The genetic blueprint for a tree's sex is hidden in its telomeres

Nature · Published 20 October 2026 · Updated 21 October 2026 Swipe more like this →

In short: Populus deltoides, the eastern cottonwood, is a biological powerhouse capable of releasing 40 million seeds in a single season. However, its reproductive success depends on a precise genetic mechanism. Scientists have recently pinpointed the exact genomic region that determines whether a tree becomes male or female.

Populus deltoides is a widely distributed temperate tree native to a range spanning from Central and Eastern Canada down to Mexico. While it is a common sight across North America, its presence is highly varied, with different subspecies occupying specific niches. For instance, the subspecies P. deltoides wislizeni is primarily associated with the southwestern United States and northeastern Mexico, while P. deltoides monilifera serves as the state tree of Wyoming. The tree is recognized as one of the fastest-growing hardwoods in North America. In specific locations like the Mississippi River bottoms, it has been observed to grow between 3 and 5 meters in height annually for a few years. Its trunk can reach a diameter of 2.8 meters.

The species is dioecious, meaning individual trees are either male or female. This distinction is critical for forestry and environmental management because female catkins can create environmental issues. To manage this, breeding programs prioritize male varieties. Researchers have utilized Genome-Wide Association Studies (GWAS) to identify 801 sex-associated loci within the species. They successfully localized the sex determination region to the telomeric end of chromosome 19. The male catkins are reddish-purple and reach lengths of 8 to 10 centimeters. In contrast, the female catkins are green and can grow up to 15 to 20 centimeters long by the time they mature in early summer. These female structures eventually split to release their seed capsules.

By applying genomic selection (GS) models, scientists can now predict a tree's sex with high precision. Using specific single nucleotide polymorphisms identified through GWAS, researchers achieved a corrected prediction accuracy of 0.999 in certain models. This allows for the identification of sex in progenies with over 90% accuracy, providing a vital tool for high-precision breeding and sustainable forest management. The study utilized five full-sib families as a reference population to test these models. They evaluated 14 different statistical models across six different marker densities. The gradient boosting decision tree was specifically noted for providing the highest stability and accuracy among the tested options.

General information, not professional advice. Spotted an error? Flag the card or see corrections and complaints.

Intellect Plus is a visual educational discovery platform for exploring fascinating facts and ideas. Brain Food, Not Brain Rot. What is Intellect Plus?

Related

• A poplar was the first tree ever to have its whole genome read
• The loblolly pine is a genetic giant with a genome seven times larger than humans.
• Strictly speaking, a tree itself is neither male nor female
• Why the Eurasian aspen is a master of survival and forest regeneration
• This forest of 47,000 aspen trees is actually one single organism.
• Decoding the complex architecture of flowering plants
• The world's tallest flowering plant faces a shrinking future
• The biological blueprint: how seeds function as life bombs
• The architectural giants of the Asian rainforest hold a 100-million-year secret
• A twining vine's spin has nothing to do with the sun or the hemisphere
• The genetic clock that allows cannabis to bloom on its own
• The South American palm weevil is threatening California's iconic palm tree landscapes with destruction

More in Botany · More in Nature · Latest · A–Z · All topics