WCMC-Q researchers have identified a region of the date palm genome linked to gender, making it possible for the first time to quickly and easily identify male and female trees, a crucial piece of information which will greatly facilitate additional genetic studies as well as cultivation and propagation.
“Our evidence shows that date palm employs an XY system of gender inheritance similar to that of humans,” says Joel Malek, director of the genomics lab and senior author of the study, which was published online today by the journal Nature Biotechnology. “How date palm gender is determined has been a question for thousands of years with numerous theories presented in the past. We now have the first DNA sequence evidence that it is under genetic control though the gender control region appears quite small making its discovery difficult,” he adds.
Date palm is a dioecious species, that is, individual plants are either male or female. Consequently, half of the seedlings grown for cultivation will be males and half will be females. Female trees bear the fruit, making them much more valuable than male trees, which serve only as pollinators. Early identification of the more valuable female trees is difficult because it takes about five to eight years for female seedlings to bear the distinguishing fruit.
“A simple and reliable way to distinguish between male and female seedlings has long been sought not only for agricultural purposes but also to promote basic date palm studies, which have been hindered by dioecy and long generation times,” says Malek. Two years ago, he and WCMC-Q colleagues sequenced a draft version of the date palm genome.
The WCMC-Q research team cooperated with the Biotechnology Center at the Ministry of Environment in Qatar which provided date palm samples to support their research. “Identifying the genes related to specific date palm characteristics will certainly help us find solutions to problems faced by date palm plantations in Qatar, especially as far as diseases affecting date palm trees are concerned.”, said Masoud Al-Marri, Director, Biotechnology Center, Ministry of Environment.
“This research will also explore the unique characteristics of the date palm tree such as its tolerance to salinity and high temperatures, and ways of making other plants tolerate such extreme conditions by genetic modification, i.e. transferring genes from date palm trees to other plants,” he added.
“The date palm represents a treasure of genes that can help other plants and trees survive harsh conditions. We would like to thank WCMC-Q team for their valuable research, and we look forward to more cooperation between the medical college and the Biotechnology Center at the Ministry of Environment,” he added.
“This research will definitely benefit both agriculture and environment sectors. It will make it possible for the first time ever to quickly and easily identify male and female date palm trees, saving a lot of time and effort. This scientific breakthrough is an example of how we can harness modern technology for the advancement of science,” he concluded.
“This project will contribute to a more complete understanding of the date palm genome, which, in turn, will provide tools for investigating useful traits, such as disease resistance and salinity tolerance,“ says Robert Krueger, horticulturist with the National Clonal Germplasm Repository for Citrus and Dates, who provided samples of backcrossed date palms for the research.
The WCMC-Q research used samples that were part of a date palm breeding program carried out in California from 1948 to 1974 and incorporated into a national repository, which maintained the lines as part of a mission of conservation of genetic resources, says Krueger, who served as curator of the collection. The repository is operated by USDA’s Agricultural Research Service.
“Use of the back crossed males greatly simplified our research because it gave us access to pure lines of male date palms,” says Malek. Varieties of dates are notoriously hard to identify even by experienced growers, he adds.
“This project also validated the genetic identity of the backcrossed males as well as female varieties maintained in the US against same-named varieties from the Middle East. This reinforces the integrity of the collection after being maintained for many years in several different locations,” says Krueger.
The date palm plays a significant role in agriculture throughout the Middle East, Northern Africa and Pakistan. The fruit is a major source of nutrition in the areas, and the tree itself plays an important role in the development of sustainable agriculture in many drought and saline-affected regions of the world. References in the Qur’an have kept alive the use of dates for medicinal purposes over the centuries.