Preliminary study about the inheritance of the carotenoids content in roots from cassava (manihot esculenta crantz) segregating populations

Abstract

Vitamin A deficiency (VA/) is a major problem with huge public health implications. One strategy to overcome this problem is the development of varieties with increased levels of pro-vitamin A carotenoids. Cassava is a relevant crop in many regions of the world where VA/ is prevalent. Significant progress has already been achieved increasing the content of total carotenoids (CTC) in cassava roots. However, little is known about the inheritance of this trait in cassava. In this study the segregations for CTC in several full-sib and self-pollinated (S1) families were analyzed. Parent-offspring regression was used to estimate heritability, which was found into a high level ( and gt;0.60). The analyses of segregations did not allow for the identification of simple Mendelian patterns that could explain the variation in CTC in every family analyzed. However, enough evidence has been generated for a hypothesis that few (2-3) major genes control most of the variation in CTC but their action is modified by fe9 minor genes. Mounting evidence was also found that at least one single dominant gene may inhibit carotenoids accumulation in the roots.Key words: Carotene, cassava roots, genetic variability, inheritance.

La deficiencia de vitamina A es un problema de enormes consecuencias en la salud püblica de muchos países en desarrollo. El perfeccionamiento y difusión de variedades con altos contenidos de carotenoides provitamina A es una estrategia para resolver este problema. La yuca es un cultivo relevante en muchas regiones del mundo cuyos habitantes padecen deficiencia crónica y generalizada de vitamina A. A pesar de que se ha logrado incrementar significativamente el contenido total de carotenoides (CTC) en raices de yuca mediante el mejoramiento genético, es poco lo que se conoce sobre la herencia de CTC. En este estudio se analizaron numerosas familias de hermanos completos y S1 (resultantes de autofecundacio- nes). La heredabilidad, estimada por regresión padre-progenies, resultó ser alta ( and gt; 0.60) y el análisis de las segregaciones no permitió definir patrones de segregación mendeliana simple que explicaran la variación en todas las familias. Sin embargo, hay suficiente evidencia para plantear la hipótesis de que la herencia es relativamente simple y depende de dos o tres genes mayores, cuya expresión es afecta- da por unos pocos genes modificadores menores. Se propone que al menos uno de los genes mayores inhibiría la acumulación de carotenoides.