Browsing by Author "Lalith Perera"

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    Ambiguous genetic relationships among coconut (Cocos nucifera L.) cultivars: the effects of outcrossing, sample source and size, and method of analysis
    (2010) Margarita Mauro-Herrera; Alan W. Meerow; Lalith Perera; Joanne Russell; Raymond J. Schnell;
    A prior analysis of eight coconut cultivars with 15 microsatellite (SSR) markers drew unexpected relationships between two of the out-crossing tall cultivars evaluated: ‘Atlantic Tall’ and ‘Panama Tall’. We further investigated the relationships between these eight cultivars by increasing the number of individuals studied (particularly for ‘Atlantic Tall’ and ‘Panama Tall’), by including 28 more molecular markers, and by adding two other cultivars to our analysis. Our results show that five to ten coconut individuals do not represent a dependable sample to withdraw conclusions regarding cultivar/variety relationships, particularly when studying out-crossing genotypes. As suggested in the prior study, a high level of hybridization was observed between the ‘Atlantic Tall’ and ‘Panama Tall’ cultivars. However, at this time we were able to identify distinct groups for each one of these two cultivars. The two clustering methods used (Neighbor Joining, NJ and Unweighted Pair Group Method with Arithmetic mean, UPGMA) produced dendrograms that resolved contrasting cultivar relationships, especially for the ‘Atlantic Tall’ and ‘Panama Tall’ cultivars. We discuss the implications of our results in regard to current scenarios of coconut domestication and future considerations when assessing genetic relationships among different varieties.
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    Coconut Palms on the Edge of the Desert:Genetic Diversity of Cocos nucifera L. in Oman
    (2011) Lalith Perera; Luc Baudouin; Roland Bourdeix; Anwar Bait Fadhil; Fabien C.C.Hountondji; Abdulaziz Al-Shanfri
    In the Gulf region, coconuts are almost exclusively produced from palms growing in the Sultanate of Oman, particularly in the extreme south-eastern coastal plain of the Dhofar Governorate,and specifically within the city limits of Salalah, between the Jebel and the sea. The importance of these coconuts is not only agricultural; historically, the Dhofar palms provided the basic materials to build boats for fishermen and traders on, around and eventually beyond the Indian Ocean. Coconut palms are now one of the main symbols of Salalah city and playa role in both the tourist industry and urban landscaping. In early 2009, twenty-nine sites, representing Oman coconuts on beaches and cultivated lands were chosen from the Dhofar region.COGENT descriptors and DNA analysis were used for the purpose of identifying coconut germplasm available in Oman. The presence was confirmed of varieties that were imported during the 1980s, such as Yellow Dwarf, Green Dwarf and King coconut from Sri Lanka, as well as Malayan Yellow Dwarf and Fl hybrids. The local Oman Tall has the same phenotypic characteristics as other coconuts of South Asia, East and West Africa,the Caribbean and the Atlantic coast of South America. Microsatellite markers, however, reveal a substantial genetic contribution of the South-East Asian coconuts, at levels that are comparable to those found in the Comoros and Madagascar coconuts. Hypotheses about the ancestry of the Oman Tall coconuts are discussed; two genepools are indicated, consecutively involving natural selection, dissemination by floating, domestic selection and dispersal by boat.
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    Detection of Weligama Coconut Leaf Wilt Disease Phytoplasma by Real-Time Polymerase Chain Reaction
    (2020) Wijesekara, H.T.R.; Perera, S.A.C.N.; Bandupriya, D; Meegahakumbura, M.K; Lalith Perera
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    Hybrid Testing and Variety Identification of Coconut (Cocos nucifera L.) in Sri Lanka Using Microsatellite Markers
    (2010) Lalith Perera
    Currently, there is no reliable method for confirmation of the identity of coconut cultivars and the legitimacy of coconut hybrids. This makes serious problems in coconut breeding and seed production as the identity of coconut cultivars/hybrids can only be approximated at the very late stages of the growth based on reproductive traits owing to long juvenile period and the perennial nature of coconut. A microsatellite (SSR) marker based approach was used to develop an identification method for coconut varieties; Sri Lanka Tall. Sri Lanka Green Dwarf and Sri Lanka Yellow Dwarf, the key parents in the breeding programmes and tall x dwarf hybrids among them, using 18 coconut specific SSR primers. The validity of using yellow colour petiole as a phenotypic marker for the identification of dwarf yellow was also investigated. Two SSR primers. namely CAC20 and CNZ6 have exhibited the potential for distinguishing coconut varieties used as parents in the breeding programme and for confinning hybridity. It was revealed that yellow colour petiole is not a reliable marker for identification of dwarf yellow variety.
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    The Most Frequent Agronomic Practices Used by the Coconut Farmers in the "Coconut Triangle" of Sri Lanka
    (2018) Baptiste Legrand; Angelique Perraut; Chaminda Herath; Rusitha Wijekoon; Lalith Perera
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    Some progressive steps in coconut research and development in Sri Lanka through utilization of molecular markers
    (Indian Society for Plantation Crops, 2014-04) Lalith Perera
    Coconut is the sole species of genus Cocos and as such breeding of coconut is limited to the intra-specific level. Furthermore, the long life cycle, massive stature, highly heterozygous nature, lack of vegetative propagation method, limited number of seeds produced per year and bulkiness of seeds, limit the use of many traditional breeding methods employed in other crops in coconut breeding. Obtaining pure line from heterozygous coconut remained unrealistic because of the long vegetative phase. Thus coconut breeding is confined to mass selection of phenotypically superior parent palms, and to inter and intra-varietal hybridization. All these constraints in coconut breeding make the use of molecular breeding techniques highly attractive. Although identifying molecular markers linked to useful traits and characters to strengthen and fasten the selection and breeding of coconut looks the main goal of using markers, they can be efficiently used for many other applications. This article deals with some other useful applications of molecular markers practically used in the coconut breeding programme in Sri Lanka.
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    Some progressive steps in coconut research and development in Sri Lanka through utilization of molecular markers
    (Indian Society for Plantation Crops, 2014-04) Lalith Perera
    Coconut is the sole species of genus Cocos and as such breeding of coconut is limited to the intra-specific level. Furthermore, the long life cycle, massive stature, highly heterozygous nature, lack of vegetative propagation method, limited number of seeds produced per year and bulkiness of seeds, limit the use of many traditional breeding methods employed in other crops in coconut breeding. Obtaining pure line from heterozygous coconut remained unrealistic because of the long vegetative phase. Thus coconut breeding is confined to mass selection of phenotypically superior parent palms, and to inter and intra-varietal hybridization. All these constraints in coconut breeding make the use of molecular breeding techniques highly attractive. Although identifying molecular markers linked to useful traits and characters to strengthen and fasten the selection and breeding of coconut looks the main goal of using markers, they can be efficiently used for many other applications. This article deals with some other useful applications of molecular markers practically used in the coconut breeding programme in Sri Lanka.