创新背景

自20世纪20年代以来，许多作物都是由两个品种杂交产生的杂交种子种植出来的。这些杂交品种在产量或抗虫害等方面具有优越的品质。但是杂交作物的种子不能产生具有相同品质的植物。

创新过程

利用植物的种子生产出一株植物的复制品的能力将是世界农业的一项重大突破。每年购买昂贵的杂交种子往往超出了发展中国家农民的财力，农民可以从他们自己的杂交植物中重新种植种子，并获得年复一年的高产效益。

大约400种野生植物可以在不施肥的情况下产生有活力的种子。这个过程被称为无融合生殖，似乎在植物中已经进化了很多次，但在商业作物物种中却没有。

博士后研究员Imtiyaz Khanday和加州大学戴维斯分校植物生物学和植物科学教授Venkatesan Sundaresan及其在加州大学戴维斯分校、爱荷华州立大学和法国INRA的同事的发现是向前迈出的重要一步。

khan和Sundaresan发现，水稻基因BBM1属于植物基因家族“婴儿潮”(Baby boom，简称BBM)，它在精子细胞中表达，而不在卵子中表达。受精后，BBM1在受精卵中表达，但至少在最初，这种表达来自于雄性对基因组的贡献。他们推断，BBM1开启了受精卵形成胚胎的能力。

研究人员首先使用基因编辑来阻止植物经历减数分裂。减数分裂是一种细胞分裂，会产生四个子细胞，每个子细胞的染色体数量是母细胞的一半。相反，卵细胞是通过有丝分裂形成的，从母亲那里继承了一整套染色体。然后，他们让这些卵细胞表达BBM1，如果没有受精，它们通常不会表达BBM1。所以会有一个二倍体卵细胞，它有能力产生胚胎，并生长成克隆种子。

到目前为止，这一过程的效率约为30%，但研究人员希望通过更多的研究来提高效率。这种方法应该适用于其他具有相同BBM1基因的谷类作物，以及其他农作物。

创新价值

这项研究解决了植物生物学中有关受精卵如何开始发育成一种新植物的基本问题，这一基本认识，加上新的无性繁殖技术，通过避免有性繁殖可能发生的有益性状的损失，为植物农业的突破打开了大门。

创新关键点

研究人员发现，水稻基因BBM1属于植物基因家族“婴儿潮”(Baby boom，简称BBM)，它在精子细胞中表达，而不在卵子中表达。受精后，BBM1在受精卵中表达，但至少在最初，这种表达来自于雄性对基因组的贡献。他们推断，BBM1开启了受精卵形成胚胎的能力。

Rice plants were propagated by seed cloning

The ability to produce a replica of a plant from its seeds would be a major breakthrough in world agriculture. Buying expensive hybrid seeds each year is often beyond the means of farmers in developing countries, who can replant seeds from their own hybrids and reap high yields year after year.
About 400 wild plant species can produce viable seeds without fertilization. This process, called apomixis, seems to have evolved many times in plants, but not in commercial crop species.
The findings by Imtiyaz Khanday, a postdoctoral researcher, and Venkatesan Sundaresan, professor of plant biology and plant sciences at UC Davis, and colleagues at UC Davis, Iowa State University, and INRA, France, are an important step forward.
Khan and Sundaresan found that the rice gene BBM1 belongs to the "Baby boom," or BBM, family of plant genes, which is expressed in sperm cells but not in eggs. After fertilization, BBM1 is expressed in the zygote, but at least initially, this expression comes from the male contribution to the genome. BBM1, they reasoned, turned on the ability of fertilized eggs to form embryos.
The researchers first used gene editing to stop plants from going through meiosis. Meiosis is a cell division that produces four daughter cells, each with half the number of chromosomes as the mother cell. Instead, egg cells are formed by mitosis, inheriting a full set of chromosomes from the mother. They then asked the eggs to express BBM1, which they would not normally do if they were not fertilized. So you have a diploid egg cell, which has the ability to produce an embryo, which grows into a cloned seed.
So far, the efficiency of the process is about 30 percent, but the researchers hope to improve it with more research. This approach should be applied to other cereal crops with the same BBM1 gene, as well as other crops.