Abstract:

Bio-signalling transduction is one of the exciting fields in life sciences. There are variously physical and/or chemical modes for communication among organisms and their cells and organs. Actually, the environment is replete with chemicals, many of which have become part of a system of chemical communication. Chemical signals may operate on any of five levels of increasing complexity that correspond to cells, organs, organisms, groups and communities. It is unclear whether there is physically intraspecific or interspecific signals between plants. However, it was confirmed that plant can interpret and respond to secondary metabolites released by neighboring plants. Interplant chemical communication can occur among one species and another species of plant through air or soil media. Plant might warn each other about an imminent attack. The chemical recognition might occur between host and parasitic or associated plants. Methyl jasmonate(MJ) is a volatile chemical messenger that diffuses through the air from wounded plants, is potent in very small quantities, and starts a general signal cascade for increased production of defense chemicals in a wide range of plant families. Precursor of MJ is jamonic acid (JA), which occur in plant tissue and is also intercellular signal molecule in the systemic resistance of plants against herbivory. When interplant communication occurred through airborne signal, JA was converted to MJ, which is more volatile at room temperature, potentially allowing it to affect both remote parts of the releaser plant as well as nearly plants. More recently, other volatile chemicals implicated in plant to plant information transfer also were revealed. Methyl salicylate, ethylene and some α,β-unsaturated carbonyls have been reported for airborne plant to plant signals. Interplant chemical signals can also mediate through soil. The root-soil interface is a site where many interactions occur between plants and their environment. Some plants exuded chemical messengers by root tissue. A few chemicals from root exudates of host plant are germination stimulants and may be recognized by associated and parasitic plant. The seed of parasitic witchweed may be rapidly germinated by hydroquinone and sesquiterpene that respectively released from gramineous crops and cotton root tissues. Apigenin and cyclic xanthmine from legume root exudates were possible chemical messages through the root-soil interface. Nevertheless, it was difficult to capture and identify active chemicals from root tissues. As a result, interpretation of chemical signal on the root-soil interface has few progresses. In a word, the chemical messenger plays an important role in plant communication. Interpretation of the chemical signals among plants will be important scientific significance.

Key words: Plant, Chemical signal, Communication, Methyl jasmonate, Root exudates