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Studies on cocoyam (Xanthosoma spp.) in Nicaragua, with emphasis on Dasheen mosaic virus

Reyes Castro, Guillermo (2006). Studies on cocoyam (Xanthosoma spp.) in Nicaragua, with emphasis on Dasheen mosaic virus. Diss. (sammanfattning/summary) Uppsala : Sveriges lantbruksuniv., Acta Universitatis Agriculturae Sueciae, 1652-6880 ; 2006:7
ISBN 91-576-7056-0
[Doctoral thesis]

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Cocoyam, Xanthosoma spp., is cultivated in tropical regions as a source of carbohydrates for human nutrition, for animal feed, and cash income for the farmers. It is the most important export crop of all the root and tuber crops grown in Nicaragua, but the national yield and total planted area have drastically decreased during the last few years. The crop has received little research attention, and previous to the studies presented in this thesis there was hardly any information available regarding the number of genotypes cultivated in the country, the agronomic performance of the different genotypes, which diseases that infect the crop, and to what extent these diseases influence the yield. Three cocoyam genotypes were evaluated regarding agronomic traits in four field locations during two years. Significant interactions between genotype and location as well as between genotype and year were found for many of the traits. A differential response of the genotypes to the varying climatic conditions at the locations is one of the possible causes of these interactions. Different harvest times for the three genotypes are suggested, due to differences in time to reach the maximum growth. Dasheen mosaic virus (DsMV) is the most important virus that infects cocoyam. Virus-free plants were produced through meristem culture, and protocols for the regeneration of plants via callus and protocorm-like structures were established. Although a genotypic response to tissue culture was observed, all the tested genotypes produced shoots from meristem and from meristem-derived calli. Under field conditions the virus-free plants performed better, regarding yield, than infected in vitro plants. The fact that the plants were virus-free could not, by itself, explain the yield increase, suggesting that the process of in vitro re-invigoration also played an important role. Aphis gossypii was the only winged aphid observed during the field trial, suggesting that this insect is the virus-transmitting vector. cDNA fragments containing the coat protein (CP) and 3’-UTR regions of nine DsMV isolates were molecularly characterised. One isolate had a 19 aa long deletion in the N-terminus of the CP region. The Nicaraguan isolates formed two subgroups correlated with geographic origin of the cocoyam genotypes. Author’s address: Guillermo Reyes Castro, Facultad de Agronomía, Universidad Nacional Agraria (UNA), km 12 ½ Carretera Norte, Apdo. 453, Managua, Nicaragua. E-mail: Guillermo.Reyes.Castro@una.edu.ni

Authors/Creators:Reyes Castro, Guillermo
Title:Studies on cocoyam (Xanthosoma spp.) in Nicaragua, with emphasis on Dasheen mosaic virus
Series Name/Journal:Acta Universitatis Agriculturae Sueciae
Year of publishing :January 2006
Number of Pages:33
ALLI. Reyes-Castro, G., Nyman, M. & Rönnberg-Wästljung, A.C. 2005. Agronomic performance of three cocoyam (Xanthosoma violaceum Schott) genotypes grown in Nicaragua. Euphytica, 142, 265-272. II. Reyes, G. & Nyman, M. Direct and indirect plant regeneration from meristem and shoot apex of cocoyam (Xanthosoma spp.) Manuscript. III. Reyes, G., Rönnberg-Wästljung, A.C. & Nyman, M. 2006. Comparison of field performance between Dasheen mosaic virus-free and virus-infected in vitro plants of cocoyam (Xanthosoma spp.) in Nicaragua. Experimental Agriculture, 42(3). In press. IV. Reyes, G., Ramsell, J., Nyman, M & Anders Kvarnheden. Molecular characterisation of Dasheen mosaic virus isolates from cocoyam (Xanthosoma spp) in Nicaragua. Manuscript.
Place of Publication:Uppsala
ISBN for printed version:91-576-7056-0
Publication Type:Doctoral thesis
Full Text Status:Public
Agris subject categories.:F Plant production > F30 Plant genetics and breeding
H Protection of plants and stored products > H20 Plant diseases
Subjects:Not in use, please see Agris categories
Agrovoc terms:xanthosoma, taro, plant viruses, plant diseases, genotypes, genotype environment interaction, field experimentation, nicaragua
Keywords:Cocoyam, genotype × environment interaction, DsMV, virus-free plants production, effect on yield, molecular characterisation.
Permanent URL:
ID Code:1028
Department:(NL, NJ) > Dept. of Plant Biology and Forest Genetics (until 131231)
Deposited By: Guillermo Reyes
Deposited On:25 Jan 2006 00:00
Metadata Last Modified:02 Dec 2014 10:09

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