Hybrid rice plant that can clone its seeds
Farmers need to buy hybrid seeds just once, not every year, scientists say.
doi:10.1038/nindia.2018.173 Published online 24 December 2018
Plant biologists have found a way that may enable poor farmers to do away with the need to purchase expensive hybrid seeds every year.
Indian origin researchers at the University of California, Davis report that they have solved a long-standing problem of hybrid seeds by discovering a new way to make exact replicas (clones) of the hybrid plants from seeds without fertilisation – a process called "apomixis"1.
For long, many crops have been grown from high yielding, disease-resistant or climate-tolerant hybrid seeds by crossing varieties chosen for their desirable traits. But the seeds of hybrid crops do not produce plants with the same qualities during reproduction and hence farmers cannot save the seeds for the next growing season. They end up paying for new hybrid seeds each sowing season.
UC Davis professor Venkatesan Sundaresan, postdoc Imtiyaz Khanday and co-workers discovered that the rice gene BBM1 – belonging to a family of plant genes called “Baby Boom” or BBM – is expressed in sperm cells but not in eggs. BBM1, they reasoned, "switches on the ability of a fertilised egg to form an embryo that grows (asexually) into a clonal seed.”
Asexual reproduction through seeds occurs naturally in many plant species but not in the important ones. The researchers used their method in the laboratory to produce viable seeds (progeny) from hybrid rice plants.
Farmers could thus replant seeds from their own hybrid plants and derive the benefits of high yields year after year, they report. The discovery, long sought by plant breeders and geneticists, could make it easier to propagate high-yielding, disease-resistant or climate-tolerant crops and make them available to the world’s farmers, the scientists report.
"Geneticists world over have been making efforts over the past 50 years to convert commercial hybrids of major cereal crops into apomicts,” Indian agricultural scientist Ebrahimali Siddiq told Nature India. Siddiq, whose research in genetics and plant breeding have helped develop high-yielding rice varieties such as the dwarf basmati, said the UC Davis work was a major scientific breakthrough.
While the discovery would help farmers, it would also impact the commercial interest of the (hybrid) seed industry, Siddiq, a former Deputy Director General in the crop science division of the Indian Council of Agricultural Research, said.
Sundaresan said at first sight, this might seem like a setback for hybrid seed companies but there will be plenty they can still do. “Rice is grown over such a vast climatic and geographical range that specialised hybrids will have to be developed for each region,” he told Nature India. The companies, he said, will continue to improve their hybrids. “It will be interesting to see how all this plays out in the years to come.”
Currently, the high cost of producing hybrid seeds is a major barrier to farmers in developing countries, especially South Asia and Africa. Sundaresan says if efficiently deployed, this method could potentially be a game-changer for poorer farmers, who would need to purchase hybrid seeds just once and plant the progeny seeds from their own harvest in subsequent seasons.
1. Khanday, I. et al. A male-expressed rice embryogenic trigger redirected for asexual propagation through seeds. Nature (2018) doi: 10.1038/s41586-018-0785-8