THE EFFECT OF TEMPERATURE ON AGROBACTERIUM-TUMEFACIENS-MEDIATED GENE-TRANSFER TO PLANTS

Agrobacterium tumefaciens is generally used to achieve genetic transfo rmation of plants. The temperatures that have been used for infection with Agrobacterium in published transformation protocols differ widely and, to our knowledge, the effect of temperature on the efficiency of T-DNA transfer to plants has not been investigated systematically. Ag robacterium tumefaciens strains harbouring a binary vector with the be ta-glucuronidase (uidA) gene and either a nopaline-, an octopine- or a n agropine/succinamopine-type helper plasmid were tested in two transf ormation systems at temperatures between 15 and 29 degrees C. One syst em involved cocultivation of Phaseolus acutifolius callus whereas in t he other system Nicotiana tabacum leaves were vacuum-infiltrated. In b oth situations, irrespective of the type of helper plasmid, the levels of transient uidA expression decreased notably when the temperature w as raised above 22 degrees C. Expression was low at 27 degrees C and u ndetectable at 29 degrees C. We anticipate that the efficiency of many published transformation protocols can be improved by reconsidering t he factor of temperature.