Agrochemical control of plant water use via engineered abscisic acid receptors
Park et al. Nature, February 2015.

A recent breakthrough study reported that scientists successfully engineered drought-tolerant plants by adding a new piece of DNA to their genomes. Crops and many types of plants are increasingly challenged by hostile environmental conditions such as globally warming temperatures and diminishing water sources. Plants have very small openings called “stomata” that let carbon dioxide in and oxygen out. Each stoma is surrounded by two guard cells that control opening and closing using osmotic pressure. During daytime, the stomata lets plants allow carbon dioxide in and oxygen out. Since the air around the leaves is often drier than inside, water molecules also move out through the stomata – a process called transpiration. Under the stress of drought, plants produce a hormone called abscisic acid (ABA). When ABA is released, it makes guard cells close the stomata and in turn keeps the plant from losing the water. Scientists previously thought that if they could spray ABA on a whole field, plants would survive a drought. However, since ABA is very expensive and highly sensitive to light, this strategy never became an option. Then, scientists decided to take the commonly used fungicide mandipropamid and genetically engineered the plants to respond to mandipropamid as if it were ABA. By adding a new piece of DNA into genomes, plants ended up having slightly different ABA receptors, which can be efficiently activated by mandipropamid.  Researchers tried this approach on two different plants: tomatoes and Arabidopsis. When mandipropamid was sprayed, genetically engineered plants stopped transpiration, and hence were able to survive for 12 days without water. The next challenge is to test this strategy in real world crops. This approach potentially opens new avenues for crop improvement that could highly benefit a growing world population.

3D Vaccines to Cure the Cancer

Injectable, spontaneously assembling, inorganic scaffolds modulate immune cells in vivo and increase vaccine efficacy
Kim J et al. Nature Biotechnology, December 2014.

Cancer is a devastating disease.  The World Health Organization (WHO) predicts that global cancer incidence rates will grow by nearly 60% to 22 million cases per year over the next two decades. The effective cure for cancer has not been developed yet, mostly due to its ability to escape the body’s immune system. Unlike infectious reagents like bacteria and viruses, cancer cells are actually our own cells that are broken and misplaced; they cause trouble as they grow. Scientists have been trying hard to develop vaccines that activate the immune system to recognize tumor cells as foreign and attack them. In a recent study, scientists reported that they designed a “3D vaccine” to effectively provoke the immune system to fight cancer. The 3D vaccine is composed of many microsized, porous silica rods submersed in liquid, where any combination of tumor antigens and immune-stimulating reagents can be loaded into.  Once the 3D vaccine is injected under the skin, it forms into a dime-sized scaffold that creates an “infection-mimicking microenvironment.” The scaffold then attracts the dendritic cells that patrol the body for harmful pathogens. When the scaffold was tested in mice, it showed over a 90% survival rate in animals that would normally die from lymphoma within 25 days. Further analyses in mice showed that the 3D vaccine can recruit, house, and manipulate immune cells to initiate a powerful immune response against cancer. As much as the discovery is promising, one should keep in mind that much more evidence will be required to establish 3D vaccines as a feasible way of combating human cancer.

Smoking Shrinks the Brain

Cigarette smoking and thinning of the brain’s cortex
Karama S et al. Molecular Psychiatry, February 2015.

Smoking is regarded as the single most preventable cause of disease, disability, and death. Past studies strongly linked smoking to cancer and lung diseases. A recent study now shows that smokers have a thinner brain cortex than non-smokers. The cortex is the outer brain layer in which critical cognitive functions such as memory, language, and perception take place. It is well known that the cortex becomes thinner with normal aging and cortical thinning is associated with cognitive decline and dementia. The study found that smoking accelerates this thinning process. Researchers analyzed brain MRI scans of 244 males and 260 females with an average age of 73, around half of whom were former or current smokers. Participants who had given up smoking for the longest time had a thicker cortex compared with those who had given up recently. Researchers cautiously suggest that the cortex might regain some thickness once smokers quit but the recovery is very slow and incomplete. For example, heavy smokers who had quit more than 25 years before still had a thinner cortex.

New Jersey-based Helping Hands Relief Foundation (HHRF) is one of those relief organizations that have quickly responded to the call for help from the Horn of Africa. Many volunteers of HHRF have already taken off to Somalia to deliver donations and food to the victims.

The world is undergoing several major tests. The problems caused by economic crises one after another, terrorism, global warming, and others have to be tackled with immediately. But the emergency of the current famine has no comparison, and we have to act now. It is time to delay our own needs today and rush for help to the victims of the famine. This is the greatest test we as the human family have to be pass.

Resurrection plants are desiccation (extreme dryness) tolerant plant species. All are relatively small and mostly found in Southern Africa, North America, Brazil, and Australia. They are able to stay in a dehydrated state under conditions in which other plants would perish. They come back to life and resume their physiological activities when water becomes available again. During the dehydration process, leaves of resurrection plants shrink and curl up due to water loss. Some of them fold up their stems into a tight ball as they desiccate to limit surface area and conserve internal moisture. It is not yet clear how the leaves and stems reduce their size. However, electron microscopy revealed desiccation-induced cell wall folding in the majority of mesophyll and epidermal cells of a resurrection plant. Thick-walled vascular tissue did not fold and supported the surrounding tissue, thereby limiting the extent of leaf shrinkage and allowing leaf morphology to be rapidly regained upon rehydration (Moore et al 2006, 651–62). When the resurrection plant is dehydrated, its stomatal conductance and intercellular CO2 concentration is decreased and hence its photosynthetic rate, but sugar, starch and non-structural carbohydrate reserves increased during this stage. Mature tissues of resurrection plants such as leaves and roots are able to remain in the air-dried state for months by reaching an inactive state, comparable to dormancy in seeds in several aspects. All metabolic functions are reduced to a bare minimum and they appear to be dead. Resurrection plants take immediate advantage of rainfall after dry periods: they absorb water, grow rapidly, and reproduce (Bartels 2005, 696–701; Xu 2010, 183–190).

One of the most common examples of resurrection plants is Myrothamnus flabellifolia, grown in southern Africa, the only known woody resurrection plant. Craterostigma wilmsii and Xerophyta viscosa are other resurrection plants from southern Africa. All these plants are used extensively in African medicine and traditional culture. Ramonda serbica and her sister Haberlea rhodopensis are members of Gesneriaceae family from the Balkan peninsula; they are rare and forbidden for collecting. Anastatica hierochuntica is native to western Asia, while Selaginella lepidophylla is collected from the wilderness of the southwestern United States and Mexico, sold to tourists, and exported worldwide—it can even be bought online, in their dry and lifeless form. After buying this plant, we soak it in water and voila! If one does not have a “green thumb” and still want to have greenery in one’s home, this resurrection plant might work best for you. However, its downside is that sometimes people complain that the gray-brown ball and its branches do not become fully green or open up in water totally, which does not look very attractive. But even though you may not like how it looks, your kids might enjoy it as a science project.

Why is it important to know how these plants survive drought and come back to life?

The world’s need for water is likely to become one of the most critical resource issues of this century. The International Water Management Institute predicts that by the year 2025, one-third of the world’s population will reside in regions that experience severe water scarcity (www.iwmi.org) (Bartels and Salamini 2001, 1346–1353). Drought is a factor that dramatically threatens the world’s food supply. Therefore, plant scientists have been interested in using resurrection plants as model organisms to find out noble cellular mechanisms for improving the drought tolerance of important crop plants. Research on the molecular genetic mechanisms, metabolic and antioxidant systems as well as macromolecular and structural stabilizing processes in resurrection plants have been carried out (Moore et al 2009, 110–7). One study of Craterostigma wilmsii demonstrates that it relies almost entirely on protection during natural drying; however, it also induces a repair mechanism during rehydration that enables recovery from rapid drying. Thus, it apparently has the ability to repair if protection is inadequate and damage is incurred (Cooper 2002, 1805–13). In addition to repair mechanisms of resurrection plants, the processes that involve regulation of gene and protein activity that allow these plants to use energy storage efficiently have been investigated. The resurrection capability appears to be associated with the accumulation of a carbohydrate in the tissues as they dry. In a majority of cases, sucrose is the major carbohydrate that accumulates (Norwood et al. 2000, 159–65). In addition, an unusual disaccharide named trehalose, which is the main blood sugar in insects and serves as a major energy storage molecule enabling flight, is found in high levels in resurrection plants. This is unusual, because normally there is not much trehalose in plants. It has been proposed that trehalose serves as an osmoprotectant (Avonce et al 2005, 276–279). Osmoprotectants are small molecules that help organisms to survive when a rapid change in the movement of water across their cell membrane occurs. Peter Scott of the Annuals of Botany wrote a summary of the ability of resurrection plant Craterostigma plantagineum to survive dehydration and revive (Scott 2000, 159–166). According to his botanical briefing the roots, being in the soil, are most likely to sense the decrease in water availability first. Abscisic Acid (ABA), a plant hormone, is synthesized and released by roots as a response to drought stress. Once released, ABA could activate batteries of genes required for metabolic processes such as the accumulation of sucrose from either stored carbohydrates or through an alteration in photosynthetic carbon partitioning. In addition, the synthesis of other proteins such as dehydrins and Late Embryogenesis Abundant proteins (LEAs) could help to stabilize the plant cells as they lose water. Thus as the tissues dehydrate, leaves shrink, chlorophyll is degraded, sucrose accumulates and ultimately the xylem, which is one of the transport tissues in plants, fills with air and the plants become desiccated. On addition of water, the xylem refills with water and cells begin to take up water and expand, enzymes present in the tissues are activated, sucrose is metabolized, and chlorophyll is resynthesized. Within 24 hours the plant is restored, and is reproductively active within two weeks.

Based on these findings, it is of particular significance to understand the cellular and molecular mechanisms of resurrection plants and focus on biological engineering strategies for improving plant drought tolerance in important crop species such as cotton, soybeans, peanuts, corn, and potatoes. But these plants do not merely represent a unique model for scientists to understand a plant’s ability to cope with drought; they also serve us to deepen our faith for the Day of Judgment and rationalize it in our minds. The astonishing changes in the tissue of resurrection plants, and how they are brought back to life when they appear to be completely dead, remind us of Qur’anic verses such as the one below regarding the resurrection of decayed flesh and bones (36:78–79).

“And he puts forth for Us a parable, and forgets his own creation. He says: ‘Who will give life to these bones when they have rotted away and became dust?’ Say: ‘He will give life to them Who created them for the first time! And He is the All-Knower of every creation!’”

Time-lapse videos of resurrection plants in action, like Xerophyta and Jericho rose, are available on the web. Enjoy!

References

• Moore JP, Nguema-Ona E, Chevalier L, Lindsey GG, Brandt WF, Lerouge P, Farrant JM, Driouich A. 2006. Response of the leaf cell wall to desiccation in the resurrection plant Myrothamnus flabellifolius. Plant Physiol. 141:651–62.
• Bartels D. 2005. Desiccation Tolerance Studied in the Resurrection Plant Craterostigma plantagineum. Integr. Comp. Biol. 45: 696–701
• Xu D, Su P, Zhang R, Li H, Zhao L, Wang G. 2010. Photosynthetic parameters and carbon reserves of a resurrection plant Reaumuria soongorica during dehydration and rehydration. Plant Growth Reg. 60: 183–190.
• http://faculty.ucc.edu/biology-ombrello/pow/resurrection_plant.htm
• Bartels D, Salamini F. 2001. Desiccation tolerance in the resurrection plant Craterostigma plantagineum. A contribution to the study of drought tolerance at the molecular level. Plant Physiol. 127:1346–1353.
• Moore JP, Le NT, Brandt WF, Driouich A, Farrant JM. 2009 Towards a systems-based understanding of plant desiccation tolerance. Trends Plant Sci. 14:110–7.
• Cooper K, Farrant JM. 2002. Recovery of the resurrection plant Craterostigma wilmsii from desiccation: protection versus repair. J Exp Bot. 53:1805–13.
• Norwood M, Truesdale MR, Richter A, Scott P. 2000. Photosynthetic carbohydrate metabolism in the resurrection plant Craterostigma plantagineum. J Exp Bot. 51:159–65.
• Avonce N, Leyman B, Thevelein J, Iturriaga G. 2005. Trehalose metabolism and glucose sensing in plants. Biochem Soc Trans. 33:276–279.
• Scott P. 2000. Resurrection Plants and the Secrets of Eternal Leaf Annals of Botany. 85: 159–166.