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Research

Feb 19th, 2024
Revolutionizing Plant Cloning: Boosting Global Agriculture?

Can better rooting in plant cloning improve crop variety, cost, and climate resilience?

  • Life Sciences

In an extensive and multi-phased international study that lasted for eight years, led by researchers from the School of Plant Sciences and Food Security at TAU and the Volcani Institute, there were new compounds developed that significantly increased the rooting efficiency of cuttings (typically small branches) taken from mature trees. The researchers explain that getting cuttings to root is a critical component in modern agriculture: “A significant number of fruit trees, as well as forest trees and ornamental plants, are today based on cutting propagation: the creation of plants that are genetic clones of an individual with desirable characteristics. Improving the rooting process can contribute to global agriculture in various aspects: developing new, high-quality varieties, lowering prices for farmers and consumers, increasing the economic viability of new cultivars of crops, and adapting crops to the changing climate conditions".

 

Enhancing Nature

The research was led by Dr. Roy Weinstain, research student Ohad Roth from the School of Plant Sciences and Food Security at TAU and Dr. Einat Sadot from the Institute of Plant Sciences at the Volcani Institute. Also participating in the research were Dr. Inna Vints from the TAU School of Plant Sciences and Food Security, Prof. Nir Ben-Tal and Dr. Amit Kessel from the Department of Biochemistry and Molecular Biology at TAU, Sela Yechezkel, Ori Serero, Avi Eliyahu, Pan Tzeela, Dr. Vikas Dwivedi, Dr. Mira Carmeli-Weissberg, Felix Shaya, and Dr. Adi Faigenboim-Doron from the Volcani Institute and Prof. Joseph Riov from the Faculty of Agriculture of the Hebrew University of Jerusalem. The study was in collaboration with researchers from the USA, Germany, Denmark and England and published in the prestigious journal Nature Biotechnology.

 

Left to right: Dr. Einat Sadot, Dr. Roy Weinstain, Ohad Roth & Sela Yechezkel. Photo credit: The Volcani Institute.

Left to right: Dr. Einat Sadot, Dr. Roy Weinstain, Ohad Roth & Sela Yechezkel. Photo credit: The Volcani Institute.

 

Dr. Sadot explains: “vegetative propagation through cuttings is a method used to propagate plants asexually - not through seeds. In this method, a branch is selected from a plant with desirable properties (e.g. fruit taste, drought resistance, disease resistance, etc.), and parts of that branch, called cuttings or propagules, are exposed to conditions that cause them to grow roots and become independent plants. The new individuals created this way were actually clones with the same genetics as the mother plant. For a crop to be economically viable, rooting percentages of at least 50-60% are necessary, and this figure is a significant consideration for farmers. Rooting percentages vary between different genuses of the same family, between different species of the same genus, and even between different cultivars of the same species, and there are important agricultural plants that are particularly difficult to root".

 

Cutting-Edge, Literally

To improve the percentage of plants developing roots, it is necessary to expose cuttings to the plant hormone auxin – a procedure that was discovered more than 70 years ago and has hardly changed since. Dr. Weinstain: “The effectiveness of the existing auxin treatment varies from plant to plant. Numerous agriculturally important plants hardly respond to the standard auxin treatment in terms of root formation that couldn't be commercialized. In our study, we sought to increase the effect of auxin on the cuttings. Evidence in the scientific literature and observations by experts in the field led us to address the question: will a slow release of the auxin in the plant increase the rooting success of the cuttings?” To do this, the researchers first created a ‘library’ of materials based on synthetic auxin conjugates – molecules in which a synthetic auxin attaches to another chemical group that neutralizes its activity but can be released slowly in plant cells. The library was examined using cuttings from a mature Eucalyptus grandis tree, in which the standard auxin treatment reached low rooting percentages of only 10-15%.

 

Research student Ohad Roth explains: “The initial examination identified several compounds that have a positive effect on the rooting process, and further research focused on the most effective one. We discovered that this compound enables a combination of high permeability to the plant with a prolonged release of the active substance, the synthetic auxin, so that the auxin stays in the plant much longer, up to a week and a half". Indeed, the upgraded treatment increased the rooting percentage of the Eucalyptus grandis cuttings to 60% – up to 6 times higher than the rooting percentages found using the standard method.

 

Later, to more deeply understand the new compound’s mode of action, the researchers used the model plant Arabidopsis thaliana. They discovered that the synthetic auxin used in the new material is more stable (breaks down more slowly) in the plant cells compared to the auxin used in the standard treatment. In addition, the researchers identified a family of enzymes in the plant that are responsible for the release of the synthetic auxin. By modeling these enzymes' structure and biochemical properties, they have identified important characteristics of their activity.

 

In the next step, the researchers wanted to see if similar enzymes are also present in other plants – assumingly their presence will allow the new material to be used as well as in other crops. They discovered that this family of enzymes is very ancient and preserved throughout evolution in every tree tested. In light of the encouraging findings, they began to test the effectiveness of the materials they developed on various crops.

 

Transforming Argan Trees to Agricultural Crops

One of the most meaningful crops examined in the study is the argan – the Moroccan oil tree. The researchers: “The global demand for argan oil is increasing by the years because of its incorporation to a large variety of food, health and skincare products. But to date, the almost exclusive source of this oil is the fruits of argan trees that grow endemically in Morocco and multiply by sexual reproduction, i.e. through seeds. All efforts to turn argan into an agricultural crop, which can be propagated by rooting cuttings, have failed – including attempts here in Israel. In our research, we took cuttings from several argan trees growing in Israel, exposed them to the material we developed, and, this way, succeeded in producing large seedlings from elite selections. In collaboration with the Kibbutzim of Ketura, Beit Kama, Hatzerim and Samar, we planted argan plots based on cuttings from individual specimens, which were rooted using the new rooting material, and we are now examining the possibility of turning them into an agricultural crop". 

 

The Beautiful Argan Tree

 

Encouraging results were also observed in experiments with cuttings from apple trees rootstocks, poplar and other varieties of eucalyptus. Higher rooting percentages were achieved in all of them – twice as high or more when compared to the standard auxin treatment. The researchers conclude: “During the research, we developed a material that significantly improves the rooting percentages of cuttings from mature trees. The development could be significant for global agriculture in three aspects: 

 

● Cost reduction: improving the efficacy of the rooting procedure may significantly reduce the cost of procuring seedlings for farmers and, ultimately, the agricultural produce for consumers. 

● Improved produce quality: Thanks to the new method, more high-quality cultivars could developed and traded, negating the need to ‘compromise’ on lower-quality varieties simply because they have high rooting rates.

● Environmental compatibility: developing new crop cultivars that adapt to climate change conditions is imperative to sustain agricultural output. The new method can expedite this process and make it more efficient.

 

In follow-up studies, we plan to deepen the understanding of the new substances’ mechanisms of action and look for additional compounds, perhaps even more effective ones, that can be used as conjugates to slow down the release of auxin in the plant.”

Research

Feb 15th, 2024
Are We Close to Ending Alzheimer's Memory Loss?

TAU Researchers Successfully Prevent Memory Deterioration in Alzheimer’s in an Animal Model

  • Medicine

In 2022, a team of researchers from the laboratory of Prof. Inna Slutsky from the and the at TAU uncovered a pathological brain phenomenon in an animal model that precedes the first appearance of Alzheimer’s disease symptoms by many years. This is an increased activity in the hippocampus during the states of anesthesia and sleep, which results from damage to the mechanism that stabilizes the neural network.

 

Breakthrough in Alzheimer's Study

In the current study published in Nature Communications, Prof. Slutsky’s laboratory team, in collaboration with the Safra Center for Neuroscience at the Hebrew University, found that suppression of neuronal activity in a small nucleus in a specific area of the thalamus (which regulates sleep states) caused a decrease in pathological activity in the hippocampus and prevented the deterioration of the memory in Alzheimer’s in an animal model. The researchers hope that their research will speed up the start of clinical trials in humans, lead to progress in the fields of early detection and prevention of the onset of dementia symptoms in Alzheimer’s disease, and in the field of treating cognitive impairments caused by surgery (POCD - Postoperative Cognitive Dysfunction).

 

Doctoral Student Shiri Shoob

Doctoral Student Shiri Shoob

 

“As early as 10-20 years before the appearance of the familiar symptoms of memory impairment and cognitive decline, physiological changes slowly and gradually occur within the patients’ brains,” explains the doctoral student who led the study, Shiri Shoob. “There is an accumulation of amyloid-beta deposits and abnormal accumulations of tau protein, a decrease in the volume of the hippocampus, and more. Moreover, about 30% of the people who were found to have a pathology typical of Alzheimer’s disease at postmortem did not develop the typical symptoms of the disease during their lifetime. It seems, then, that the brain has an, admittedly limited, ability to protect itself from the damage of the disease."

 

Uncovering Alzheimer's Protective Mechanisms

The research focused on finding those protective mechanisms that the brain has against the damage from the disease. The researchers found that during sleep - and especially during sleep as a result of general anesthesia - the early symptoms of Alzheimer’s disease, which appear many years before the symptoms of dementia, could be more easily identified. Prof. Inna Slutsky: “Anesthesia reveals pathophysiology in the brain activity in the animal model. We think that there are mechanisms that compensate for that same pathology while awake and thus prolong the pre-symptomatic period of the disease".

 

Prof. Inna Slutsky

Prof. Inna Slutsky

 

The researchers identified hyperactivity in the hippocampus - “silent seizures,” which look like an epileptic seizure in terms of brain activity, but do not appear externally - in in an animal model of Alzheimer’s disease.This, compared to the reduced activity in the healthy hippocampus during sleep and anesthesia. To examine potential treatment and prevention measures, the researchers tried a variety of methods, but mainly focused on deep brain stimulation (DBS) using electrical signals to the nucleus reuniens - a small nucleus in the brain that connects the affected hippocampus and the thalamus, which is responsible for sleep regulation.

 

“When we tried to stimulate the nucleus reuniens at high frequencies, as is done in the treatment of Parkinson’s, for example, we found that it worsened the damage to the hippocampus and the silent epileptic seizures,” said Shoob, “only after changing the stimulation pattern to a lower frequency were we able to suppress the seizures and prevent cognitive impairment. We showed that the nucleus reuniens could completely control these seizures. We could increase or decrease the seizures by stimulating it".

 

Decoding Alzheimer's

Prof. Slutsky adds: “Epidemiological studies indicate a link between aging and a phenomenon called POCD - cognitive problems that arise after surgery under general anesthesia. In young people, the symptoms usually pass very quickly, but in older people, the chance of cognitive impairment increases and it may last a long time. Our research indicates a potential mechanism underlying the phenomenon. We found that suppressing the thalamic nucleus reuniens - by pharmacological or electrical means - successfully prevented both pathological activity in the hippocampus during anesthesia and cognitive impairment following anesthesia.

In addition, we identified a relationship between certain pathological activity in the hippocampus during anesthesia in the presymptomatic phase of Alzheimer’s to memory problems in a more advanced stage of the disease. This indicates a potential for predicting the disease in the dormant state, before the onset of cognitive decline".

 

The leader of the study, Shiri Shoob, added: "We saw that no matter what means we used, when we inhibited the neural activity in the nucleus, we also measured a decrease in the pathological activity in the hippocampus during anesthesia".

 

The research was led by PhD student Shiri Shoob, with the participation of Nadav Buchbinder, PhD student Ortal Shinikamin, Halit Baeloha, Dr. Tomer Langberg, Dr. Daniel Zarhin, Dr. Ilana Shapira and Dr. Gabriella Braun from Prof. Inna Slutsky’s lab and in collaboration with Dr. Naomi Habib and Or Gold from the Hebrew University.
 

Left to right: Prof. Shlomi Reuveni, Ph.D. student Ofir Blumer & Dr. Barak Hirshberg

Research

Feb 12th, 2024
Could Restarting Change the Game for Chemical Research?

Not only in Information Technology: restart also works in chemical simulations

  • Exact Sciences

A new study from Tel Aviv University discovered that a common practice in Information Technology can also be applied in chemistry. Researchers found that to enhance the sampling in chemical simulations, all you need to do is stop and restart.  The research was led by Ph.D. student Ofir Blumer, in collaboration with Professor Shlomi Reuveni and Dr. Barak Hirshberg from the Sackler School of Chemistry at Tel Aviv University. The study was published in the journal Nature Communications.

 

If We Could Turn Back Time

The researchers explain that molecular dynamics simulations are like a virtual microscope. They track the motion of all atoms in chemical, physical, and biological systems such as proteins, liquids and crystals. They provide insights into various processes and have different technological applications, including drug design. However, these procedures can only depict events slower than one-millionth of a second, so they can't show slower processes like protein folding or crystal nucleation. This limitation, known as the timescale problem, is a great challenge in the field.

 

Ph.D. student Ofir Blumer: “In our new study we show that the timescale problem can be overcome by stochastic resetting of the simulations. It seems counterintuitive at first glance – how can the simulations end faster when restarted? Yet, it turns out that reaction times vary considerably between simulations. In some simulations, reactions occur rapidly, but other simulations get lost in intermediate states for long periods. Resetting prevents the simulations from getting stuck in such intermediates and shortens the average simulation time”.

 

 

The researchers also combined stochastic resetting with Metadynamics, a popular method to expedite the simulations of slow chemical processes. The combination allows greater acceleration than either method separately. Moreover, Metadynamics relies on prior knowledge. To speed up the simulation, it's essential to know the reaction coordinates. The combination of Metadynamics with resetting reduces the dependency on prior knowledge significantly, saving time for practitioners of the method. Finally, the researchers showed that the combination provides more accurate predictions of the rate of slow processes. The combined method was used to enhance simulations of a protein folding in water successfully and it is expected to be applied to more systems in the future. 

Research

Jan 30th, 2024
A Scientific Breakthrough That Will Help Increase Plant Yields in Dry Conditions

Using CRISPR technology, researchers succeed in growing tomatoes that consume less water without compromising yield

 

  • Life Sciences

A new discovery by Tel Aviv University has succeeded in cultivating and characterizing tomato varieties with higher water use efficiency without compromising yield. The researchers, employing CRISPR genetic editing technology, were able to grow tomatoes that consume less water while preserving yield, quality, and taste.

 

The research was conducted in the laboratories of Prof. Shaul Yalovsky and Dr. Nir Sade, and was led by a team of researchers from the School of Plant Sciences and Food Security at Tel Aviv University’s Wise Faculty of Life Sciences. The team included Dr. Mallikarjuna Rao Puli, a former postdoctoral fellow supervised by Prof. Yalovsky, and Purity Muchoki, a doctoral student jointly supervised by Prof. Yalovsky and Dr. Sade. Additional students and postdoctoral fellows from TAU’s School of Plant Sciences and Food Security, along with researchers from Ben Gurion University and the University of Oregon, also contributed to the research. The study’s findings were published in the academic journal PNAS.

 

The researchers explain that in light of global warming and the diminishing of freshwater resources, there is a growing demand for agricultural crops that consume less water without compromising yield. Naturally, at the same time, because agricultural crops rely on water to grow and develop, it is particularly challenging to identify suitable plant varieties.

 

In a process called transpiration, plants evaporate water from their leaves. Concurrently, carbon dioxide enters into the leaves, and is assimilated into sugar by photosynthesis, which also takes place in the leaves. These two processes — transpiration and carbon dioxide uptake — occur simultaneously through special openings in the surface of leaves called stomata. The stomata can open and close, serving as a mechanism through which plants regulate their water status.

 

The researchers highlight that under drought conditions, plants respond by closing their stomata, thereby reducing water loss by transpiration. The problem is that due to the inextricable coupling between the transpiration of the water and the uptake of carbon dioxide, the closing of the stomata leads to a reduction in the uptake of carbon dioxide by the plant. This decrease in carbon dioxide uptake leads to a decline in the production of sugar by photosynthesis. Since plants rely on the sugar generated in photosynthesis as a vital energy source, a reduction in this process adversely affects plant growth.

 

In crop plants, the decline in photosynthetic sugar production manifests as a decline in both the quantity and quality of the harvest. In tomatoes, for example, the damage to the crop is reflected in a decrease in the number of fruits, their weight, and the amount of sugar in each fruit. Fruits with lower sugar content are less tasty and less nutritious.

 

In the present study, the researchers induced a modification in the tomato through genetic editing using the CRISPR method, targeting a gene known as ROP9. The ROP proteins function as switches, toggling between an active or inactive state.

 

Prof. Yalovsky: “We discovered that eliminating ROP9 by the CRISPR technology cause a partial closure of the stomata. This effect is particularly pronounced during midday, when the rate of water loss from the plants in the transpiration process is at its highest. Conversely, in the morning and afternoon, when the transpiration rate is lower, there was no significant difference in the rate of water loss between the control plants and ROP9-modified plants. Because the stomata remained open in the morning and afternoon, the plants were able to uptake enough carbon dioxide, preventing any decline in sugar production by photosynthesis even during the afternoon hours, when the stomata were more closed in the ROP9-modified plants.”

 

To assess the impact of the impaired ROP9 on the crop, the researchers conducted an extensive field experiment involving hundreds of plants. The results revealed that although the ROP9-modified plants lose less water during the transpiration process, there is no adverse effect on photosynthesis, crop quantity, or quality (the amount of sugar in the fruits). Furthermore, the study identified a new and unexpected mechanism for regulating the opening and closing of the stomata, related to the level of oxidizing substances, known as reactive oxygen species, in the stomata. This discovery holds significant implications for basic scientific knowledge as well.

 

Dr. Sade: “There is great similarity between the ROP9 in tomatoes and ROP proteins found in other crop plants such as pepper, eggplant and wheat. Therefore, the discoveries detailed in our article could form the basis for the development of additional crop plants with enhanced water use efficiency, and for a deeper understanding of the mechanisms behind stomatal opening and closing.”


 

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