Articles
VARIABILITY OF VENEZUELAN GUAVA GEOGRAPHIC LANDRACES EMPLOYING PHENOTYPIC MARKERS
Article number
849_9
Pages
87 – 94
Language
English
Abstract
When the Spanish conquerors became acquainted with tropical America, they identified and described numerous types of guavas, which varied in color, form, and flavor.
Some of these were disseminated to the rest of the world and yielded the varieties cultivated nowadays.
Commercial guava orchards are located mainly in the Venezuelan plains, and rely mainly on a few varieties imported over 40 years ago.
However, aside from the varieties grown in commercial plantations, most of the Venezuelan territory comprises numerous landraces.
Hence, due to the lack of national varieties and despite the huge, but unexploited variability of guava germplasm, we sampled guava landraces across the country and characterized them using 23 UPOV descriptors.
Guava landraces were collected in an altitude gradient ranging from 0 to 2000 m.a.s.l. and in a variety of ecosystems, the vast majority of them associated with human settlements.
The 100 collected samples were evaluated by phenotypic markers, and revealed an elevated degree of polymorphism.
The most informative markers, based on the degree of variability, were those related to fruit characters: number of seeds and color of the skin and the flesh.
The analyses also revealed a distribution pattern apparently related with certain regions of the country that show more abundance and/or more diversity of phenotypes.
This may be related to the reproductive biology of P. guajava (selfing or outcrossing), its biotic and environmental interactions, and anthropic factors.
The collected guavas with their broad variability constitute a valuable germplasm resource for the development of genetic improvement programs.
Likewise, the variety of phenotypes and their geographical distribution suggest that the north of South America might represent the centre of origin of guava; however, this finding requires confirmation through a detailed and comprehensive phylogenetic analysis employing traditional and molecular biology tools.
Some of these were disseminated to the rest of the world and yielded the varieties cultivated nowadays.
Commercial guava orchards are located mainly in the Venezuelan plains, and rely mainly on a few varieties imported over 40 years ago.
However, aside from the varieties grown in commercial plantations, most of the Venezuelan territory comprises numerous landraces.
Hence, due to the lack of national varieties and despite the huge, but unexploited variability of guava germplasm, we sampled guava landraces across the country and characterized them using 23 UPOV descriptors.
Guava landraces were collected in an altitude gradient ranging from 0 to 2000 m.a.s.l. and in a variety of ecosystems, the vast majority of them associated with human settlements.
The 100 collected samples were evaluated by phenotypic markers, and revealed an elevated degree of polymorphism.
The most informative markers, based on the degree of variability, were those related to fruit characters: number of seeds and color of the skin and the flesh.
The analyses also revealed a distribution pattern apparently related with certain regions of the country that show more abundance and/or more diversity of phenotypes.
This may be related to the reproductive biology of P. guajava (selfing or outcrossing), its biotic and environmental interactions, and anthropic factors.
The collected guavas with their broad variability constitute a valuable germplasm resource for the development of genetic improvement programs.
Likewise, the variety of phenotypes and their geographical distribution suggest that the north of South America might represent the centre of origin of guava; however, this finding requires confirmation through a detailed and comprehensive phylogenetic analysis employing traditional and molecular biology tools.
Authors
Y. Aranguren, C. Valecillos, G. Fermin
Keywords
plant diversity, germplasm, Psidium guajava, UPOV, tropical crops
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