Natural defence systems I. Elicitors

Plants have different methods of natural defence, Elicitors are one of them. The health of our lawns depends in many cases on the proper functioning of the two levels of natural defence that exist.

Against biotic attacks, referring to other living beings such as fungi, bacteria, viruses, insects, competition from other varieties, or abiotic attacks such as environmental factors such as extreme temperatures, drought, salinity, etc… These defences are activated by the perception of a signal that triggers the production of “elicitor” substances which, together with specific receptors, stimulate the natural defence processes.

Elicitors are substances that stimulate natural defence processes.

In most cases the signal is hydrogen peroxide, produced by the elimination of oxygen free radicals (very aggressive forms of oxygen for cells, caused by some kind of stress) through the enzymatic activity of peroxidases or superoxide dismutase.

Levels of natural defence:

• Active, thanks to its physical barriers (cuticle, cell wall, etc.) and its chemical barriers (terpenes, alkaloids, phenols, etc.).
• Passive, by activating its “Local Resistance” and “Systemic Resistance”.

The best known elicitor so far is phosphite (HPO3-2), which stimulates the formation of phytoalexins, substances related to terpenes, alkaloids, phenols and complex acids, with various antimicrobial functions. Phytoalexins formed by the action of phosphites have a specific effect on fungi of the Oomycete family (Phytophthora, Pythium…).

The use of products for natural resistance stimulation is essential for intelligent turf management.

In the last decade, there have been significant advances in new elicitors or activators of resistance induction, both in knowledge and in understanding and acceptance of their importance. Currently, research on the activation and repression of genes encoding disease and pathogen resistance proteins in turfgrass has led to the discovery of other elicitors, such as phenolics like Salicylic Acid (SA), oxylipins like Jasmonic Acid (JA) and other hormones like Ethylene (ET) and Abcisic Acid (ABA).

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The first level of stress response in our turfgrasses is local, involving the synthesis of phytoalexins, related to the increase of the enzyme phenylalanine ammonium lyase (PAL), its increase is related to increased resistance to viruses, bacteria, fungi and insects.

The next level of response involves systemic processes associated with the expression of defence PR genes (Hammerschimidt 1999) against fungi, bacteria, viruses or nematodes (Ryals et al 1996). Salicylic acid is involved in this level of systemic response (Mauch-Mani and Metraux 1998).

If you need more information on how to activate the natural defence systems of your greens, tees or pitches, please contact us at info@tiloom.com.

At Tiloom we have the most advanced natural resistance promoter products.