Affects of Exudates on Plant Communications

The roles exudate root secretions play in the communication and interaction of plants is a wide and varied area of study. These exudates can be used as a type of defense against other plants and in this form act allopathically. They inhibit the growth, establishment and affect survival rates of neighboring competing plants and root systems and therefore defend against their resources being taken away (Bais et al 2006).

The compounds in which plants use to defend themselves are usually in the form of phytotoxins but these vary considerably in composition and function between plants. Exudates need to be at certain concentration if they are to affect the growth of neighboring plants. Plants such as Centaurea maculosa and C. diffusa produce their phytotoxins in high concentrations. These phytotoxins can often work in the favor of invasive weeds species as in their new environment the native plants may have never encountered their damaging exudates and therefore no forms of resistances have evolved. This then gives the weeds an upper hand in taking over these environments and expanding their distribution. The sensitivity of native plants to unknown phytotoxins may also explain why invasive species haves such success in new environments (Bais et al 2006).

Exudates do not only serve as a purpose in plant defense interactions but also have use for positive plant to plant interactions. Although these positive interaction are less frequently documented some root exudates increase herbivore resistance in neighboring plants which is highly fascinating because it gives a sense of altruism in plants communities. This is highly debated as it is assumed that in the natural world organism are generally in competition with each other (Bais et al 2006).

Reference

Bais H. P., Weir T. L., Perry L. G., Gilroy S. and Vivanco J. M. (2006) THE ROLE OF ROOT EXUDATES IN RHIZOSPHERE INTERACTIONS WITH PLANTS AND OTHER ORGANISMS, Annual review of Plant Biology 57.  233-266p