Browsing by Author "Mariana Ruiz-Rodriguez"

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    Population Genetics, Lethal Yellowing Disease, and Relationships among Mexican and Imported Coconut Ecotypes
    (Crop Science Society of America, 2006-11-21) Daniel Zizumbo-Villarreal; Mariana Ruiz-Rodriguez; Hugh Harries; Patricia Colunga-GarciaMarin
    Lethal Yellowing (LY) is one the main diseases affecting coconut worldwide, making the research for resistant germplasm vital to production. Study objectives were to: (i) estimate diversity and genetic structure within four commercial Mexican ecotypes and five imported ecotypes; (ii) analyze the genetic relationships between Mexican ecotypes and the main coconut gene pools identified worldwide; and (iii) measure the correlation between the genetic distance among these ecotypes and Malayan Yellow Dwarf and their percentage mortality due to LY. The Mexican pool had high genetic diversity ( pl594; HT 5 0.34 6 0.02) similar to that of the populations imported from the world’s main gene pools ( pl 5 94; HT 5 0.36 6 0.01). Both molecular variance and Wright’s index of differentiation indicated strong differentiation among Mexican ecotypes (FST 5 0.32) despite significant gene flow (Nm 5 1.4 to 5.6). UPGMA analysis and exact tests of differentiation suggested that the Indo-African gene pool is found along the Caribbean and Gulf of Mexico coasts, while the Asian- Pacific pool is found on the Pacific coast. High positive correlations were found between genetic distance and LY mortality percentages under severe incidence conditions during 9- and 14-yr periods (r 2 5 0.80; P 5 0.02; r 2 5 0.78; P 5 0.04), suggesting that genetic distance may be useful for the estimation of the potential LY mortality in regions as yet unaffected and identification of potential parents for LY resistance breeding.