Cucumber plants are not simply male or female. They can be seven different sexes, depending on a complex mix of genetic and environmental factors. Some high-yielding cucumber varieties produce only female flowers, and scientists from the Boyce Thompson Institute for Plant Research (BTI) at Cornell University in the USA, and the Chinese Academy of Agricultural Sciences (CAAS) in China, have identified the gene duplication that causes this unusual trait.

Though researchers have known since the 1960s that there was a genetic cause for all-female flower-bearing plants, the exact location and sequence of the responsible segment of DNA was previously unknown. The researchers discovered the extra DNA by screening genome sequences from a core collection of 115 different cucumber lines. They generated a map of the 26,778 different structural variations that they found, some of which are associated with cucumber domestication.

According to BTI Professor Zhangjun Fei, who is one of the study leaders, they found the specific structural variation that is a duplication of about 30,000 bases, and the duplication was highly correlated with gynoecy. He added that "For female flowered-plants, there's a lot of potential for agricultural production."

Figure: Associate Professor Zhangjun Fei

For more details, read the news article at the BTI website.