Molecular profiling of blast resistance genes and evaluation of leaf and neck blast disease reaction in rice

The completion of the genome sequences of both rice and Magnaporthe oryzae has strengthened the position of rice blast disease as a model to study plant–pathogen interactions in monocotyledons. Genetic studies of blast resistance in rice were established in Japan as early as 1917. Despite such long-term study, examples of cultivars with durable resistance are rare, partly due to our limited knowledge of resistance mechanisms. A rising number of blast resistance genes and quantitative trait loci (QTL) have been genetically described, and some have been characterized during the last 20 years. Using the rice genome sequence, can we now go a step further toward a better understanding of the genetics of blast resistance by combining all these results? Is such knowledge appropriate and sufficient to improve breeding for durable resistance? A review of bibliographic references identified 85 blast resistance genes and approximately 350 QTL, which we mapped on the rice genome. These data provide a useful update on blast resistance genes as well as new insights to help formulate hypotheses about the molecular function of blast QTL, with special emphasis on QTL for partial resistance. All these data are available from the OrygenesDB database.

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Rice Blast Disease in India: Present Status and Future Challenges

10.5772/intechopen.98847 ◽

2021 ◽

Author(s):

Deepak Chikkaballi Annegowda ◽

Mothukapalli Krishnareddy Prasannakumar ◽

Hirehally Basavarajegowda Mahesh ◽

Chethana Bangera Siddabasappa ◽

Pramesh Devanna ◽

...

Keyword(s):

Resistance Genes ◽

Oryza Sativa L ◽

Blast Resistance ◽

Gene Pyramiding ◽

Climatic Conditions ◽

Blast Disease ◽

Selection Marker ◽

Rice Varieties ◽

Future Challenges ◽

Blast Resistance Genes

Rice (Oryza sativa L.) is the staple food of the majority of Indians, and India is both the major producer and consumer of rice. Rice cultivation in India is confronted with diverse agro-climatic conditions, varying soil types, and several biotic and abiotic constraints. Among major fungal diseases of Rice in India, the blast caused by Magnaporthe oryzae is the most devastating disease, with the neck blast being the most destructive form. Most of the blast epidemic areas in India have been identified with a mixture of races blast fungus resulting in the resistance breakdown in a short period. At present, a more significant number of the rice varieties cultivated in India were bred by conventional breeding methods with blast resistance conferred by a single resistance gene. Therefore, the blast disease in India is predominantly addressed by the use of ecologically toxic fungicides. In line with the rest of the world, the Indian scientific community has proven its role by identifying several blast resistance genes and successfully pyramiding multiple blast resistance genes. Despite the wealth of information on resistance genes and the availability of biotechnology tools, not a great number of rice varieties in India harbor multiple resistance genes. In the recent past, a shift in the management of blast disease in India has been witnessed with a greater focus on basic research and modern breeding tools such as marker-assisted selection, marker-assisted backcross breeding, and gene pyramiding.

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Mapping Blast Resistance Genes in Rice Varieties ‘Minghui 63’ and ‘M-202’

Plant Disease ◽

10.1094/pdis-09-21-2095-re ◽

2021 ◽

Author(s):

Yulin Jia ◽

Melissa H Jia ◽

Zongbu Yan

Keyword(s):

Resistance Genes ◽

Blast Resistance ◽

Interval Mapping ◽

Blast Disease ◽

Chromosome 1 ◽

Rice Breeding ◽

Resistance Qtls ◽

Rice Varieties ◽

Short Period ◽

Blast Resistance Genes

Rice blast disease caused by the fungus Magnaporthe oryzae (syn. M. grisea) is one of the most lethal diseases for sustainable rice production worldwide. Blast resistance mediated by major resistance genes are often broken-down after a short period of deployment, while minor blast resistance genes, each providing a small effect on disease reactions, are more durable. In the present study, we first evaluated disease reactions of two rice breeding parents ‘Minghui 63’ and ‘M-202’ with 11 US blast races, IA45, IB1, IB45, IB49, IB54, IC1, IC17, ID1, IE1, IG1, and IH1 commonly found under greenhouse conditions using a category disease rating resembling infection types under field conditions. ‘Minghui 63’ exhibited differential resistance responses in comparison with that of ‘M-202’ to the tested blast races. A recombinant inbred line (RIL) population of 275 lines from a cross between ‘Minghui 63’ and ‘M-202’ was also evaluated with the above mentioned blast races. The population was genotyped with 156 simple sequence repeat (SSR) and insertion and deletion (Indel) markers. A linkage map with a genetic distance of 1022.84 cM was constructed using inclusive composite interval mapping (ICIM) software. A total of 10 resistance QTLs, eight from ‘Minghui 63’ and two from ‘M-202’, were identified. One major QTL, qBLAST2 on chr 2, was identified by seven races/isolates. The remaining nine minor resistance QTLs were mapped on chromosome 1, 3, 6, 9, 10, 11 and 12. These findings provide useful genetic markers and resources to tag minor blast resistance genes for marker assisted selection in rice breeding program and for further studies of underlying genes.

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Selection of Differential Isolates of Magnaporthe oryzae for Postulation of Blast Resistance Genes

Phytopathology ◽

10.1094/phyto-09-17-0333-r ◽

2018 ◽

Vol 108 (7) ◽

pp. 878-884 ◽

Cited By ~ 3

Author(s):

W. W. Fang ◽

C. C. Liu ◽

H. W. Zhang ◽

H. Xu ◽

S. Zhou ◽

...

Keyword(s):

Resistance Genes ◽

Magnaporthe Oryzae ◽

Blast Resistance ◽

Polymerase Chain Reaction Analysis ◽

Colony Growth ◽

Blast Disease ◽

Avirulence Genes ◽

Rice Varieties ◽

Minimum Number ◽

Blast Resistance Genes

A set of differential isolates of Magnaporthe oryzae is needed for the postulation of blast resistance genes in numerous rice varieties and breeding materials. In this study, the pathotypes of 1,377 M. oryzae isolates from different regions of China were determined by inoculating detached rice leaves of 24 monogenic lines. Among them, 25 isolates were selected as differential isolates based on the following characteristics: they had distinct responses on the monogenic lines, contained the minimum number of avirulence genes, were stable in pathogenicity and conidiation during consecutive culture, were consistent colony growth rate, and, together, could differentiate combinations of the 24 major blast resistance genes. Seedlings of rice cultivars were inoculated with this differential set of isolates to postulate whether they contain 1 or more than 1 of the 24 blast resistance genes. The results were consistent with those from polymerase chain reaction analysis of target resistance genes. Establishment of a standard set of differential isolates will facilitate breeding for blast resistance and improved management of rice blast disease.

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Effects of Pyramiding Quantitative Resistance Genes pi21, Pi34, and Pi35 on Rice Leaf Blast Disease

Plant Disease ◽

10.1094/pdis-02-14-0214-re ◽

2015 ◽

Vol 99 (7) ◽

pp. 904-909 ◽

Cited By ~ 26

Author(s):

Nobuko Yasuda ◽

Takayuki Mitsunaga ◽

Keiko Hayashi ◽

Shinzo Koizumi ◽

Yoshikatsu Fujita

Keyword(s):

Resistance Genes ◽

Blast Resistance ◽

Quantitative Resistance ◽

Durable Resistance ◽

Rice Cultivar ◽

Infection Process ◽

Blast Disease ◽

Leaf Blast ◽

Gene Combination ◽

Blast Resistance Genes

Development of resistant cultivars has been an effective method for controlling rice blast disease caused by Magnaporthe oryzae. Quantitative blast resistance genes may offer durable resistance because the selection pressure on M. oryzae to overcome resistance is low as a result of the genes’ moderate susceptibility. Because the effects of individual resistance genes are relatively small, pyramiding these genes in rice cultivars is a promising strategy. Here, we used near-isogenic and backcross lines of rice cultivar Koshihikari with single- or two-gene combinations of blast resistance genes (pi21, Pi34, and Pi35) to evaluate the suppression of leaf blast. The severity of the disease was assessed throughout the infection process. Resistance varied among the lines: Pi35 conferred the strongest resistance, while Pi34 showed the weakest effects. Two types of combined-gene interactions were observed, and they varied on the basis of gene combination and characteristic of the infection: (i) the combination of two resistance genes was more effective than either of the genes individually or (ii) the combination of two resistance genes was similar to the level of the most effective resistance gene in the pair. The most effective gene combination for the suppression of leaf blast was pi21 + Pi35.

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