Pleiotropic effects of tobacco-mosaic-virus movement protein on carbon metabolism in transgenic tobacco plants

Tissue-Specific Expression of the Tobacco Mosaic Virus Movement Protein in Transgenic Potato Plants Alters Plasmodesmal Function and Carbohydrate Partitioning

“…Pursuant to this assumption, transgenic plants in which plasmodesmata are modified provide an elegant system in which to further test the hypothesis that diffusion of SUC through plasmodesmata acts as a limiting step to symplasmic transport. Our comparative analysis of leaf photosynthetic performance, carbohydrate level, and carbon export in TMV-MP transgenic and control tobacco plants revealed a complex influence of the MP over these parameters (Lucas et al, 1993b;Olesinski et al, 1995). Fully expanded leaves of transgenic tobacco plants expressing the TMV-MP accumulated much higher levels of SUC, Glc, Fru, and starch during the day than did those of control plants.…”

“…Direct measurements of 14C-photosynthate translocation from source leaves indicated that export was lower in plants expressing the TMV-MP than in control plants (Olesinski et al, 1995). In addition to this effect on carbon allocation, the MP influenced the partitioning of dry matter between the various plant organs, resulting in a significantly higher shoot-to-root ratio (Balachandran et al, 1995).Analysis of carbohydrate levels and export rates from source leaves in transgenic plants expressing various TMV-MP mutants (Olesinski et al, 1995), combined with microinjection experiments in which plasmodesmal function was determined (Berna et al, 1991;Wolf et al, 1991), established that the TMV-MP has a pleiotropic effect on , 1996 leaf physiology. These findings suggested that the TMV-MP has at least two sites of action: one that modifies plasmodesmal SEL and another that affects carbohydrate metabolism and allocation (Balachandran et al, 1995;Olesinski et al, 1995;.…”

“…Fully expanded leaves of transgenic tobacco plants expressing the TMV-MP accumulated much higher levels of SUC, Glc, Fru, and starch during the day than did those of control plants. Direct measurements of 14C-photosynthate translocation from source leaves indicated that export was lower in plants expressing the TMV-MP than in control plants (Olesinski et al, 1995). In addition to this effect on carbon allocation, the MP influenced the partitioning of dry matter between the various plant organs, resulting in a significantly higher shoot-to-root ratio (Balachandran et al, 1995).…”

“…Analysis of carbohydrate levels and export rates from source leaves in transgenic plants expressing various TMV-MP mutants (Olesinski et al, 1995), combined with microinjection experiments in which plasmodesmal function was determined (Berna et al, 1991;Wolf et al, 1991), established that the TMV-MP has a pleiotropic effect on , 1996 leaf physiology. These findings suggested that the TMV-MP has at least two sites of action: one that modifies plasmodesmal SEL and another that affects carbohydrate metabolism and allocation (Balachandran et al, 1995;Olesinski et al, 1995;.…”

The release of genetically engineered micro‐organisms and viruses into the environment

“…Olesinski et al, 1995 ;Giddings et al, 1997). In bacterial mutants selected for novel phenotypes pleiotropy is common and is usually maladaptive, leading to reduced fitness .…”