title: Biological Implications in Cassava for the Production of Amylose-Free Starch: Impact on Root Yield and Related Traits.
abstract: Cassava (Manihot esculenta, Crantz) is an important food security crop, but it is becoming an important raw material for different industrial applications. Cassava is the second most important source of starch worldwide. Novel starch properties are of interest to the starch industry, and one them is the recently identified amylose-free (waxy) cassava starch. Waxy mutants have been found in different crops and have been often associated with a yield penalty. There are ongoing efforts to develop commercial cassava varieties with amylose-free starch. However, little information is available regarding the biological and agronomic implications of starch mutations in cassava, nor in other root and tuber crops. In this study, siblings from eight full-sib families, segregating for the waxy trait, were used to determine if the mutation has implications for yield, dry matter content (DMC) and harvest index in cassava. A total of 87 waxy and 87 wild-type starch genotypes from the eight families were used in the study. The only significant effect of starch type was on DMC (p < 0.01), with waxy clones having a 0.8% lower content than their wild type counterparts. There was no effect of starch type on fresh root yield (FRY), adjusted FRY and harvest index. It is not clear if lower DMC is a pleiotropic effect of the waxy starch mutation or else the result of linked genes introgressed along with the mutation. It is expected that commercial waxy cassava varieties will have competitive FRYs but special efforts will be required to attain adequate DMCs. This study contributes to the limited knowledge available of the impact of starch mutations on the agronomic performance of root and tuber crops.
authors.affiliation: Department of Plant Breeding, Swedish University of Agricultural Sciences, AlnarpSweden; Centro Internacional de Agricultura Tropical, PalmiraColombia.
authors.forename: Amanda
authors.initials: A
authors.lastname: Karlström
authors.affiliation: Centro Internacional de Agricultura Tropical, Palmira Colombia.
authors.forename: Fernando
authors.initials: F
authors.lastname: Calle
authors.affiliation: Centro Internacional de Agricultura Tropical, Palmira Colombia.
authors.forename: Sandra
authors.initials: S
authors.lastname: Salazar
authors.affiliation: Centro Internacional de Agricultura Tropical, Palmira Colombia.
authors.forename: Nelson
authors.initials: N
authors.lastname: Morante
authors.affiliation: Centro Internacional de Agricultura Tropical, PalmiraColombia; Centre de Coopération Internationale en Recherche Agronomique pour le Développement, UMR Qualisud, MontpellierFrance.
authors.forename: Dominique
authors.initials: D
authors.lastname: Dufour
authors.affiliation: Centro Internacional de Agricultura Tropical, Palmira Colombia.
authors.forename: Hernán
authors.initials: H
authors.lastname: Ceballos
keywords: cassava markets; economic impact; root and tuber crops; waxy starch; yield penalty