A date with plant tissue culture
Dates: The first candy
This ancient fruit and authentic candy originated in modern day Iraq. The first cultivation of dates probably occurred more than 8000 years ago. They are eaten fresh, dried, as syrup, alcohol, or even vinegar. Date palms are notoriously hardy and can withstand low rainfall and saline conditions. This is why many desert communities especially in the Middle East rely on these fruits for food security. The date fruit is incredibly nutritious. Even though they have a high sugar content, many varieties have low glycemic indexes; minimizing spikes in your blood sugar and helping you to stay full for longer.
Due to this fact, dates are increasingly being used as natural sweeteners in food and beverages. Together with an increased demand for dates in the feed and cosmetic industries, further economic growth in the date palm market is expected. Where in 2019 the date palm market was valued at around 13.4 billion U.S. dollars, with 4.5B. being accredited to tissue cultured dates, it is expected that the global date market value will increase to 16.25B. U.S. dollars by 2025.
There are over 200 varieties of dates with the Medjool, Deglet Nour, and Baja California being amongst the most popular. Date palms are dioecious, meaning the plants are either male or female. While the male palms provide pollen, the female palms provide fruit. These palms are tall, enduring, and bountiful. Most commercial varieties grow up to 21–23 meters high. When grown from seeds the palms can take between 7–10 years to produce commercially viable amounts of dates. However, yields between 70–140 kg per harvest season can be expected once they are mature. Although, fruits only occur once pollination has taken place with the help of wind or manually by farmers.
Degradation of date palm trees
Date palms are currently under threat. As much as 30% of the total production can be potentially lost due to pests and diseases. There are a whole host of pests, diseases and fungi that are plaguing the industry. For instance, fusarium wilt disease has no known treatment. So, prevention and propagation of fusarium wilt-resistant date palms has become crucial. Coupling this with increased salinity and harsher droughts in many regions where dates thrive, date palm production is declining. Therefore, the need for more high salinity and disease resistant date cultivars is growing.
The shortfall of using offshoots
Date palms can grow individually or can produce offshoots. Therefore, two conventional methods of date palm propagation include seed and offshoot propagation. However, seeds have a fifty-fifty chance of being male or female. And males don’t produce fruit. Therefore, many farms make use of offshoot propagation.
A date palm tree can produce around 20-30 axillary buds. These buds can take around three years to differentiate into offshoots. An offshoot then takes three to four years to be suitable for propagation. The survival rates of these offshoots are low due to pests and diseases. Additionally, not all cultivars produce many offshoots. The use of offshoot propagation is thus unreliable and time consuming. Therefore, this method is not suitable for commercial date palm agriculture. However, another propagation method exists.
Advantages of plant tissue culture for date palms
As date palms are dioecious, farmers want to maximize the number of female plants they have. This is to prevent using too much of the available resources on fruitless male plants. Additionally, seed propagation delivers plants which may not be true-to-type (identical to the mother plant). These palms also have a long delay before fruiting. Therefore, propagation must be aimed at producing high quality females and plant tissue culture (PTC) techniques can deliver this. This technique is also useful for cryopreservation; the storing of plant material in liquid nitrogen, of important varieties. The benefits of plant tissue culture in date palm also extend to its ability to create synthetic seeds and disease resistant varieties. This higher resistance to diseases, combined with superior and uniform quality are central advantages tissue culture brings to the production of date palms.
Plant tissue culture methodologies
Successful propagation of dates has occurred with organogenesis (OG) and somatic embryogenesis (SE). Both of these methods have shown positive results and these techniques have been employed by some PTC laboratories. The most successful SE propagation makes use of the shoot tip tissue from an offshoot. However, organogenesis using inflorescence tissues as explants has shown promising results as well. This method has shown high survival rates among other date palm explants that have been used for tissue culture. The inflorescence is a cluster of flowers that appear on a stem. In date palms these occur beneath the palm leaves. This tissue has proven to have great multiplication potential as well.
Economic advantages of date palm tissue culture
The major economic advantages of date palm plant tissue culture are to be able to maintain and preserve true-to-type genetics. There is a high probability of decrease in quality when date palms are propagated using seeds as they are dioecious. Also, using offshoot propagations put the mother-palms at higher risk of infections. Whereas PTC is safe.
By using tissue culture, date palms can be grown in a safe way with a much shorter time span than when traditional methods of seed and offshoot propagation are used. This increases the efficiency of production and results in the ability of creating larger scale and more profitable farms. As the demand for high quality dates is constantly rising, the use of micropropagation is becoming more and more of a necessity. Conventional propagation techniques cannot keep up with the demand and are struggling against several environmental factors. Due to these factors, the demand for tissue cultured dates is expected to keep rising.
So there’s no better time or date to start using plant tissue culture!
For more informational posts on plant breeding and tissue culture, keep checking this space!
By Christos Tripodis | 8-February-2022
About the author
Christos Tripodis was raised in the windy city of Port Elizabeth, South Africa. This southern coastal city is now known as Gqebreha and is the Bottlenose Dolphin Capital of the World. During his time at Nelson Mandela University, Christos focused on physics and biology. Eventually graduating with a BSc Honours in Botany with a focus in ecophysiology and phytoremediation. Currently, Christos is using his communication skills and understanding of botany as an Inside Sales Representative at Lab Associates B.V. When he is not reading or writing you can find him botanizing or in the ocean. His other passions include cooking, martial arts, and languages.
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