Plant Immune Systems - GreenPassion.org - Dedicated to Medicinal Cannabis Cultivation and Education

The HSIC · #1 (**permalink**) 02-01-2008, 06:32 AM

An interesting read (v-man)

The world of plants and humans is a place of attack and defend, especially on the
microbial level, where tiny organisms are trying to use larger organisms as hosts and
food.

Human bodies defend themselves with two types of response when attacked by
pathogens. One response begins as soon as the body perceives a threat, such as a
wound that could introduce pathogens into the body. This is called the innate
immune system response.

After the innate immune system responds, usually by trying to prevent pathogens
from entering the blood stream to spread throughout the body, a more complex
“adaptive immune system” takes over. The adaptive immune system does more
than just isolate pathogens- it creates a total-body, coordinated response involving
antibodies and other tactics.

Plants also have an immune system that responds to harmful pathogens and insect
predators. Some of the pathogens that
plant immune systems counter are species of fungi. Marijuana plants are susceptible
to at least 100 species of fungi, including the dreaded botrytis cinerea, otherwise
known as gray mold, which can destroy an entire grow room’s ripe buds in 72
hours or less. Marijuana clones and seedlings are especially vulnerable
to pythium fungi that attack seeds before they sprout, emergent seedlings,
established seedlings, and clones. Another fungi species that plagues
cannabis is powdery mildew, which produces a white dust-like substance that
suffocates plant leaves while sucking nutrients out of the leaves. Marijuana
plants can be attacked by viruses, the most virulent of which is hemp streak
virus, and they are also susceptible to attacks by harmful bacteria.

When a marijuana plant is attacked by fungi, virus or bacteria, its innate
immune system engages the attackers. This system’s forward guard is a “sentry”
that senses invasive organisms inside and outside the plant. A receptor on the cell
membrane can detect the “legs” used for movement by pathogenic bacteria. Inside
the cell after pathogens are detected, chemical reactions carry signals that alert
the cell to danger. The cell then initiates a series of responses, some of which
notify other cells that the plant is under attack. Other responses, such as releasing
substances that alter pH or producing nitrous oxide and proteins, seek to destroy
the pathogen, but may also destroy the cell itself; scientists call this “programmed
cell death.”

The plant’s immune system guards against pathogenic invaders that colonize the
surface of stems and leaves, and it also fights parasitic insects. It is a highlyevolved
system, but it depends on its evolved ability to recognize threats and
the organisms that threaten cannabis are constantly evolving new forms, some of
which plant immune sentries are unable to detect.

If a pathogen is able to colonize inside or outside a plant without being detected by
the plant’s sentry systems, it’s likely that the invader will be able to take over the
plant, which will eventually destroy it. The use of chemical poisons, monocropping,
sea of green and other industrial agriculture techniques furthers the rapid
evolution and spread of pathogens and insects, and presents a major challenge
to cannabis growers. This same principal was at work in the case of avian flu,
which was created when factory farming put hundreds of thousands of chickens
together in Thailand in one small area where viruses could jump from bird to
bird, mutating to resist antibiotics as they were transmitted between each chicken.
If factory farming of meat and poultry did not exist, problems such as avian
flu and mad cow disease could not have developed and spread as they have.
Plant immune systems work with other plant systems to resist external threats,
such as pathogens, insects, drought, heat, and environmental toxins. As
with humans, a plant that is otherwise extremely healthy and facing no other
negative stresses in its environment will often be able to rise to defeat an acute
challenge from a solo pathogen. However, if marijuana plants are being grown in less
than optimum conditions, their immune systems and overall vigor are already
weakened, making it easier for pathogenic attacks to succeed.

Conditions that weaken a plant’s ability to defend itself include improper temperature
and humidity, inferior nutrition, inadequate lighting, incorrect light cycles,
lack of sanitation, biologically-inactive root zone, polluted water or air, plant
crowding, and other factors. The more of these factors that exist, the more stress the
plant is experiencing, and the less able it is to fight off pathogens and insects.

When a plant is attacked, it channels precious energy and resources to defeat
the invader. Programmed cell death and other immune responses can temporarily
force the plant to divert energy away from growth, maturation, flowering, and resin
production. This diversion can result in slow growth, delayed maturation, smaller
harvests, and less potent marijuana. Slow growth and delayed maturation are
often signs that plants are being attacked by pathogens, and can be useful signals
for pathogen detection even when more obvious symptoms of pathogenic activity,
such as the visual evidence of mold or mildew, are as yet absent.

If you are a conscientious, professional and diligent marijuana grower, you will
have designed your garden environment to minimize the risk of pathogenic infection.
This includes a thorough cleansing of the grow space prior to installation of
sterilized components. It includes use of extreme filtration that will remove
pathogens from air and water. It includes use of sterilized equipment, root media,
irrigation tubing and other components. Even with these precautions, and
especially in situations such as outdoor growing where total environmental
control is impossible, intelligent growers have begun to utilize a formula that acts
as a sort of vaccination for plants. When a vaccine is administered to
humans, it contains a tiny dose of pathogen that stimulates the human
immune system to prepare a pre-emptive immune response that gives the body
an advantage if the pathogen attacks the body en masse.

When a vaccine is administered to plants, it does not contain tiny doses of fungi,
but it does contain components that stimulate plant immune systems. When
plant immune systems are stimulated in this subtle, pre-emptive manner, they can
respond more quickly to create internal or external responses that ward off pathogens
and insect pests.

Indeed, some veteran marijuana growers believe that “stressing” a plant creates an
immune system response that produces more resin, which is often believed to
be produced as a means of repelling or immobilizing insects. In the 1960’s and
70’s, for example, Latin American growers of classic varieties such as Colombian
Gold and Panama Red would pound small nails into the stalks of their plants, hang
rocks from their branches, underwater them, or shake them violently, all in hopes
of inducing a stress response that would make plants produce more potent resin.
Marijuana horticultural product companies tend to approach pathogens and insects
by offering modified and supposedly lesstoxic versions of pesticides and fungicides
containing natural products instead of chemicals. The safety of some of these
products when used in floral phase is uncertain, and the efficacy of such
products is doubtful.

Seeking an alternative to the ill-advised use of external chemical sprays or
devices such as sulfur burners, scientists at a Canadian company called Advanced
Nutrients discovered how to create a vaccination for plants. Their goal was
to create “induced systemic resistance” to disease, pests, and other threats. The
product they created, called Scorpion Juice, uses several key components to
stimulate a pre-emptive immune response in marijuana.

During the design phase of Scorpion Juice, their scientists noted the similarities
between plant responses to attacks and human responses. When a human is
invaded by viruses, harmful bacteria or other pathogens, the body reacts with
fever, swelling, redness, inflammation and other responses. When pathogens or
insects attacks plants, plants respond using some of the same methods, such as lesions
on leaves, loss of leaves, and the release of cell to cell chemical signalers that place the
entire plant on alert against the invaders. During their research, the scientists found
the vital role that a naturally-occurring form of aspirin plays in plant immune
system function. Drug store aspirin is actually a chemical analog of this natural
form of aspirin. The chemical analog was created by the Bayer Corporation in
1859, based on a natural material found in willow bark and other plants, known
as “salicylic acid.” Bayer’s aspirin is acetylsalicylic acid.

Salicylic acid is found in many plants and trees, and is believed to be a first line
of defense against pathogens and other invaders. Plants release a large amount of
salicylic acid when they are attacked by pathogens; this corresponds to subsequent
releases of other plant proteins that also appear to promote plant survival.
Studies show that plants treated with salicylic acid became extraordinarily
resistant to powdery mildew, which is one of the most persistent plant diseases that
affect marijuana.

One Cornell University study found a protein and gene pair (salicylic acidbinding
protein 2- SABP2- and its gene) that facilitates inner-plant communication
that is believed responsible for increased plant immune system response. The
Cornell researchers said that using immune system enhancement rather than
pesticides, herbicides and other protective measures was a safer way of helping ag
crops battle threats.

In studies involving tobacco mosaic virus, which has been known to attack a
variety of plant crops including cannabis, scientists found that SABP2 triggered
release of salicylic acid, which then created a “hypersensitive resistance
response” that included programmed cell death at the site of the attack as plant
cells sacrificed themselves for the overall survival of the plant. The cell death
isolated the attacking organism so that it could not spread throughout the plant.
Using natural formulas on roots and leaves to create induced systemic resistance is
a delicate art. It is the same when using vaccines to inoculate humans against
disease. Some humans will develop symptoms of a disease after they have
been given a vaccination for the disease. Their bodies were unable to handle the
small amounts of pathogenic material that the vaccination infused into them.
Similarly, growers using products such as Scorpion Juice should closely monitor
their plants to ensure that the proper amount of immune stimulation is taking
place. Too much stimulation can slow growth and divert energy from floral
production. The proper amount of immune stimulation, combined with nutritional
support such as silica, vitamin, and enzyme augmentation, gives marijuana
plants an enhanced immune response that gives them a much better chance
of surviving pathogenic attack and also increases metabolism and vigor, which
results in higher yield and potency.