Effectors and Hormones
Effectors and hormones are other signalling molecules often confused with elicitors. Elicitors and effectors differ from hormones in that they are not produced within the organism that they are triggering a response in, and are usually not naturally occurring in the organism.Plant Hormones
Effectors
Effectors are proteins secreted by microbial pathogens which can either trigger or compromise immunity depending on the ability of perception (presence of suitable receptor) and response (appropriate defence reaction) of the plant. Effector could be extracellular or injected directly into cells. Microorganisms are able to inject effectors directly into host cells to by-pass induced defences in plants. This compromises the host plant's defence system and is referred to as effector-triggered susceptibility (ETS). The remaining immunity is called basal defense which can limit the spread of virulent pathogens in their hosts but it is typically insufficient to prevent disease. In response to this threat, plant's have evolved effector recognition protein receptors to recognise, or monitor, effectors and initiate effector-triggered immunity (ETI).{{Cite journal, title = Plant Immune Responses Against Viruses: How Does a Virus Cause Disease?, journal = The Plant Cell, date = 2013-05-01, issn = 1040-4651, pmid = 23709626, pages = 1489–1505, volume = 25, issue = 5, doi = 10.1105/tpc.113.111658, first1 = Kranthi K., last1 = Mandadi, first2 = Karen-Beth G., last2 = Scholthof, pmc=3694688 ETI is a strong immune response that efficiently protects plants from avirulent biotrophic pathogens and is often associated with the hypersensitive reaction (HR), a form of programmed death of plant cells at infection sites.Crop Protection and Commercialisation of Elicitors
Elicitors can protect crops from diseases, stress and damage. Elicitors do not need to be directly toxic for pathogenic organisms or pests to be of benefit. Therefore, they are an alternative to conventional pesticides which are often harmful for the environment, farmers and consumers and for which consumers are increasingly seeking safer alternatives.References