In a recent study published online in Theoretical and Applied Genetics, Dr. HAN Fangpu's group from the Institute of Genetics and Developmental Biology of the Chinese Academy of Sciences has reported the establishment of new wheat-rye addition lines that conferred resistance to Ug99.
Ug99, a new strain of Puccinia graminis f. sp. Tritici, is virulent to several wheat cultivars worldwide and a significant threat to global food security. Consequently, it is of great significance and urgency to mine new resistance gene sources and transfer them into wheat. Rye, a close relative of wheat, is resistant to leaf rust, stripe rust, stem rust and powdery mildew. It has become a valuable resource of several broad-spectrum disease resistance genes for improvements in wheat genetics.
In this study, the researchers developed two completely new sets wheat-rye disomic addition lines by molecular cytogenetic methods. Subsequently, a new set of telosomic addition lines was obtained from the progenies of wheat-rye monosomic addition lines.
They discovered that the wheat-rye 3RL telosomic addition line carried a novel resistance gene to Ug99 through assessments of disease resistance, cytological analysis, and molecular markers. Therefore, the new Ug99 resistance gene can be used for wheat breeding in the future.
In addition, various chromosomal and centromeric variations are induced by wheat-rye distant hybridization. This process results in ring chromosomes, minichromosomes, dicentric chromosomes, and tricentric chromosomes from the progenies of wheat-rye hybrids.
These materials provide valuable genetic resources for studying the structure, activation/inactivation and function of centromere. These resources will provide important genetic diversity for future wheat-rye hybrid offsprings, as well as clues to the discovery of other Ug99 resistance genes to be introduced into wheat in the future.
This work was supported by the National Science Foundation of China and the Ministry of Science and Technology of China.
The karyotype of wheat-rye addition lines and assessment of resistance to Ug99. (Image by IGDB)