Interactions

Starting with the most basic of environmental interaction, as seen in the diagram to the right, Allium sativum is a photoautotroph which means it acquires it's food through a process known as photosynthesis. This is the process of combining water, sunlight, and carbon dioxide to create nutritional organic compounds for food. Oxygen is a pivotal byproduct of this process for all aerobic respiring organisms. Without autotrophs like garlic to deliver oxygen none of these organisms would survive. In terms of other plants, competition for vital resources are, for the most part, the extent of their interaction. Insects like bees and butterflies help to disperse pollen from plant to plant. Garlic's flowers attract these pollinating insects. When they go from one plant to another the pollen is spread, this creates higher genetic diversity and successful reproduction.

Like many other plants, garlic has a symbiotic interaction with a fungus known as mycorrize. A member of the phylum glomeromycota, mycorrize can be found in the roots of most vascular plants. The fungus is known to increase the surface area of the plant's roots allowing it to more efficiently acquire water and nutrients from the soil. This is a mutually beneficial relationship between the plant and fungus due to the sharing of acquired resources and the resulting increases in growth.

 Although, garlic plants have been known to ward off rabbits and moles(Wiki, 2012). In addition to humans, a wide range of pests and fungal pathogens are consumers of garlic. The most common of which are a variety of nematodes and several species of insects. Furthermore, diseases known as purple leaf blotch (Alternaria porri), pink root (Pyrenochaeta terrestris),white rot (Sclerotium cepivorum) ,and various viral pathogens are also associated with Allium sativum."Most garlic diseases are either soil- or seed-borne and usually can be controlled with proper sequence and planting disease-free seed"(Rosen et al, 2012). According to the PROTA database on Allium sativum(2005), "leaf blotch is very common when air humidity is high and when environmental factors, like poor calcium nutrition and aluminium toxicity, increase plant susceptibility". In agriculture, leaf blotch has been controlled with various fungicidal sprays(PROTAdatabase, 2005). Pink root, on the other hand is a soil borne disease, and it is normally kept under control by crop rotations with 5 years without onion and garlic(Rosen et al, 2012). Another disease known as "white rot (Sclerotium cepivorum) include symptoms of premature yellowing and dying of older leaves, stunting, and leaf tipburn, followed by destruction of the root system, shoot dieback, and rotting of the bulb." (Rosen et al, 2012). Viruses can also be found in many garlic strains, the most common of which are known as potyviruses or onion yellow dwarf virus (OYDV) and leek yellow stripe virus (LYSV) (PROTAdatabase, 2005). A variety of insects make up a significant body of garlic pests. For example, Thrips tabaci, commonly known as onion thrips are one of the most extensive garlic pests. They are sucking insects that cause symptoms of whitish specks on the leaves (De La Cruz and Garcia, 2007). According to Rosen et al, 2012, "Army worms are caterpillars who lay eggs in large fuzzy masses. The resulting larvae generally feed on the upper leaves of the garlic plant and move to a new plant after defoliation". Another species of insect pests are known as onion maggots.  Their white larvae can infect garlic plants. "Upon hatching, these maggots bore into the root system causing yellowing and wilting in young garlic plants" (Rosen et al, 2012). A similar parasite known as wireworms are yellow/brown beetle larvae that can damage the roots and bulbs of the plant (De La Cruz and Garcia, 2007). Perhaps the most important parasite of garlic, according to the PROTA database on Allium sativum, is a nematode known as the stem and bulb nematode. Usually it infects the stem tissues first, this results in stunting of the plants growth and the distinctive twisted and pale leaves that are symptoms of the infection. At the arrival of this stage of infection, rotting of the lower stem and base of the bulb occurs. Often times, entire fields can deliver deformed and dying young garlic plants (De La Cruz and Garcia, 2007). This is just an overview of some of the diseases and parasites associated with garlic. Agriculturally speaking, Allium sativum has a lot to contend with in its quest for adult hood.

Human Interaction

               On the other, perhaps more important side of interactions with garlic for humans, a vast amount of research suggests that Allium sativum holds promise in medicine across the board. Throughout history, human interactions with garlic have been subject to a positive spotlight. From the cloud of folklore surrounding garlic as an effective tool against black magic and its usual band of cronies to the real world health benefits in modern medicine. It is no wonder that garlic has been referred to in ancient writings from China, Egypt, Greece, and India (Milner, 1996). Historically we have seen garlic used in tea made to control colds, expectorant, diuretic, treatment of insect bites, headaches, and prevention of scurvy (Casey and Wynia, 2010).More recently, medicinal trials have provided evidence for the use of garlic in areas such as diabetes, food pathogen control, heart disease, and cancer prevention.

 For example, conclusions of several published research articles suggests positive results for the use of garlic in treatments for heart disease. One article examined individuals with hypertension. Unknown to the test subjects, half were given a placebo treatment and the others were given the garlic treatment. After repeated trials and analysis the researchers concluded that the individuals who received the garlic treatment, showed a significant decrease in average blood pressure during the course of the intervention compared to the placebo group. This could mean big things in heart disease research in the future.(Ried, Frank, and Stocks, 2008)

In addition, a study that explored the possible impact garlic has on diabetic individuals produced similar beneficial results. Using rats as the test subjects, garlic extract was administered several days prior to being induced with alloxan and several days after. The introduction of alloxan in rats is known to foster the development of diabetes and the rising of blood glucose levels characteristic of this condition. From the experiment the researchers concluded that when the garlic extract had been received several days prior to the alloxan, the uncontrollable increases in blood glucose were greatly reduced in most subjects.(Ojo, Memudu, Akintayo and Akpan, 2012)

Another article from the Journal of Applied Microbiology, looked at how Garlic (Allium sativum) performs as an inhibitor against common food pathogens. More specifically they performed an experiment using Staphylococcus aureus, Salmonella typhi, Escherichia coli and Listeria monocytogene as the sample pathogens. The researchers inoculated brain heart infusion broths with different concentrations of the sample pathogens and added varying concentrations of garlic extract. The observable data was collected from the measuring of the turbidity of the bacterial cultures through the use of a spectrophotometer. From the data collected in this experiment it was concluded that garlic can serve as  an effective inhibitor of these sample food pathogens. As a result of this effect, it was suspected that a component known as Allicin is responsible for the antimicrobial properties of garlic. This conclusion supports the use of garlic to increase shelf-life of food and limit the potential for food spoilage.(Kumar and Berwal, 1998)

In the hunt for advances in cancer research, garlic has proven valuable as well. The primary strategy employed in cancer research is identifying and understanding things called carcinogens. A carcinogen is a substance that is known to be directly involved in causing cancer. It does this by either having an ability to damage an organism's genome or somehow disrupt the metabolic processes of bodily cells. Results from several studies show evidence of anticarcinogenic potential as a dietary component for garlic derived compounds. This evidence includes a proven ability to prevent experimentally induced tumors in parts of the body like skin, mammary, and colon tissues. To the right is a table taken from the article that depicts these locations in the test subjects. This success was explained by a hypothesis about the general mechanism of action of dietary garlic compounds.  It showed changes in DNA repair performance and increases in the competence of the immune system. Overall it was concluded that the use of garlic as a dietary component could be useful in the prevention of a variety of cancerous tumors (Milner, 1996). Picking up where historical documentation of Allium sativum left off, you can see that modern research has further expanded on medical knowledge of garlic and highlighted the huge potential for further breakthroughs.