Introgression of Stem Rust Resistance into Popular Kenyan Wheat Varieties to Improve Production

Aim: The objective of this study was to assess the introgression of the stem rust resistance genes into the BC1F1 plants using molecular markers.

Place and Duration of Study: Field experiments were carried out in a nursery, at Kenya Agricultural and Livestock Research Organization (KALRO) Njoro Centre, Nakuru, Kenya at 0.3ºS and 35.9ºE and 2185 m above sea level from June 2012 to December 2013. Laboratory work was carried out in the Biotechnology laboratory, KALRO Njoro.

Methodology: Polymerase Chain Reaction (PCR) amplifications were carried out to assess the introgression of stem rust resistance genes into the BC1F1 plants. Analysis of genetic variation was done at each locus in terms of the number of alleles observed, heterozygosity, expected heterozygosity, Shannon's diversity index, genetic diversity and gene frequency using genetic analysis package POPGENE Version 1.32. The neighbouring joining method was used to construct a dendrogram from a distance matrix based on Sokal and Michener’s genetic distances, using MEGA4 software 1in Power Marker 3.25.

Results: Amplification using PCR showed that wheat BC1F1 plants accessions NP3, NP12, NP89, NP163, NP192 and Kingbird were positive for the Lr34 gene while the susceptible plants and Njoro Bw2 were negative. Evaluation done on three molecular markers showed that CSLV34 was polymorphic across the BC1F1 plant accessions with a total of 2 alleles per locus. The 17 wheat BC1F1 plant accessions and their parents (Njoro Bw2 and Kingbird) were placed into 2 clusters using the markers as a result of introgression, considering that the clustering in this study was purposively based on the presence or absence of the resistance genes. This indicates that the Lr34 gene which is an APR gene was successfully introgressed into five BC1F1 accession plants (NP3, NP12, NP89, NP163 and NP192).

Conclusion: The resistant BC1F1 accession plants (NP3, NP12, NP89, NP163 and NP192) showed success in the introgression of the Lr34 gene that gives resistance to stem rust at adult plant stage together with other minor genes including Sr2 and Lr46. These can further be developed in the field, multiplied and the seeds distributed to the farmers as they showed low disease severity to stem rust disease.