Generating clonal seeds using non-reduction in female4 ( nrf4 ), a novel meiotic mutant of maize

The discovery of increased vigor and yield in hybrid corn compared to inbred lines dates to the early 20 ^th century. If hybrid vigor could be maintained across generations, it would revolutionize agriculture. A potential method to achieve this goal is asexual reproduction through seed (apomixis). We searched for mutants mimicking components of apomixis and here, we describe a novel meiotic mutant, non-reduction in female4 ( nrf4 ) of Zea mays (maize), that produces unreduced female gametes – an essential component of apomixis. By combining the nrf4 mutant with the previously described matrilineal / not like dad ( mtl / nld ) mutant, which leads to embryo development without paternal contribution, we successfully produced clonal seeds. This is an important step towards the engineering of clonally propagated hybrids in maize, the most widely grown crop world-wide. Our findings provide new avenues for the engineering of synthetic apomixis in crops.