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Abstract

Annona muricata is an important tropical crop whose fruits are prized for their high nutritional and medicinal value. The fruits have great potential serving as raw material for the production of juice, beverages and wine. They can also serve as a natural source of antioxidants that could be harnessed as dietary supplements for the treatment of cancer, parasitic infections and other diseases. To unlock the amount of genetic differences prevalent in natural accessions as a prerequisite and vital guide for germplasm characterization and further improvement randomly amplified polymorphic DNA (RAPD) and morphological markers were used in this study to evaluate genetic diversity amongst 42 accessions of the plant collected from 4 distinct geographical zones of Nigeria. The accessions were studied in situ at flowering and morphological data collected on length, width and area of leaf, plant height, trunk length, trunk type, stem diameter, number of flowers and number of fruits. Data obtained were subjected to analysis of variance and factor analysis based on principal component analysis (PCA), all using Genstat Discovery Edition 4 software. For molecular studies, DNA was extracted from young healthy leaves and 8 polymorphic decamer primers (OPB10, OPB14, OPB17, OPH05, OPH08, OPT04, OPT05 and OPT06) were individually utilized in a PCR cocktail after which products with each primer were run on agarose gel (1.5%). Positions of informative bands were scored from the gel documentation picture and analyzed using Darwin for Windows Software version 6. Results of the morphological evaluations indicated that number of flowers and fruits differed significantly (p<0.001) while all other traits were not significantly different (p>0.05). A total of 71.38% of the variations was explained by 3 principal components (PC1-32.40%, PC2-24.33% and PC3-14.65%) with leaf area, leaf length and leaf width as the most prominent characters. From the molecular analyses, a total of 65 bands were obtained. Of these, 59 (90.77%) were polymorphic while 6 (9.23%) were monomorphic. An average of 8.13 bands was obtained per primer and 7.38 of these were polymorphic with the average size of the bands being 200>1000 bp. OPT04 primer amplified the lowest (6) number of bands out of which 5 (83.33%) were polymorphic while OPH05 and OPT06 amplified the highest (9 and 11) with all bands (100%) being polymorphic. A total of 14 (21.54%) unique bands were also detected. Taken together, the results reported here are indications that there is a high amount of exploitable genetic diversity in natural accessions of A. muricata which will guide selection of useful germplasm for improved fruit quality and production of bioactive molecules for use in food and pharmaceutical industries.

Biography

Nneka Constance Ogbonna is a Postgraduate Student in the Department of Genetics and Biotechnology, University of Calabar, Calabar, Cross River State, Nigeria. She was born in Nigeria on 18th June, 1987 and bagged a Bachelor of Science degree (Second Class Upper Division) in Plant Science and Biotechnology from Abia State University, Uturu, Nigeria in 2010. She has gained research and laboratory experience from reputable establishments including the National Root Crops Research Institute, Umudike (Biotechnology and Tissue Culture Laboratory Division) and International Institute of Tropical Agriculture (IITA), Ibadan, Nigeria (Bioscience Centre). Her research interest centers on molecular characterization of useful germplasm of medicinal and industrial importance. She is very open to support and collaborations and has Co-Authored articles for publication in reputable journals. She takes extra interest in event planning, cooking and research.

Email: gen_uyoh@yahoo.com