Identifying mega-targets for high-yield plant breeding

Promoting genetic diversity in crops is traditional practice for agriculture professionals, and with today's technology, scientists are able to develop breeding programs with great care for the security of crops. This is particularly important due to the numerous risks the world's food supplies face with the changing climate. Genetic diversity in a breeding program is essential as an insurance against unforeseeable changes in the environment and to maintain genetic progress. The incorporation of diversity into a breeding program, however, should be planned carefully. Without taking great care in the incorporation of diversity into a breeding program, poorly adapted genotypes may prevent genetic progress and may therefore have a short-term negative impact on the breeding program. On the other hand, the use of elite genotypes adapted to the local conditions could increase diversity while maintaining genetic gain.

Adapted genotypes can easily be obtained for any environment if the genotypes are evaluated in the target environment. However, it is not possible for a breeding program to evaluate every single candidate genotype. Predicting the performance of a genotype is difficult due to the multiple breeding objectives and the many environmental conditions of genotype evaluation. Therefore, finding adapted elite genotypes is challenging if the genotypes are not evaluated in the targeted environment.

A recent study conducted at Iowa State University proposed data-driven methods to group breeding programs likely to be compatible for germplasm exchange. Specifically, the researchers characterized the genetic diversity of traits in advanced inbred lines of barley from 23 public and private barley breeding programs, which they analyzed to identify mega-targets of selection (i.e. groups of breeding programs likely to be compatible for germplasm exchange) among those breeding programs. Results from this research are published in the January 2009 issue of the journal Crop Science.

The researchers found that all phenotypic traits had significant genetic diversity, but only seven of the 20 traits evaluated showed differences in the amount of diversity among the breeding programs. Some breeding programs had high levels of diversity for most traits, while others had low levels of diversity.

The methodology proposed by the authors groups breeding programs by their performance and by their response to changes in the environment, resulting in sets of breeding programs with similar performance and similar adaptations. They call these sets mega-targets of selection. The authors identified three mega-targets of selection among the barley breeding programs. They hypothesize that exchange of germplasm within mega-targets of selection would produce adapted genotypes with high yields. Research is ongoing to develop larger data sets to evaluate this method.

Source: Crop Science Society of America