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Following the ancestor of the olive

Researchers have discovered an ancient variety of olive tree that has existed in Israel much longer than the Syrian variety and are now trying to attribute it to a certain period and understand when and where it began to grow

Photo by Prof. Oz Barzani and Prof. Arnon Dag, Volcani Institute
Photo by Prof. Oz Barzani and Prof. Arnon Dag, Volcani Institute

Throughout history, the olive was used mainly for food, oil production, cooking, lighting, worship and medicine. The olive tree has great cultural, historical, religious and environmental importance in the Land of Israel, which is in the heart of the area where the olive was first domesticated, 7,000-5,000 years ago. For example, the world's oldest textile house (facility for extracting and producing olive oil) is found in excavations on the seashore in the Kfar Samir area of ​​Haifa and remains of ancient textile houses from different periods are scattered all over the country. Therefore it is important to characterize and preserve the oldest olive varieties that are found here.

What is the question? What is the origin of an ancient olive variety that was replaced by the Syrian variety?

Prof. Oz Barzani and Prof. Arnon Dag from the Agricultural Research Administration, Volcani Institute, research ancient olive trees in Israel, 400-300 years old or older. Their main purpose is to characterize the local varieties, descendants of ancient varieties, and to preserve them. "We can guess the age of an olive tree by the circumference of its trunk. For us, a tree with a girth greater than two meters is defined as ancient. We are also interested in preserving the ancestor of the cultivated olive, assuming that there are last remnants of wild olives in the country; We can locate them, examine whether their properties are adapted to the environmental conditions in which they grow (such as dryness) and preserve them and the genetic pool of ancient olive trees that grow in culture (the product of clarification and improvement that lasted thousands of years), as well as in collection plots (which exist at the Gilat Research Center in the North of the Negev and Ramat Park the philanthropist in the Zichron Ya'akov region). This is due to their importance to the local heritage and culture," explains Prof. Barzani.

So far, the researchers have sampled and mapped dozens of ancient olive trees in more than 30 plantations across the country, from north to south. Prof. Barzani says: "The trees and varieties we have sampled so far and growing in the collection plots are already bearing fruit. Varieties growing together under the same conditions in the collection plots make it possible to examine the characteristics of the trees (for example, resistance to pests and diseases) and agricultural properties of the olives, such as the growth period, the amount of the crop, the amount of oil in relation to the weight of the fruit and the properties of the oil."

Ancient olive trees. Photo by Prof. Oz Barzani and Prof. Arnon Dag, Volcani Institute
Ancient olive trees. Photo by Prof. Oz Barzani and Prof. Arnon Dag, Volcani Institute

In a molecular and phenotypic study, the researchers discovered that 90% of the olive trees they sampled belong to one variety - the Syrian variety (originating in Tyre, Lebanon). In addition, they discovered that more than 80% of the trees they sampled were put together on a tree (an operation in which a branch from one tree - a "rider" - is assembled on a branch of a tree or seedling from another genetic source of the same species to give it the same fruit properties and resistance to soil conditions). They also found that within 10% of the trees there is a variety that is probably older than the Syrian variety, meaning that it has existed in Israel much longer than it.

In their latest study, which won a grant from the National Science Foundation, the researchers sought to examine and characterize this ancient strain. Prof. Barzani says, "We hypothesize that at a certain point in history, the Syrian variety replaced the same ancient variety and the form of replacement was the assembly of the Syrian variety on the ancient variety. That is why we often find it as a frankincense of ancient trees. All the archaeological findings (such as shells found in excavations near ancient textile mills and pollen grains in orchards) testify to the Fertile Crescent region (which includes Israel, Cyprus, Lebanon, Jordan, Syria, Iraq and Egypt) as the one where the domestication of the olive tree and other agricultural crops such as wheat began , barley and the fermented legumes (hummus) and lentils. It is possible that the ancient olive variety is close to the beginning of the domestication of the olive."

In order to associate the ancient species with a certain period and to understand when and where humans began to grow it, the researchers examine the characteristics of its pods and compare them to those of pods from different historical periods.

In order to succeed in associating the ancient variety with a certain period and to understand when and where humans began to grow it, the researchers, together with Elad Ben Dor, a master's degree student, examine the characteristics of its pods and compare them to those of pods from different historical periods ("Each variety has its own unique pods", explains Prof. Barzani). This is through molecular and morphometric methods (shape and size analysis), computational means and image processing software. "To associate pods with varieties, we analyze their geometry, length, width and surface area and other shape characteristics. We photograph them and translate the photograph into measures by which we can characterize them. This is how we built a sort of 'atlas' of seed pods from around the Mediterranean; Every whole kernel that we examine is photographed and compared to the atlas and thus associated with a certain variety," explains Prof. Barzani.

The researchers have not yet discovered the age of the ancient variety and when it was domesticated, but genetic findings show that it belongs to the remains of Byzantine agriculture (familiar olive trees) that existed in the Negev settlements about 1,500 years ago. "Byzantine farmers grew olive trees there. We characterized the genetic background of trees from the Shveta area, in collaboration with Prof. Guy Bar-Oz from the Department of Archeology at the University of Haifa, and we know that it characterizes the same ancient variety."

To identify and characterize the ancient variety, the researchers also use chemical tools - extracting the oil from the olive and characterizing its fatty acid profile. In addition, they are trying to develop tools to decipher the DNA extracted from ancient fossils.

"In the current research, we have discovered so far that the Syrian variety replaced the ancient variety by mounting it on it. We hypothesize that local farmers from the Land of Israel did this because they wanted to breed a more successful variety that arrived in our area, with a high yield, high oil content and large fruit. Using the research tools at our disposal, we are trying to understand what are the agricultural features of the Syrian variety that make it more successful, and when exactly the exchange was made. In this way, we will be able to decipher the background and history of olive cultivation in the Land of Israel, a process that began about 6,000 years ago," Prof. Barzani concludes.

Life itself:

Prof. Oz Barzani, 59 years old, married, lives in Ramat Gan. His occupation is his main hobby ("I've been blessed") and he also works in art, loves books, listens to podcasts (in traffic jams) and loves to travel in nature. Prof. Arnon Dag, 57 years old, married + three sons (21, 15 and 15), lives in Moshav Lakish. In his free time he likes to travel.

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