Journal of Taiwan Agricultural Research

Author:Dah-Jing Liao, Lung-Che Chen, Chih-Wen Wu, and Chia-Lin Chung*

Abstract:

    Two sets of rice blast differential lines introduced from IRRI, ‘LTH’ monogenic lines (MLs) and ‘CO 39’ near isogenic lines (NILs), were tested for response to rice leaf blast at the upland blast nursery at Chiayi Agricultural Experiment Branch, Taiwan Agricultural Research Institute for 5 cropping seasons during 2011–2014. The results showed that 37.5% of the ‘LTH’ MLs and 71.4% of the ‘CO 39’ NILs exhibited moderate to high resistance (disease severity ≤ 4). In particular, Piz-5 [in IRBLz5-CA and IRBLz5-CA(R)], Pib (in IRBLb-B), Pi12(t) (in IRBL12-M), and Pita2 (in IRBLta2-Pi) consistently showed high resistance, indicating that the four resistance genes might be incompatible with most of the Magnaporthe oryzae races in the nursery, therefore their resistance is likely to be more broad-spectrum. It was observed that some resistance genes had different reactions in the ‘LTH’ and ‘CO 39’ genetic backgrounds. For instance, Pik (from ‘Kanto 51’) and Pik-p (from ‘K60’) were moderately resistant in ‘CO 39’ background but highly susceptible in ‘LTH’ background, suggesting that their resistance may be more effective in the Indica background or the background containing other resistance gene(s). Pik-h (from ‘K3’) and Pi1 (from ‘C101LAC’) conferred stronger resistance in ‘LTH’ background (reduction of 3–4 scales on severity) than in ‘CO 39’ background (reduction of 1 scale on severity), which may be due to the mask effect contributed from the resistance of Pia and Pi-CO39(t) in ‘CO 39’. Because of the potential interference of mask effect in ‘CO 39’, the ‘LTH’ MLs can be a better differential system for the identification of effective R genes in Taiwan. It was also found that some differential lines and their donor parents reacted differently to blast, possibly due to the genetic background effects and/or the accumulative effects of multiple R genes in the genomes. ‘BL1’ and ‘Toride 1’, the donor lines carrying more than one R genes, showed higher resistance than their corresponding ‘LTH’ and ‘CO 39’ differential lines.

Key words:Magnaporthe oryzae, Blast nursery, Differential lines, Resistance genes

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