Comparative analysis of phenotypic and genotypic diversity among plantain landraces (Musa spp., AAB group) |
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Authors: | H K Crouch J H Crouch S Madsen D R Vuylsteke R Ortiz |
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Institution: | Plantain and Banana Improvement Program, Crop Improvement Division, International Institute of Tropical Agriculture (IITA), P.M.B. 5320, Oyo Road, Ibadan, Nigeria Fax: 91 40 329 6182; e-mail: J.H.CROUCH@CGIAR.ORG, Present addresses: J.H. Crouch, Genetic Resource and Enhancement Program, International Crops Research Institute for the Semi-Arid Tropics, Patancheru 502 324, Andhra Pradesh, India, NG SAS Instituto, K?bmagergade 7–9, DK-1150 K?benhavn K, Denmark, DK
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Abstract: | Genetic diversity amongst 76 plantain landraces has been studied using RAPD analysis at two levels of intensity and compared
with groupings based on phenotypic indices and morphotype. There was a good correlation (R2=0.78) between estimates of genetic diversity based on 76 RAPD bands and 164 RAPD bands. However, there was a poor correlation
between RAPD-based estimates of genetic diversity and a phenotypic index based on agronomic characters. There was also a poor
correlation between RAPD analyses and morphotype group (based on bunch type and stature). These results suggest that the traditional
designations of plantain landraces based on morphotype do not provide a true reflection of overall genetic divergence. Similarly,
classification systems using phenotypic indices based on agronomic characters may not provide accurate taxonomic differentiation.
The level of genetic divergence within morphogroups based on bunch type suggests that True Horn plantains are derived from
False Horn plantains which in turn are derived from French plantains. Genetic divergence was found to be generally quite low
within the plantain landrace genepool, which is consistent with the proposed evolution of this germplasm through somatic mutation
of a relatively small number of introductions. However, putative synonyms/duplicates have been shown to be genetically distinct.
In contrast, a group of 12 landraces have been identified that are highly distinct from one another (showing 20–35% dissimilarity).
Fertile members of this group may be useful for generating genetically diverse 2x and 4x breeding populations that can be
used in breeding secondary triploid hybrid plantain varieties.
Received: 8 January 2000 / Accepted: 2 March 2000 |
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Keywords: | Plantain Musa RAPD Phenotype Breeding |
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