Selected rice varieties with different resistant resources to blast in China.
Hybrid rice has demonstrated promises of yield gain for over several decades since its conception and massive deployment in China. One of the common bottlenecks of hybrid rice is the availability of suitable breeding lines as parents to produce marketable rice grains. Due to limitation of genetic diversity of breeding parent, hybrid rice is extremely vulnerable to rice blast disease caused by the fungal pathogen Magnaporthe oryzae. M. oryzae is a highly adaptive fungus that often gains new virulence to reduce crop resistance resulting in massive yield loss and crop failure. To secure yield gain of hybrid rice, identification and integration of diverse sources of resistance genes into hybrid rice are super critical. In this chapter, we will present strategies to identify, characterize, and stack effective blast resistance genes in hybrid rice breeding in China.
- rice blast
- resistance gene
- hybrid rice
In China, the research on hybrid rice has gone on for more than 50 years. Professor Yuan first found the male sterility in 1964 and started hybrid rice research in China and, subsequently, creatively proposed the three-line, two-line, and one-line breeding conception . Three-line hybrid rice was defined as restorer line, cytoplasmic male sterile line, and maintainer line; two-line hybrid rice was defined as restorer line and photo-thermosensitive genic male sterile; one-line hybrid rice was defined to maintain the heterosis by diploid line through apomixes . Until now, hybrid rice breed with three-line or two-line method has successfully been applied in rice production.
From 1975, hybrid rice has gone through fast-speed development. More than 5000 varieties have been authorized by the government and planted for more than 500 million hm2 in China and play important function for national food safety [3, 4]. Rice blast disease caused by
2. The utilization of rice blast resistance genes
2.1 Identification of the resistant rice parents
The resistance level of parents is directly related with the resistance performance of hybrid rice. The resistance evaluation for breeding lines is a very important prerequisite work for resistance breeding of hybrid rice. For traditional breeders, field nursery or artificial inoculation with blast isolates in greenhouse was normally used for resistance identification. Amounts of rice lines with middle or high resistance have been identified in different provinces with diverse ecology. The detailed information was listed in Table 1. These identified rice materials provided rich selection as parents or resistant resource for hybrid rice breeding. As we know, genetic mechanism of rice blast resistance followed the gene for gene interaction. It was unclear about background and resistant genes in these materials, and the presence of one
|Sichuan||IR99–35, Miyang 46, IR 1544, Tetep, Gumei 2, 6326, Suhui162, and Suhui 527||[6, 7]|
|Heilongjiang||Suijing 12, Mudanjiang 26, Longdun 105, Longjing 20, Longjing 31, Dongnong 415, Songjing 9, Longdao 12, Hejiang 23, and Wuyoudao 3|||
|Guangdong||Sanhuangzhan 2 Hao, Qingliuai 1 Hao, Jingxian 89, IR36, and 28 Zhan|||
|Hunan||Xiangzao 143, Fengyuanyou 299, Jinyou 207, Liangyou 222, Quanfengyou 610, Hanyou 983, Lvyinzhan, Bingyou C278, Yuenongsimiao, and Zhuoliangyou 249||[10, 11]|
|Hubei||Zhenke, Jinlong 1, Fanyu 1, Ningwan 1, Sanqizao, Nanjing 15, Aiyinnuo, Jinzao 47, Yunjin 23, and Quanzhen 10||[12, 13]|
|Fujian||Yixiangyou 673, Dyou 15, Gangyou 148, Guyou 527, Jiafuzan, and Teyou 627||[14, 15]|
|Jiangsu||Longjing 968, Xiushui 134, Jia 58, Jindao 263, Huaidao 20, Yandao 10, and Gumei 4|||
2.2 Characterization and stack effective
Rgenes in hybrid rice
Following the clone of resistant genes and the development of related functional molecular makers, marker screening has been widely applied on resistance identification and innovation of parents of hybrid rice. Up to now, molecular makers of blast resistance genes,
The hybridization, backcross, and marker-assisted selection (MAS) were the general method for the introduction of
|R genes used||Variety improved||Variety type||Reference|
|Yandao 6 Hao||General cultivar|||
|Xiangwanxian 13||General cultivar|||
|Jin 23B||Maintainer line|||
|Rongfeng B||Maintainer line|||
|Shuhui527, Minghui 86, and Minhui 3301||Restorer line|||
|Chunhui 350||Restorer line|||
|Chuang 5S||Sterile line|||
|Zhenda A||Sterile line|||
With identification in the rice blast field nursery or functional marker detecting of major
For conventional rice breeding, all blast
In this chapter, it introduced the progress on identification of resistance resources and the utilization of blast resistance genes. Traditional cross technique, combined with MAS, has been used to transfer different major
This work was supported by Hunan Provincial Science and Technology Department (CN) (2018NK1020), Hunan Academy of Agricultural Science and Technology Innovation Project (2018ZD01-7), Hunan Academy of Agricultural Science and Technology Innovation Project (2017JC03), and Hunan Provincial Natural Science Fund Youth Fund (2018JJ3379).
Conflict of interest
The authors declared that there was no conflict of interest.