Improving of Rice Blast Resistances in Japonica by Pyramiding Major R Genes

Abstract

Rice blast, caused by the fungal pathogen Magnaporthe oryzae, is a major constraint to rice production worldwide. In this study, we developed monogenic near-isogenic lines (NILs) NILPi9, NILPizt, and NILPi54 carrying genes Pi9, Pizt, and Pi54, respectively, by marker assisted backcross breeding using 07GY31 as the japonica genetic background with good agronomic traits. Polygene pyramid lines (PPLs) PPLPi9+Pi54 combining Pi9 with Pi54, and PPLPizt+Pi54 combining Pizt with Pi54 were 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+Pi54 exhibited higher RF for panicle blast than NILPizt and NILPi54 (P < 0.001), hinting an additive effect on the resistance. However, PPLPi9+Pi54 exhibited lower RF for panicle blast than NILPi9 (P < 0.001), failing to realize an additive effect. PPLPizt+Pi54 showed 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+Pi54 showed higher resistant level and better additive effects on the panicle blast resistance than PPLPi9+Pi54.

Blast resistance gene Pi54 over-expressed in rice to understand its cellular and sub-cellular localization and response to different pathogens

“…However, among the 26-rice blast R genes, Pid2 and pi21 belong to B-lectin receptor kinase and proline containing protein, respectively (Table 1). Pi54 was the third major rice blast R gene to be cloned and functionally studied from indica rice landrace Tetep, and confers broad spectrum resistance for multiple isolates of M. oryzae across different parts of the world 16,17,24,[35][36][37][38] . Recently, the AVR counterpart of Pi54 has also been cloned from the avirulent strain of M. oryzae 39 .…”

“…We found that Pi54 imparts complete resistance against blast pathogen similar to that observed in rice line Tetep, the donor line from which Pi54 gene was originally mapped and cloned [16][17][18]41 . Previously, it has already been reported that pathogen induced expression of Pi54 gene is responsible for wide-ranging resistance against various virulent isolates of blast pathogen from different parts of the world 17,24,[35][36][37][38]42 . Also, Pi54 is responsible for the activation of complex defense response pathways in rice mediated by transcription factors like WRKY6, WRKY45, NAC6 and a battery of defense response genes 18 .…”

Mapping and Deployment of Blast Resistance Gene in Rice – A Work in Progress

“…For bacterial blight, blast, and Brown plant hopper resistance gene Xa4, xa5, Xa21, Pi40 and Bph18 has been introgressed into japonica rice cultivar (Suh et al, 2015). Recently a study was doneon three major blast resistance genes Pi9, Pizt andPi54 to find out the best combination for pyramiding and result showed that combination of Pizt and Pi54 gives higher resistant level and better additive effects on panicle blast resistant than Pi9 and Pi54 combination (Xiao et al, 2017).Some examples of MAS for gene pyramiding in rice are shown in Table 3.…”

Identification of blast resistance QTLs based on two ad vanced backcross populations in rice

“…So far, over 100 blast resistant genes or quantitative trait loci (QTL) have been identified (Su et al 2015;Vasudevan et al 2016;Xiao et al 2017;Zheng et al 2016). Among them, 37 genes have been cloned (Wang et al 2017;Wang et al 2019;Zhao et al 2018), and most of them belong to the 3 nucleotide-binding site (NBS) leucine-rich repeat (LRR) gene family.…”