Crop plants can now be made to reproduce through seeds in the form of clones by plant biologists. The finding, which geneticists and plant breeders have been searching for a long time, may make it simpler to propagate highly productive, disease-resistant, or climate-tolerant crops and make them available to farmers worldwide. Many crops have been grown since the 1920s using hybrid seeds produced by crossing two kinds. These hybrids might excel in terms of yield or pest resistance, for example. However, hybrid crop seeds don’t always result in plants with the same traits. A significant development for global agriculture would be the ability to clone a plant from its seeds, creating an exact replica of that plant. Farmers may sow seeds from their own hybrid plants and reap the rewards of excellent yields year after year instead of spending money on pricey hybrid seeds each year, which are frequently out of the reach of farmers in developing nations. Unfertilized seed production is possible in about 400 species of wild plants. Apomixis is a mechanism that appears to have developed several times in plants, but not in species that are used to make commercial crops. According to Venkatesan Sundaresan, professor of plant biology and plant sciences at the University of California, Davis, “it’s a really desirable goal that might alter agriculture.”
The “Baby Boom” gene
The researchers found that the rice gene BBM1, which is a member of the “Baby Boom” or BBM family of plant genes, is expressed in sperm cells but not in eggs. BBM1 is expressed in the fertilized cell after fertilization, but—at least initially—this expression is derived from the male genome contribution. They reasoned that BBM1 activates an egg’s capacity to develop into an embryo. In order to stop the plants from going through meiosis, a sort of cell division that produces four daughter cells with half as many chromosomes as the parent cell, the researchers first utilized gene editing. Instead, the egg cells develop through the process of mitosis, receiving the mother’s entire chromosomal set. Then they made these egg cells express BBM1, which is something they would not have done naturally without fertilization. Sundaresan explains, “So we have a diploid egg cell with the capacity to generate an embryo, and that develops into a clonal seed.” The technique now has an efficiency of roughly 30%, but the researchers plan to improve efficiency with further study. According to Sundaresan, the strategy ought to be effective in other agricultural plants and cereal crops with comparable BBM1 genes.
Major findings from basic biology
According to Anne Sylvester, a program director at the National Science Foundation, which funded the research, “the beauty of this work is that it tackles fundamental problems in plant biology about how a fertilized egg begins to develop into a new plant.” By preventing the loss of advantageous features that can result from sexual reproduction, this fundamental concept, along with innovative asexual breeding technology, opens the door for advancements in plant agriculture.
The study is published in the journal Nature. The paper also includes writers from Iowa State University, INRA in Versailles, France, and UC Davis. The study was supported by the National Science Foundation and the Innovative Genome Institute, a collaboration between UC Berkeley and UC San Francisco that focuses on using genome editing to address global issues.