New flood-tolerant rice offers relief for world's poorest farmers
Each year millions of small farmers in the poorest areas of the world lose their entire crops to flooding. Although 24% of the global rice crop is grown in paddies, most rice varieties will die if fully submerged for more than three days. In India and Bangladesh alone, submergence destroys 4 million tons of rice each year, enough to feed 30 million people.
About 50 years ago, breeders discovered an unusual and ancient variety of rice that could withstand 2 weeks of complete submergence. Using conventional approaches, breeders tried to introduce this submergence tolerance trait into rice varieties favored by farmers in India and Bangladesh. However, because the breeding was imprecise, the resulting varieties were rejected by farmers. In the 1990s, rice breeder David Mackill (University of California, Davis) and graduate student Kenong Xu (University of California, Davis) demonstrated that tolerance to complete submergence mapped to the Submergence tolerance 1 (Sub1) Quantitative trait locus (QTL)
In 1996, Ronald began a project with Mackill and Xu, funded by the USDA, to isolate the genes at the Sub1 locus. Over a period of 10 years, Dr. Xu carried out fine mapping and physical isolation of the Sub1 gene in the Mackill and Ronald laboratories at the University of California, Davis (Xu. et. al., 2000). While working as a postdoctoral fellow in Ronald’s laboratory, Xu identified and sequenced the Sub1 QTL genomic region, revealed that it carried three ethylene response transcription factors (ERF) and demonstrated that one of the ERFs, designated Sub1A, was up-regulated rapidly in response to submergence. Xu and Ronald further demonstrated that overexpression of Sub1A conferred robust tolerance to submergence in genetically engineered plants (Xu. et. al., 2006). This work revealed an important mechanism with which plants control tolerance to environmental stress and set the stage for in-depth molecular-genetic analyses of Sub1A-mediated processes (Jung et al., 2010).
Sub1 function: Dr. Sigrid Heuer (International Rice Research Institute) further advanced the analysis of genetic variation at the Sub1 locus. As part of a third USDA grant (to Pamela Ronald and Professor Julia Bailey Serres (University of California, Riverside)), postdoctoral fellow Takeshi Fukao was instrumental in advancing mechanistic understanding of Sub1 function (Fukao et al., 2006).
Sub1 breeding: Using the detailed genetic information about the Sub1 locus, Mackill and and Abdel Ismail’s teams at the International Rice Research Institute (IRRI) generated and released several Sub1A varieties (developed through marker-assisted breeding) in seven countries. In 2013, with support from the Bill and Melinda Gates Foundation, Sub1 rice reached over 4 million farmers.
For more information see:
Xu K, Ismail A, and Pamela C. Ronald. 2014. “Flood Tolerance in Rice” in “ Plant Abiotic Stress 2nd Edition”. Wiley-Blackwell Publishing. Matt Jenks and M. Hasegawa, Eds.
A user-interactive web tool for RiceNet-based selection of candidate genes regulating stress tolerance is publicly available at http://www.functionalnet.org/ricenet
- Modern MacGyver: The Indestructible Rice – World Science Festival
- Tomorrow’s Table – Blogging from Bangladesh(Pam Ronald’s blog)
- Bill Gates – We Need Productivity and Sustainability(The Gates Notes)
- Grains of Truth(Reed Magazine)
- Big Ideas for Our Future Health, Mind and Boddies – Smart Pills, Super-Rice, Mind Control, Organs(Popular Mechanics)
- Asian farmers will get a disaster-proof version of an essential crop (Popular Science)
- Waterproof rice coming soon (Nature Blogs)
- USDA Discovery Award Recognizes Rice Research (UC Davis News and
- UCD rice research may help feed world (UC Davis News and
- Waterproof rice passes field trials (Commodity Online)
- UCR professor helps develop new rice (The Press-Enterprise)
- “Waterproof” rice to tackle crop loss in India (The Economic
Scientists Create Flood-Resistant Rice (SciDev.Net)
- Plant breeding: Rice in deep water (Commentary in Nature by T. Sasaki)
- This rice refuses to panic in floods (Sacbee)
- Waterproof rice fights flood and famine (Science museum antenna)
- Rice Gets Flood Insurance (Science magazine)
- New Gene Allows Rice to Survive Submersion(Scientific American)
- Gene discovery could lead to flood-resistant rice (SciDev Net)
- ‘Waterproof’ rice outlasts floods (Bangkok Post)
- Rice Gene Found to Help Crops Survive Extended Paddy Flooding (bloomberg news)
- Do you want rice with that? (Nobel Intent)
- Gene breakthrough could revolutionise rice crop(Food productiondaily.com)
- RP, US scientists identify flood resistance gene in rice (ABS-CBN Interactive)
- Scientists identify flood-tolerant gene of rice(China View)
- Rice made to breathe underwater (Nature News)
- Nature Podcast 10 August 2006 (Nature Podcast)
- Philippine, US researchers discover flood resistant rice gene(Agence France Presse, Manila)
- Gene discovery to help rice yields threatened by floods (Agence France Presse, Paris)
- Flood-tolerant paddy variety released (The Hindu)