Gene action and heterosis in F1 clonal progenies of cassava for β-Carotene and farmers’ preferred traits

Nduwumuremyi Athanase,Melis Rob

doi:10.1016/j.heliyon.2019.e01807

Abstract

Gene action and heterosis provides information to assist breeder for selecting and generating improved plant recombinants. This study aimed at determining the gene action of selected cassava traits. The F1 clones exhibited considerable phenotypic variability between families and offsprings. The best F1 progenies had a higher amount of β-carotene (β-C) of 6.12 mg 100 g−1 against 1.32 mg 100 g−1 of the best parent. This superiority could be attributed to the over-dominance from the recombination of additive gene action and epistasis. The general combining ability (GCA) of parents and specific combining ability (SCA) of combinations were significant for different traits, and indicating the role of additive and non-additive gene action in controlling such traits. The significant GCA for β-C and postharvest physiological deterioration (PPD) indicates the role of additive gene action. The significant SCA for cassava mosaic disease (CMD) and cassava brown streak disease (CBSD) showed a predominance of non-additive gene action. The F1 progenies from the family Mavoka x Garukunsubire expressed the highest positive heterosis for CMD, dry matter and β-C. The high positive heterosis for β-C and DMC could be linked to transgressive segregation, because one of the parents was poor combiner.

Highlights

Cassava is a cash crop and generates income for smallholder farmers in many countries of tropical and subtropical Africa, Asia, and Latin America
The selected cassava traits evaluated in this study, showed a considerable variation among the F1 clones of fifteen families generated through 6 Â 6 half-diallel mating design
Some F1 progenies had higher amounts of β-C and higher post-harvest physiological deterioration (PPD) tolerance than their parents, which could be attributed to the transgressive segregation and heterosis, which are desirable for the improvement of most cassava traits

Summary

Introduction

Cassava is a cash crop and generates income for smallholder farmers in many countries of tropical and subtropical Africa, Asia, and Latin America. The viral diseases and postharvest losses are the most serious challenges for cassava production in developing countries. Cassava breeding is the most sustainable strategy to generate new high yielding recombinants that are resistant to diseases, with delayed physiological deterioration. Information generated on the combining ability and heterosis assists in the development of new improved recombinants (Mendes et al, 2015; Zhao et al, 2016). There is limited genetic information on the combining ability and heterosis for yield, postharvest and quality, disease traits, and other important cassava traits in Rwanda

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