Hernán Ceballos, Robert S. Kawuki, Vernon E. Gracen, G. Craig Yencho, Clair H. Hershey
Theoretical and Applied Genetics, July 2015, Publish on line June 21 2015
Abstract
Key message
Consolidates relevant molecular and phenotypic information on cassava to demonstrate relevance of heterosis, and alternatives to exploit it by integrating different tools. Ideas are useful to other asexually reproduced crops.
Abstract
Asexually propagated crops offer the advantage that all genetic effects can be exploited in farmers’ pro-duction fields. However, non-additive effects complicate selection because, while influencing the performance of the materials under evaluation, they cannot be transmit-ted efficiently to the following cycle of selection. Cassava can be used as a model crop for asexually propagated crops because of its diploid nature and the absence of (known) incompatibility effects. New technologies such as genomic selection (GS), use of inbred progenitors based on doubled haploids and induction of flowering can be employed for accelerating genetic gains in cassava. Available informa-tion suggests that heterosis, non-additive genetic effects and within-family variation are relatively large for complex traits such as fresh root yield, moderate for dry matter or starch content in the roots, and low for defensive traits (pest and disease resistance) and plant architecture. The present article considers the potential impact of different technol-ogies for maximizing gains for key traits in cassava, and highlights the advantages of integrating them. Exploiting heterosis would be optimized through the implementation of reciprocal recurrent selection. The advantages of using inbred progenitors would allow shifting the current cassava phenotypic recurrent selection method into line improve-ment, which in turn would allow designing outstanding hybrids rather than finding them by trial and error.
![Conventional breeding, marker assisted selection, genomic selection and inbreeding in clonally propagated crops: a case study for cassava](/Images_upload/images/New Picture (104)(13).png)
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