Under a midday summer sun in California's Sacramento Valley, rice farmer Peter Rystrom walks across a dusty and bare plot of land, dry soil crunching (碎裂) beneath each step. In a typical year, he'd be walking across green rice fields in inches of water. But today the soil is dry and baking in the 35℃ heat. It hasn't rained for 4 weeks in a row.
"Climate change is expected to worsen the state's extreme swings in rainfall," researchers reported in Nature Climate Change in 2018. Low water levels in rivers have forced farmers like Rystrom, whose family has been growing rice on this land for four generations, to reduce their water use.
"If we lose our rice crops, we have to deal with severe food crisis. Climate change is already threatening rice-growing regions around the world. This is not a future problem. This is happening now," says plant geneticist Pamela Ronald of the University of California, Davis, who identifies genes in rice that help the plant stand up to dryness, disease, flood, etc.
To save and even boost production, rice growers, engineers and researchers have turned to water-saving irrigation (灌溉) routines. Building canal systems and reservoirs (水库) can help farmers dampen their fields. But for some, the solution to rice's climate-related problems lies in enhancing the plant itself. They hold that establishing rice gene banks that store hundreds of thousands of rice varieties ready to be bred into new, dryness-tolerant varieties is more practical and effective. Solutions may be hidden in the DNA of those older breeds.
Three decades have passed since its initial development, and some researchers are looking beyond the genetic variability preserved in rice gene banks, searching instead for useful genes from other species, including plants and bacteria. But picking genes from one species and putting them into another, or genetic recombination, remains debatable. The most famous example of genetically changed rice is Golden Rice (GR). "Looking ahead, it will be crucial for countries to embrace GR rice. But it will take time," says Ismail, principal scientist at IRRI,
