Researchers at Weill Cornell Medicine – Qatar (WCM-Q) can now predict whether a date palm seed will produce a male or female plant with effectively 100% accuracy – with huge implications for the commercial use of the plant.

For farmers growing date palms and harvesting the fruit, it is important to have as many female plants as possible to maximise crop yields. Conversely, city planners and landscape gardeners who plant palm trees for aesthetic reasons prefer male plants, as they do not produce fruit which must be cleared up when it drops.
The team led by Dr Joel Malek, assistant professor of genetic medicine and director of the Genomics Core at WCM-Q, already knew that the sex of the date palm plant is determined by the XY system, whereby the male of the species determines the sex of the offspring, similar to the way that human gender is determined. They also knew that a large region of genes appeared to be always associated with gender but were unclear on the specific DNA responsible.
That uncertainty has now been solved, and in doing so the research team has discovered how to predict the sex of all 14 palm tree species within the Phoenix genus – the genus that contains the date palm. They did this by decoding the genome of each species to calculate which genes appeared in the male plants but not the females. 
Dr Malek said, “The mechanism was narrowed down to four genes that every male plant in the entire genus had, but that were absent in the female plants. Essentially, those four genes are responsible for a tree producing pollen.”
He added that the Phoenix genus was one of only a few examples where the sex determinants are the same across the entire genus.
The discovery, which has been reported in the high impact journal Nature Communications could have major implications for both commercial agriculture and horticulture.
Dr Malek said, “Farmers must traditionally wait four or five years to discover whether the trees that they have planted will yield fruit or pollen so genetic testing of the seeds can ensure a high ratio of female plants are grown, with only a few male plants being cultivated for pollination purposes. At the same time, the genetic test can be used on other species in the genus that are also important such as Canary Island date palm which is extremely widespread in the world at large for landscaping.”
Future research will see Dr Malek and his team identifying the genes which control features such as the date’s size, sweetness and texture, along with its resistance to certain diseases and stress factors like drought.

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