title: Improving of Rice Blast Resistances inJaponicaby Pyramiding Major R Genes.
abstract: Rice blast, caused by the fungal pathogenMagnaporthe oryzae, is a major constraint to rice production worldwide. In this study, we developed monogenic near-isogenic lines (NILs) NILPi9, NILPizt, and NILPi54carrying genesPi9,Pizt, andPi54, respectively, by marker assisted backcross breeding using 07GY31 as thejaponicagenetic background with good agronomic traits. Polygene pyramid lines (PPLs) PPLPi9+Pi54combiningPi9withPi54, and PPLPizt+Pi54combiningPiztwithPi54were then developed using corresponding NILs with genetic background recovery rates of more than 97%. Compared to 07GY31, the above NILs and PPLs exhibited significantly enhanced resistance frequencies (RFs) for both leaf and panicle blasts. RFs of both PPLs for leaf blast were somewhat higher than those of their own parental NILs, respectively, and PPLPizt+Pi54exhibited higher RF for panicle blast than NILPiztand NILPi54(P< 0.001), hinting an additive effect on the resistance. However, PPLPi9+Pi54exhibited lower RF for panicle blast than NILPi9(P< 0.001), failing to realize an additive effect. PPLPizt+Pi54showed higher resistant level for panicle blast and better additive effects on the resistance than PPLPi9+Pi54. It was suggested that major R genes interacted with each other in a way more complex than additive effect in determining panicle blast resistance levels. Genotyping by sequencing analysis and extreme-phenotype genome-wide association study further confirmed the above results. Moreover, data showed that pyramiding multiple resistance genes did not affect the performance of basic agronomic traits. So the way to enhance levels of leaf and panicle blast resistances for rice breeding in this study is effective and may serve as a reference for breeders.Key Message:Resistant levels of rice blast is resulted from different combinations of major R genes, PPLPizt+Pi54showed higher resistant level and better additive effects on the panicle blast resistance than PPLPi9+Pi54.
authors.affiliation: Lixiahe Agricultural Research Institute of Jiangsu Province, Yangzhou - Jiangsu Collaborative Innovation Center for Modern Crop Production, Nanjing - Institute of Jiangsu Province National Rice Industry Technology System of Yangzhou Comprehensive Experimental Station Yangzhou, China.
authors.forename: Ning
authors.initials: N
authors.lastname: Xiao
authors.affiliation: Lixiahe Agricultural Research Institute of Jiangsu Province, Yangzhou - Jiangsu Collaborative Innovation Center for Modern Crop Production, Nanjing - Institute of Jiangsu Province National Rice Industry Technology System of Yangzhou Comprehensive Experimental Station Yangzhou, China.
authors.forename: Yunyu
authors.initials: Y
authors.lastname: Wu
authors.affiliation: Lixiahe Agricultural Research Institute of Jiangsu Province, Yangzhou - Jiangsu Collaborative Innovation Center for Modern Crop Production, Nanjing - Institute of Jiangsu Province National Rice Industry Technology System of Yangzhou Comprehensive Experimental Station Yangzhou, China.
authors.forename: Cunhong
authors.initials: C
authors.lastname: Pan
authors.affiliation: Lixiahe Agricultural Research Institute of Jiangsu Province, Yangzhou - Jiangsu Collaborative Innovation Center for Modern Crop Production, Nanjing - Institute of Jiangsu Province National Rice Industry Technology System of Yangzhou Comprehensive Experimental Station Yangzhou, China.
authors.forename: Ling
authors.initials: L
authors.lastname: Yu
authors.affiliation: Lixiahe Agricultural Research Institute of Jiangsu Province, Yangzhou - Jiangsu Collaborative Innovation Center for Modern Crop Production, Nanjing - Institute of Jiangsu Province National Rice Industry Technology System of Yangzhou Comprehensive Experimental Station Yangzhou, China.
authors.forename: Yu
authors.initials: Y
authors.lastname: Chen
authors.affiliation: Lixiahe Agricultural Research Institute of Jiangsu Province, Yangzhou - Jiangsu Collaborative Innovation Center for Modern Crop Production, Nanjing - Institute of Jiangsu Province National Rice Industry Technology System of Yangzhou Comprehensive Experimental Station Yangzhou, China.
authors.forename: Guangqing
authors.initials: G
authors.lastname: Liu
authors.affiliation: Lixiahe Agricultural Research Institute of Jiangsu Province, Yangzhou - Jiangsu Collaborative Innovation Center for Modern Crop Production, Nanjing - Institute of Jiangsu Province National Rice Industry Technology System of Yangzhou Comprehensive Experimental Station Yangzhou, China.
authors.forename: Yuhong
authors.initials: Y
authors.lastname: Li
authors.affiliation: Lixiahe Agricultural Research Institute of Jiangsu Province, Yangzhou - Jiangsu Collaborative Innovation Center for Modern Crop Production, Nanjing - Institute of Jiangsu Province National Rice Industry Technology System of Yangzhou Comprehensive Experimental Station Yangzhou, China.
authors.forename: Xiaoxiang
authors.initials: X
authors.lastname: Zhang
authors.affiliation: Lixiahe Agricultural Research Institute of Jiangsu Province, Yangzhou - Jiangsu Collaborative Innovation Center for Modern Crop Production, Nanjing - Institute of Jiangsu Province National Rice Industry Technology System of Yangzhou Comprehensive Experimental Station Yangzhou, China.
authors.forename: Zhiping
authors.initials: Z
authors.lastname: Wang
authors.affiliation: Lixiahe Agricultural Research Institute of Jiangsu Province, Yangzhou - Jiangsu Collaborative Innovation Center for Modern Crop Production, Nanjing - Institute of Jiangsu Province National Rice Industry Technology System of Yangzhou Comprehensive Experimental Station Yangzhou, China.
authors.forename: Zhengyuan
authors.initials: Z
authors.lastname: Dai
authors.affiliation: Institute of Genetics and Developmental Biology, Chinese Academy of Sciences Beijing, China.
authors.forename: Chengzhi
authors.initials: C
authors.lastname: Liang
authors.affiliation: Lixiahe Agricultural Research Institute of Jiangsu Province, Yangzhou - Jiangsu Collaborative Innovation Center for Modern Crop Production, Nanjing - Institute of Jiangsu Province National Rice Industry Technology System of Yangzhou Comprehensive Experimental Station Yangzhou, China.
authors.forename: Aihong
authors.initials: A
authors.lastname: Li
keywords: Japonica rice; blast resistance; polygene pyramid lines