In vivo detection of agrobacterium virulence gene expression inside monocotyledonous and dicotyledonous plants

摘要

Monocotyledonous plants, especially economically important gramineous crops, are more recalcitrant to Agrobacterium-mediated transformation than dicot plants. The molecular basis for this phenomenon is not well established although Agrobacterium virulence (vir) genes responsible for the transformation process have been cloned and well characterized. Some of plant signal molecules that can induce the vir gene expression have also been identified and studied with in vitro systems using plant extracts, which however differ from the plant environment that the bacteria encounter during the infection. In addition, it is known that plant tissues may produce compounds that can inhibit the vir gene expression. To monitor the in vivo vir gene expression inside plant tissues, we used a promoter-less gene encoding a green fluorescent protein (GFP) as reporter system to construct vir-gfp fusions, as the fluorescence is an intrinsic property of the protein and can be readily detected. We used wheat and maize plants to represent monocots and tobacco plant to represent dicots. We found that the Agrobacterium vir gene expression inside monocots was weaker than that inside dicots.