An international team has successfully propagated a commercial hybrid rice line clonally via seed with 95% efficiency. This could lower the cost of hybrid rice seeds and make high-yielding, disease-resistant rice lines available to low-income farmers around the world. The study was published December 27 in Nature Communications.
Crop first-generation hybrids often show higher potency than their parental lines, a phenomenon called hybrid vigor. However, this does not last if the hybrids are bred together for a second generation. So if farmers want to use high-performing hybrid plant varieties, they will have to purchase new seeds each season.
Rice, a staple food for half the world’s population, is relatively costly to breed as a hybrid to improve yields by about 10%. This means that the benefits of rice hybrids have not yet reached many farmers around the world, said Gurdev Khush, an emeritus adjunct professor of plant science at the University of California, Davis. Working at the International Rice Research Institute from 1967 until he retired at UC Davis in 2002, Kush worked on developing a new high-yielding rice variety that won the World Food Prize in 1996.
One solution to this is to propagate hybrids as clones that remain identical from generation to generation without further mating. Many wild plants can produce seeds that are clones of themselves in a process called apomixis.
“Once you have a hybrid, if you can induce apomixis, you can plant it every year,” Kush said.
However, transplanting apomixis into major crops has proven difficult.
A step towards clonal hybrid seeds
In 2019, a team led by Professor Venkatesan Sundaresan and Assistant Professor Imtiyaz Khanday of the UC Davis Department of Plant Biology and Plant Sciences successfully apomixized rice, with about 30% of the seeds being clones.
Sundaresan, Khanday and colleagues from France, Germany and Ghana achieved 95% clonal efficiency using commercial hybrid rice lines and showed that this process can be sustained for at least three generations.
The single-step process includes three genes called MiMe that switch plants from meiosis, the process plants use to form egg cells, to mitosis, where the cell divides into two copies of itself. includes changing the Another genetic modification induces apomixis. The result is a seed that can grow into a plant that is genetically identical to its parent.
The method will not only allow seed companies to produce hybrid seeds more quickly and at scale, but also provide seeds that farmers can store and replant seasonally, Kush said. I’m here.
“Crop apomixis has been the subject of global research for over 30 years because it can make hybrid seed production accessible to everyone,” said Sundaresan. “Increased yields will help meet the global needs of a growing population without increasing land, water and fertilizer use to unsustainable levels.”
The results could also be applied to other food crops, Sundaresan said. In particular, rice is the genetic model for other cereals, such as maize and wheat, which constitute major staples of the world’s diet.
Khush recalls organizing a 1994 conference on apomixis in rice breeding. When he returned to UC Davis in 2002, he gave Sundaresan a copy of the meeting minutes.
“This was a long project,” he said.
Original: Breakthrough in rice farming to feed billions
Than: University of California, Davis
