Agrobacterial Transformation of Uninjured Plants

The capacity for agrobacterial transformation (using Agrobacterium tumefaciens strain GV3101 with the activated vir genes) was investigated in uninjured seedlings of tobacco (Nicotiana tabacum L.), rice (Oryza sativa L.), and wheat (Triticum aestivum L.) along with the effect of various factors on the frequency of tobacco seedling transformation. Transformed cells were found at the base of the rice leaf sheath and in the upper part of tobacco leaves, whereas they were absent from wheat leaves. Illumination and temperature, which were below and over the optimum, were the factors limiting agrobacterial transformation of uninjured plants. Preincubation of tobacco seedlings in 100 M ABA, 10 mM EGTA, and 0.1 mM colchicine decreased the frequency of agrobacterial T-DNA penetration into plant cells. The authors conclude that transformation occurs predominantly in young growing cells, and its frequency is related to the state of stomata and plasmodesmata of the target plant cells. The elements of the cytoskeleton probably participate in T-complex transport.