Potato plants were treated with signal molecules SA,MJ,ETH and ABA.The leaves were sampled at different time points and the total RNA was extracted for semi-RT-PCR analysis.The relative expressions of Star gene under the four signal molecules were analyzed.The results showed that Star gene could be rapidly induced by SA,MJ and ABA but slowly by ETH.The expressions of Star gene induced by the four signal molecules were widely overlapped,suggesting that this gene could take part in a very important process of signal transmission in response to Phytophthora infestans infest.