Inheritance of ß-carotene in cassava (Manihot esculenta crantza)

Abstract

A study on the inheritance pattern of beta-carotene in cassava was carried out in the International Institute of Tropical Agriculture (IITA), Ibadan, Nigeria, using four parental lines of cassava, namely two yellow flesh and two white flesh colour genotypes. Crosses of yellow x white and white x yellow were made. The resulting progenies were screened and placed into distinct phenotypic classes and the data obtained were subjected to Chi-square test to determine the goodness of fit to various genetic ratios. The segregation in both crosses fitted into 9:3:3:1 ratio. The quantitative variability of root colour observed in the segregating progenies suggests that two or more genes are involved in the accumulation process. There are no reciprocal differences with respect to the trait studied when the F1 progenies of yellow x white parents were compared with those of the reciprocal cross (white x yellow). This implies that there were no maternal or cytoplasmic effects in the inheritance of the trait. Consequently, either of the genotypes could be used as the female parent in crossing. The appearance of extreme segregation with very high carotene contents beyond the upper limit of yellow flesh parent (deep yellow) in the crosses between 01/1368 x 98/0505 and the reciprocal indicates transgressive segregation, a promise for future recombination strategies. The negative correlation observed between dry matter and flesh colour revealed that the deeper the flesh colours (carotene) the lower the dry matter contents. Key words: Inheritance, vitamin A, beta-carotene, yellow fleshed cassava.