OVEREXPRESSION OF FLAVODOXIN IN ALFALFA NODULES LEADS TO DELAYED SENESCENCE AND HIGH STARCH ACCUMULATION

摘要

Nodule senescence is the sequence of structural, molecular, biochemical and physiological events leading to the loss of the nitrogen-fixing activity and to cell death in the symbiotic tissue. A senescence-inducing signal from the plant causes a decrease in antioxidant levels and, thus, an increase in reactive oxygen species (ROS) up to a point of no return (Puppo et al., 2005). Nitrogen fixation is very sensitive to ROS and nitro-genase activity drastically decreases during nodule senescence. Delayednodule senescence represents a strategy that could lead to increased nitrogen fixation and legume productivity. Delayed nodule senescence together with amelioration of sustainability under field conditions constitutes a key aim of legume improvement programs (Puppo et al., 2005).