Journal of Taiwan Agricultural Research

Author:Dah-Jing Liao, Pei-Chen Wu, and Dong-Hong Wu*

Abstract:

    Rice blast is one of severe diseases in Taiwan resulting in the loss of grain yield and quality. In this study, novel breeding lines with a single or two blast resistant genes (R gene) were developed by incorporating blast resistance genes (Pia and Piz) from a japonica donor ‘Zenith’ into elite indica cultivar ‘Taichung Sen 17’ (‘TCS17’) based on marker-assisted backcrossing (MABC) strategy. The foreground selection was conducted for the blast resistant genes (Pia and Piz) during the period from BC₁F₁ to BC₃F₂. The background selection, containing 77 InDel and 25 SSR markers, was executed from BC₂F₁ to BC₃F₂ generations. In the first cropping season of 2015, 14 breeding lines with a single or two R genes were selected with a high background recovery rate (> 92%). Based on the results of blast screening trials in 2015 and 2016, breeding lines CNY1042052, CNY1042056 and CNY1042057 with the Pia gene of ‘Zenith’ allele and the Piz gene of ‘TCS17’ allele showed lower severity scale (4, 2 and 1.5, respectively). The sequencing result of both parents in the Piz locus exhibited that ‘TCS17’ has a novel Piz allele. In the yield trial, the grain yield of all novel breeding lines were lower than the recurrent parent ‘TCS17.’ Among 14 lines, the best performance of grain yield was CNY1042052 (5,390 kg ha^-1) and the second highest was CNY1042057 (5,280 kg ha^-1). Based on the evaluation of disease resistance and yield performance, the novel breeding line CNY1042057 possessed the best yield potential and strongest resistance. The correlation analysis between grain yield and yield components of the 14 backcross lines suggested that the limiting factors were panicle number and spikelet fertility. In future, the cultivation strategy (irrigation or fertilizer application) will focus on the control of panicle numbers to increase the grain yield of the novel resistant lines.

Key words:Oryza sativa L., Blast disease, Marker assisted backcross, Disease resistant gene

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