Rice varieties in all environments require similar basic traits. Especially good grain quality and resistance to diseases, nematodes, and insect pests. Breeding for resistance requires knowledge on resistance mechanisms, genetics, and epidemiology to deploy efficient resistances that reduce crop losses (in yield and quality).
There is an urgent need to broaden the gene pool of rice varieties through the transfer of genes from diverse sources. Advances in tissue culture, molecular markers, and genomics offer new potential to broaden the gene pool of rice by tapping the genetic variability hidden in the wild species and further enhance the efficiency of alien gene introgression. Insect damage reduces yields in rice and causes farmers to use insecticides that are harmful to the environment and human health.
For quantitative traits such as yield, many genes and many environmental factors collectively determine trait performance. Favorable alleles are likely to spread across more than two lines; therefore, requiring the assembly of alleles from different sources in a single inbred line to achieve significant improvement. In recurrent selection (RS), multiple genotypes are crossed and the resulting plants are intercrossed to increase the chance of creating novel allelic combinations.
New genes will be introduced from Oryza species through hybridization and backcrossing in elite parents. The favorable genes or alleles will be tagged with molecular markers for marker-assisted selection. African (O. glaberrima) strains will be used to developed stress-tolerant cultivars and develop new interspecific varieties containing greater and more targeted parts of the African rice genome. This will follow on the successful NERICA varieties in Africa. Wild species of the AA genome will be used to introduce yield-enhancing genes into elite cultivars. Specialized genetic stocks will be developed.
About 100 lines will be identified as potential parents by group discussion (expert view). Genome-wide SSR profiles will also be generated. Parental lines will be selected for the development of ten-parent recurrent selection (RS) populations (high yielding, wide adaptation, physiological trait-oriented, drought-prone lowland, and upland).
The recessive male-sterile gene contained in the IR36 mutant and the dominant male-sterile gene contained in PXDMS will each be transferred into five parental lines. This is to increase the genetic potential of and genetic diversity among the male-sterile lines to be used in future recurrent selection (RS).
Computer simulation experiments will be designed to investigate the effects of key factors on RS efficiencies such as heritability, crossing schemes including male-sterility-facilitated and manual crossing, selection intensity, etc. The results of these simulations will then be used to design more efficient RS schemes.