatic embryogenesis medium showed a significantly higher mass of embryogenic structures per an embryogenic clump (33.3-50.5mg) when compared to the control (26.9mg).The best result was obtained at 10mgC· Arabic gum.All AGP sources except Larch wood gum had positive effects on somatic embryogenesis.Among them, defatted coconut kernel(25-50mgL-1) showed the best results giving 70% cultures with embryogenic structures compared to 37 % in control.However,so far,the positive effect of AGP did not reflect in plant regeneration efficiency.