GENETIC AND PHYSIOLOGICAL CHARACTERIZATION OF FLAVERIA-LINEARIS PLANTS HAVING A REDUCED ACTIVITY OF CYTOSOLIC FRUCTOSE-1,6-BISPHOSPHATASE

We investigated the genetic control of cytosolic fructose-1,6-bisphosp hatase (cytFBPase) activity, and the relationships between sucrose syn thesis capacity and photosynthesis, growth, flowering and whole-plant carbon partitioning in Flaveria linearis Lag. F-1, F-2, and selfed lin es generated from plants with low or high cytFBPase activity were used . CytFBPase activity was controlled by one gene and inherited co-domin antly, giving three classes of activity (low, intermediate and high). Reversed O-2 sensitivity of photosynthesis, which indicates an end-pro duct limitation on photosynthesis, was controlled by one gene and co-s egregated with low cytFBPase activity. A low activity of cytFBPase dec reased the growth rate. A recessive day-neutral flowering trait in Fla veria linearis did not co-segregate with cytFBPase activity. Plants wi th low cytFBPase activity had an increased shoot-to-root ratio, and fl owering caused an additional shift in carbon partitioning to shoots on ly in plants with low cytFBPase activity. These data indicate that alt ering sucrose synthesis can affect photosynthesis and plant growth and development.