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Titre : Diversidad de maíces nativos de tres nichos ecológicos del altiplano poblano-tlaxcalteca

DIVERSITY OF MAIZE NATIVE TO THREE ECOLOGICAL NICHES FROM PUEBLA AND TLAXCALA HIGHLANDS

Auteur : Alvarado Beltrán, Gregorio.

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

Grade : Doctorado en Ciencias, especialista en Genética 2010

Résumé
In order to assess the existing level of morphological and genetic diversity of maize native to the Libres, Mazapiltepec and Huamantla ecological niches in the states of Puebla and Tlaxcala, México, this research was carried out. The study was divided into two stages. The first stage included a morphological characterization, evaluating 134 landraces native to the studied region, seven racial checks and three commercial checks under a simple 12 × 12 lattice experimental design with two replications at three localities, through the use of 21 morphological traits. The second stage consisted in an isozymatic analysis over 49 representative landraces and five racial checks, exploring ten enzymatic systems that code for 19 loci. In the first stage large morphological diversity was detected among populations, noticing differentiation of landraces pertaining to the Chalqueño and Cónico races. Regarding the second stage, parameters of genetic diversity indicated 88.0% of polymorphic loci, an average of 2.44 alleles by locus, and expected heterozigosity of 0.209. The population structure showed high degree of differentiation between populations (0.127), with 87.3% of the variation within populations and 12.3% among populations. The joint analysis including both morphological characters and isozymes showed the existence of large diversity between materials, concluding that landraces are in constant evolution and adaptation to the surrounding environment, due to the selection performed by farmers of the region. When exploring phylogenetic relationships between populations using the Neighbor-Joining method with modified Rogers’ distances, it was found that populations from Libres and Mazapiltepec had higher genetic similarity.Tesis (Doctorado en Ciencias, especialista en Genética).- Colegio de Postgraduados, 2010.Consejo Nacional de Ciencia y Tecnología (CONACYT)..

Mots clés : Zea mays L.. Poblaciones nativas. Recursos fitogenéticos. Variabilidad genética. Landraces. Plant genetic resources. Genetic variability.

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