Survival of the fittest

Nature has its own rules and it plays its game on its own terms. If there is auto inhibition of spore germination, there is also infection court which requires minimum number of propagaules to cause the disease. If pathogen has to cause infection on a particular host , its the host which provides receptor molecules which are recognised by the pathogen and the host virtually invites pathogen to attack. Nature has compatible and incompatible response i.e. susceptible and resistant hosts to different pathogens. What induces resistance to pathogens- in biotrophic pathogens and necro-trophic pathogens ? Some times its absence of receptor molecules so that the pathogen is not able to attack as it is not able to recognise the host. It’s like you remove the name plate of your house and your guest is not able to locate your house. It is said that pathogenesis has evolved from symbiosis . Organisms which came as guests at first place became pathogens as they totally depended on their guests for space and nutrition. This was evolution of nature. Plants do not offer absolute resistance rather encourage pathogens to attack them and than train their metabolism to produce dynamic resistance. During biotic stress ( pathogen attack) or abiotic stress ( drought and salinity) certain proteins are unregulated and others are down regulated. Recent biotechnology is trying to obtain more and more information’s about gene action. However there are several hundred genes involved in defence mechanisms biotic or biotic resistance. There are some common mechanisms of resistance and gene expressions.