Nature_biotechlology_Wanjianmin_nbt.3069

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A gene cluster encoding lectin receptor kinases confers broad-spectrum and durable insect resistance in rice

Yuqiang Liu1,3, Han Wu1,3, Hong Chen1, Yanling Liu1, Jun He1, Haiyan Kang1, Zhiguang Sun1, Gen Pan1, Qi Wang1, Jinlong Hu1, Feng Zhou1, Kunneng Zhou1, Xiaoming Zheng2, Yulong Ren1, Liangming Chen1, Yihua Wang1, Zhigang Zhao1, Qibing Lin2, Fuqing Wu2, Xin Zhang2, Xiuping Guo2, Xianian Cheng1, Ling Jiang1, Chuanyin Wu2, Haiyang Wang2 & Jianmin Wan1,2

©2014 Nature America, Inc. All rights reserved.

The brown planthopper (BPH) is the most destructive pest of rice (Oryza sativa) and a substantial threat to rice production, causing losses of billions of dollars annually1,2. Breeding of resistant cultivars is currently hampered by the rapid breakdown of BPH resistance2. Thus, there is an urgent need to identify more effective BPH-resistance genes. Here, we report molecular cloning and characterization of Bph3, a locus in rice identified more than 30 years ago that confers resistance to BPH. We show that Bph3 is a cluster of three genes encoding plasma membrane–localized lectin receptor kinases (OsLecRK1-OsLecRK3). Introgression of Bph3 into susceptible rice varieties by transgenic or marker-assisted selection strategies significantly enhanced resistance to both the BPH and the white back planthopper. Our results suggest that these lectin receptor kinase genes function together to confer broad-spectrum and durable insect resistance and provide a resource for molecular breeding of insect-resistant rice cultivars.

BPH (Nilaparvata lugens Stål, Hemiptera, Delphacidae) is a monopha-gous, phloem-sucking herbivore. It sucks the sap from the rice phloem using its stylet, and causes direct damage to rice plants. BPH can also cause indirect damage to rice plants through the transmission of viruses including the rice ragged stunt virus and grassy stunt virus2. Repeated overapplication of pesticides for BPH management has heavily polluted the environment3. Breeding of resistant cultivars is the most cost-effective and environmentally responsible strategy for BPH management but developing insect resistant cultivars by traditional breeding approaches is extremely difficult and time consuming owing to a paucity of knowledge about BPH resistance genes and germplasm.

To date, 28 BPH resistance loci have been identified from cultivated and wild species of Oryza2,4,5. Only two of these resistance genes, Bph14 and Bph26 have been cloned to date6,7. In addition, BPH resist-ance of IR26 and IR36, two widely cultivated rice varieties that harbor the BPH resistance loci Bph1 and bph2, respectively, was quickly

broken down in just a few years owing to the rapid adaptation of the BPH8. Thus, there is still an urgent need to identify new types of resistance genes and germplasm for developing efficient approaches to breed broad-spectrum and durable BPH-resistant rice cultivars. Notably, the Bph3 locus, originally identified in the Sri Lankan indica cultivar Rathu Heenati9, displayed resistance to four BPH bio-types (BPH biotypes refer to specific populations of BPH classified according to their virulence on different BPH resistance genes)2,10. Furthermore, rice varieties harboring Bph3 deployed more than

830 years ago in the Philippines are still resistant to BPH. However,

the molecular basis of this broad-spectrum and durable resistance of Bph3 against BPH remains unknown.

We observed that Bph3-containing Rathu Heenati infested with BPH of mixed biotypes (biotype 2 being the dominant one) collected from a field in Nanjing were not visibly damaged, whereas BPH infes-tation caused 100% mortality in the susceptible japonica cultivar 02428 (Fig. 1a,b) and indica cultivar Taichung Native 1 (Supplementary Fig. 1a,b). In addition, fewer BPHs were found on Rathu Heenati than on 02428 and Taichung Native 1 in a feeding preference experi-ment (Fig. 1c,e and Supplementary Fig. 1c). When infested with a fixed number of BPHs on Rathu Heenati, 02428 and Taichung Native 1 seedlings in enclosed cages, the BPH population on 02428 and Taichung Native 1 increased steadily over time. In contrast, the BPH population on Rathu Heenati decreased dramatically within a few hours of infestation (Fig. 1e and Supplementary Fig. 1d). In addition, both the honeydew excreted by BPH and the BPH survival rate on Rathu Heenati in a no-choice feeding test were much lower than those on 02428 and Taichung Native 1 (Fig. 1f,g and Supplementary Fig. 1e,f). The reduced amount of honeydew excretion from BPH on Rathu Heenati is consistent with the previous finding that BPH is less effective in ingesting sieve sap on Rathu Heenati based on an electrical penetration graphs (EPGs) study11. Collectively, these observations indicate that Rathu Heenati displays a strong resistance to BPH prob-ably through interfering with BPH feeding.

Bph3 was previously mapped to the short arm of chromosome 4 (refs. 12,13). Using 6,514 BC2F2:3 and 13,256 BC3F2:3 lines derived

Nanjing, China. 2National Key Facility for Crop Gene Resources and Genetic Improvement, Institute of Crop Science, Chinese Academy of Agricultural Sciences, Beijing, China. 3These authors contributed equally to this work. Correspondence and requests for materials should be addressed to J.W. (wanjm@njau.edu.cn or wanjianmin@caas.cn).

Received 7 September 2013; accepted 15 October 2014; published online 8 December 2014; doi:10.1038/nbt.3069

1National Key Laboratory for Crop Genetics and Germplasm Enhancement, Jiangsu Plant Gene Engineering Research Center, Nanjing Agricultural University,

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