GENETIC EXPRESSION IN PROGENY OF TRANSGENIC PLANTS OBTAINED BY USING POLLEN-TUBE PATHWAY (OR DELIVERY) METHOD AND APPROACH TO THE TRANSFORMATION MECHANISM

The origin and the recent progress of pollen-tube pathway method (PTPM ) is described. The results of transforming wheat during 1990 to 1994 are reported briefly. They are: ( I ) Transformation frequencies were 3 %-6 %, even reached 13.5% : ( II ) the genetic expression of four co ntinuous generations obtained from single individuals of transgenic pl ants by self-fertilization was investigated. Plants with higher expres sion of foreign gene were found in every generation ( from T1 to T4 ), but a phenomenon of gene silence, in which the genotype contained for eign gene but did not express, was also observed. In addition, from th e angle of fertilization biology the transformation mechanism of PTPM (or PTDM) was analyzed and discussed. It was considered that the essen tial principle of this method was just like that of protoplast method.