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.

Photosynthesis

To fully gain an insight into these interactions’ complexity, we must conduct an in-depth study and observation of the processes taking place. Initially, the sun’s released energy must be made useful to our body’s cells, for direct sunlight on its own is not useful. Energy from the sun, along with water from the soil and carbon dioxide released from all living organisms, synthesizes oxygen and sugars (including glucose) within the leaves of green plants. This seemingly simple but very complex process is called photosynthesis. Without the oxygen and glucose required to generate usable energy (in the form of ATP* molecules), no human or plant cells could survive, although some exceptions are known.(2) Hence, all photosynthetic organisms on Earth an indispensable sources of oxygen for all life-forms.

The two main sources of oxygen are rain forests and oceans, where green algae and photosynthetic bacteria live.(3) In fact, algae lying 120 meters beneath the Antarctic ice is fully equipped to serve life. These algae have been found in sponges with a system of fiber optics that allows them to gather the minute amount of light reaches the Antarctic Ocean’s murky depths and direct it to photosynthetic algae.(4) Given this, we must say that photosynthetic life-forms are in complete submission to and serve other life-forms, among them humanity.

Plant and tree leaves are optimally designed, both physically and biochemically, to generate vital oxygen and sugars. A leaf’s large surface area is required for the optimal interception of solar energy, while the thin cross-section is essential for the fast transport of oxygen and carbon dioxide in and out of the leaf.

Specific photosynthetic cells are arranged in between the leaf’s two protective epidermal layers. Carbon dioxide and oxygen molecules, under specific guidance, leave the leaf through specific pores flanked by cellular gates or guard cells situated underneath each leaf, as the leaf’s upper layer is covered with a protective waxy layer. This waxy layer is essential, for without it the leaf would dry up. For example, on hot days 100 gallons of water are lost from cottonwood trees.(5)

All evaporated water is collected as clouds (water vapor near the condensation point), from which pure, condensed water falls as rain. Likewise, all animals’ breath contains water vapor (released during the breakdown of glucose for energy release), which is also created as clouds and recruited as a moving source of potential water for all needy plants and living organisms.

Water’s continual recycling between the land and oceans to the clouds prevents wastage and provides a continually renewed source of fresh water to synthesize oxygen during photosynthesis. It also serves as a medium in which all biochemical reactions must take place in living cells.

Moreover, a leaf has no knowledge or power to generate oxygen and sugars, which are vital for all living cells, for it has never seen or experienced any direct contact. For carbon synthesis to occur, oxygen atoms must be torn from water and carbon dioxide molecules. This requires knowledge and power, since neither solar energy nor a leaf possess these. Also sugars, an indispensable food source for all life-forms, cannot be synthesized by coincidence in a weak and powerless leaf.

This complementary relationship indicates that all these simultaneous interconnections could only take place according to a program dictated through an all-pervading knowledge, willpower, and mercy. Likewise, only One with such attributes could subject, direct, and allowing these processes to continue.

Breathing

Moving at extremely high speeds (around 346m per second),(6) oxygen molecules released from such photosynthetic life-forms as plant and tree leaves, and bacteria and algae in the oceans, must reach the lungs of all living organisms. They also must be dissolved in water so that fish and other marine organisms can breathe. In fact, all of these processes must take place continuously so that each organism can live until its appointed time. This means that the oxygen molecules must be guided through the atmosphere and into each living organism so that each molecule’s optimal and perfect function may be carried out. Thus, although moving at extremely high speeds, each molecule’s function remains in the best and optimal manner.

Each lung is a highly delicate organ composed of millions of microscopic tunnels ending in tiny sacs (alveoli) encapsulated with a dense capillary (thin artery) network.(7) Oxygen molecules in the atmosphere are inhaled and brought to the sacs, which send oxygen (from within the sac) into the bloodstream, and carbon dioxide is diffused from the bloodstream into the sacs. Although the air we breathe contains a large proportion of nitrogen, it is mainly oxygen that is pulled through the sac’s wall, across the thin arterioles’ microscopic walls, and into the bloodstream’s red blood cells. Each oxygen molecule is then complexed and surrounded by a huge molecule of hemoglobin (the oxygen-carrying protein in red blood cells). Although these processes take place very quickly, every step occurs with exceptional precision and accuracy.

To reach the trillions of functionally different cells, the red blood cells must be pumped there with a great force. Therefore, all oxygenated red blood cells coming from the lungs are directed immediately to the heart. This masterpiece works continuously from birth until death, pumping fresh blood from the lungs to the tissues, and simultaneously pumps oxygen-deprived blood from the tissues to the lungs.(8)

Red blood cells flow through the arteries with great force. When they reach the thinnest arteries (capillaries) at tissues that are only one-cell thick, they almost align in a single queue within the capillaries and move carefully until the oxygen they carry is diffused to the surrounding needy tissue cells. At the same time, the waste gas of carbon dioxide is diffused quickly from the tissue cells into the blood plasma. The red blood cells then are directed into the veins, loaded with waste gas, and sent back to the heart (this requires great energy, as the blood returns to the heart at a very low pressure). From here, the oxygen-deprived red blood cells are pumped back to the lungs to be oxygenated. In the lungs, carbon dioxide is directed out to the sacs and exhaled into the atmosphere.

As creation contains no waste and every existence is useful, this waste gas is recaptured during photosynthesis to create vital oxygen, thereby displaying an unprecedented example of complementarity. Thus solar energy is harnessed to generate oxygen and provides a means of generating energy beneficial to cells (chemical energy). The oxygen created in this process is taken through multiple steps and stages until it is made available to the cells.

Conclusion

Here, we see a clear manifestation of perfect bounty and grace, for the cells needs are brought to them from afar and with extreme care after going through multiple ordered steps that easily could be disturbed. One insight we acquire is that each step takes place rapidly yet accurately, and so must require an infinite power and knowledge to occur.

We, Earth’s most intelligent creatures must admit our relative inability and impotence to understand fully or even to control any of these perfect processes. Rather than behave according to our vested interests and suppose Earth to be under our control, we should seek to understand our responsibility to know that all of these processes are somehow connected with us and subjected for our benefit in so many ways that conscious gratitude and faithfulness are required.

Footnotes

1. http://www.seds.org/nineplanets/nineplanets/sol.html.
2. Richard Monastersky, Deep Dwellers: Microbes Thrive far below Ground, Science News 151 (29 Mar. 1997):192-93.
3. http://gened.emc.maricopa.edu/bio/bio181/BIOBK/.
4. http://www.sciam.com/0297issuehttp://0297scicit3.html.
5. http://gened.emc.maricopa.edu/bio/bio181/BIOBK/.
6. http://fermi.bgsu.edu/~stoner/p201/idealg/tsld009.html.
7. http://biology/01.ux.com/MiraCosta/HumanResp.html.
8. http://www.atlcard.com/pump.html.