Rice production in irrigated areas of Thailand has been frequently and strongly affected by abiotic stresses resulting from unfavorable climatic changes, such as flooding and drought, as well as by biotic stresses caused by bacterial leaf blight (BB), leaf/neck blast (BL) and brown planthopper (BPH). Therefore, new successful breeding lines must possess multiple types of resistance to both biotic and abiotic stresses, as well as demonstrating specific grain qualities and high yield. However, pyramiding multiple genes into a desirable genetic background can take years to accomplish.
To shorten the time, researchers redesigned the gene-pyramiding platform by integrating marker assisted selection into pseudo-backcross breeding. With this platform, they were successful in pyramiding five functional genes (xa5, Xa21, Sub1A-C, SSIIa, TPS) and three QTLs (qBph3, qBL1, qBL11) into the ‘PinK3’ genome background within only seven breeding cycles in four years. ‘PinK3’ is an aromatic, high-yielding, non-photoperiod-sensitive, high-amylose rice variety, but it is susceptible to BPH, BB, BL and Sub stresses. The new, improved lines have a high-yield phenotype that confers submergence tolerance and resistance to BPH, BB and BL. This is the first report describing the application of pseudo-backcrossing to significantly shorten the time required for gene/QTL pyramiding in an annual crop (rice).
This work was led by Dr. Apichart Vanavichit, in collaboration with researchers from Rice Gene Discovery Laboratory and Kasetsart University.