Qatar experts closer to solving the riddle of date palm gender.
Researchers at Weill Cornell Medical College in Qatar (WCMC-Q) have identified a region of the date palm genome linked to gender, making it possible for the first time to easily identify male and female trees.
This crucial piece of information will greatly facilitate additional genetic studies as well as cultivation and propagation, it was announced yesterday.
"Our evidence shows that date palm employs an XY system of gender inheritance similar to that of humans," said Joel Malek, director of the genomics lab and senior author of the study, which was published online yesterday 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, he pointed out.
"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," Malek stated.
Date palm is a dioecious species, which means 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," observed Malek.
Malek and WCMC-Q colleagues sequenced a draft version of the date palm genome two years ago.
The WCMC-Q research team co-operated with the Biotechnology Centre at the Ministry of Environment in Qatar, which provided date palm samples to support the 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 Biotechnology Centre director Masoud al-Marri.
He explained that 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.
"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," said Robert Krueger, horticulturist with the National Clonal Germplasm Repository for Citrus and Dates, US, which provided samples of backcrossed date palms for the research.
The WCMC-Q research used samples that were part of a date palm breeding programme 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 was curator of the collection.
The repository is operated by US Department of Agriculture'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," Malek recalled while adding that varieties of dates are notoriously hard to identify even by experienced growers.
"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," Krueger maintained.
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.
Gulf Times Newspaper 2011
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