Abstract:

Rice blast is one of the most widespread and devastating diseases worldwide. Pyramiding more rice blast resistance gene into one rice variety is economic and effective approach for improvement of rice variety with durable resistance to blast. It can slow the directional evolution of Magnaporthe grisea and prolong the service life of resistance variety. In this study, three F6 recombinant inbred populations were made using Lijiangxintuanheigu (LTH) near-isogenic lines (NILs) as parents. By means of resistance test with differential isolates, five pyramid lines carrying two resistance genes were obtained: 1) F-Kpib-3 and F-Kpib-6 for resistance genes Pi-kp/Pi-b; 2) F-Kita2-7 and F-Kita2-9 for Pi-k/Pi-ta² and 3) F-Kmita for Pi-km/Pi-ta. The lines with the same gene combination had the same resistance reactions and higher resistance frequencies than the LTH NILs. The resistance frequencies were 100.0%, 91.7% and 50.0% for the above three groups, respectively. And also their disease scores were lower than the LTH NILs’. This implies that gene pyramiding could increase the spectrum and the strength of resistance to blast pathogen. The pyramiding genes are a simply additive relationship. The pyramid lines with LTH background may be used for identifying pathogenic types and monitoring variation directions of M. grisea in the field and used as resistant parents for blast resistance breeding of rice.

Key words: LTH, Near-isogenic line, Pyramid line, Blast resistance