Cassava Mutation Breeding: Current Status and Trends

摘要

Cassava (Manihot esculenta Crantz) is an important energy source in the diets of millions of people in the tropical and subtropical regions of the world, especially the poor. Also its industrial uses are steadily growing for starch, animal feed and bio-ethanol. Although it has high economic and social relevance, few major scientific efforts have been made to improve the crop until the 1970s. With the goals and objectives of cassava improvement through breeding, different strategies have been developed during the last several decades, such as evaluation and selection of the local landraces, introduced germplasm (as clones or segregating Fl population), hybridization (including inbreeding by both recurrent back-cross schemes and double haploids (DH)), interspecific hybridization, polyploidy breeding, genetic transformation, use of molecular markers and mutation breeding. Induced mutation breeding on cassava has been explored in the last several decades with few published papers. Yet, the production of novel genotypes, such as high am-ylose and small granule mutants and mutants with tolerance to post harvest physiological deterioration (PPD), has been reported. These results suggest that mutagenesis could be an effective alternative for cassava breeding. However, many drawbacks still exist in cassava mutation breeding, such as the occurrence of chimeras. Validated and developing protocols for different biotechnologies, such as TILLING protocol, cassava genome sequencing and cassava somatic embryogenesis, will significantly ameliorate the drawbacks to traditional mutation breeding, and consequently aid the routine application of induced mutation in both cassava improvement and in gene discovery and elucidation.