Breeding of a near-isogenic wheat line resistant to wheat blast at both seedling and heading stages through incorporation ofRmg8

Abstract

AbstractWheat blast caused byPyricularia oryzae Triticumpathotype (MoT) has been transmitted from South America to Bangladesh and Zambia and is now spreading in these countries. To prepare against its further spread to Asian countries, we introducedRmg8, a gene for resistance to wheat blast, into a Japanese elite cultivar, Chikugoizumi (ChI), through recurrent backcrosses, and established ChI near-isogenic lines, #2-1-10 with theRmg8/Rmg8genotype and #4-2-10 with thermg8/rmg8genotype. A molecular analysis suggested that at least 96.6% of the #2-1-10 genome was derived from the recurrent parent ChI. The #2-1-10 line was resistant to MoT not only in primary leaves at the seedling stage but also in spikes and flag leaves at the heading stage. The strength of the resistance in spikes of thisRmg8carrier was comparable to that of a carrier of the 2NS segment which has been the only one genetic resource released to farmer’s field for wheat blast resistance. On the other hand, the 2NS resistance was not expressed on leaves at the seedling stage nor flag leaves at the heading stage. Considering that leaf blast has been increasingly reported and regarded as an important inoculum source for spike blast,Rmg8expressed at both the seedling and heading stages, or more strictly in both leaves and spikes, is suggested to be useful to prevent the spread of MoT in Asia and Africa.