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Titre : Diversidad morfológica y variación isoenzimática de maíces nativos del altiplano centro-oriente del estado de Puebla

MORPHOLOGICAL DIVERSITY AND ISOZYME VARIATION OF MAIZE NATIVE TO THE CENTRAL-EASTERN HIGHLAND PLATEAU OF THE STATE OF PUEBLA

Auteur : Hortelano Santa Rosa, René

Etablissement de soutenance : Colegio de Postgraduados (COLPOS) Consejo Nacional de Ciencia y Tecnología (CONACYT)

Grade : Doctorado en Ciencias, especialista en Genética 2010

Résumé
This study aimed at quantifying and analyzing genetic diversity (at morphological an isozyme level) present today among native populations of maize (Zea mays L.) grown in the Central-Eastern highland plateau of the state of Puebla, and establishing relationships of similarity between those populations and the races reported for that area. The work was conducted in two stages : the first one consisted in the evaluation, in three localities, of 134 native populations, six representative accessions of the races Cónico, Cónico Norteño, Palomero Toluqueño, Chalqueño and its variants Chalqueño Palomo and Chalqueño Crema, and four commercial varieties recommended for the area. The design was a 12 × 12 simple lattice. During the growing season diverse phenotypic traits were measured, and 17 of those were retained for multivariate statistical analysis. The second stage corresponded to isoenzyme analysis, working with 51 native populations representing the groups detected through morphological analysis. Ten enzyme systems encoded by 18 loci were explored and a total of 52 alleles were found ; in addition, genetic diversity parameters were estimated based on allele frequencies. Results showed the existence of large phenotypic diversity among native populations. Even though such diversity could be clustered into five groups, there was a continuum of variation. The groups identified had genetic diversity comparable to maize from other parts of the country, with 2.83 alleles per locus, 89% of polymorphism and expected heterozygosity of 0.27 ; however, they had moderate genetic differentiation (0.085). The materials of the studied region showed greater morphological affinity to the Chalqueño race, particularly to the Chalqueño Crema check. At the isoenzyme level, the greatest similarity was with the racial check ’Chaqueño’ ; however, in both cases it was observed that significant divergence has occurred in relation to this race, suggesting that the studied native populations are under a continuous process of selection.

Mots clés : Zea mays L.. Isoenzimas. Poblaciones nativas. Diversidad fenotípica. Valles Altos. Raza Chalqueño. Isozymes. Native populations. Phenotypic diversity. Highlands. Chalqueño race.

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