"One of the genes in the submergence gene cluster makes rice conserve the carbohydrate reserves in the plant leaves when the plant is submerged, resulting in a controlled growth for the plant," said Bailey-Serres, who is a member of UCR's Center for Plant Cell Biology. "Rice plants that lack this particular gene, however, are not able to conserve their carbohydrates. They end up with accelerated growth and ultimately exhaust themselves."
Flooding of croplands is a frequent natural disaster in many regions of the world, reducing crop productivity. While rice, the primary food for more than 3 billion people, thrives in standing water, it dies if it is completely submerged for more than four days. Water covering the rice plant reduces the plant's oxygen and carbon dioxide supplies, affecting photosynthesis and respiration. Submerged, the plants lack the gases needed to produce sugar for cellular energy, resulting in death if submergence persists beyond four days.
Bailey-Serres notes that access today to information about the rice genome ?all the genetic material in the chromosomes of rice ?has greatly accelerated progress in identifying specific genes that confer specific traits. "Currently, the International Rice Research Institute is actively crossing the submergence tolerant Indian rice with lines of rice that are widely grown in southeast Asia in order to produce new lines of rice that can grow in flood-prone areas," she said.
In the future, Bailey-Serres and colleagues plan to work on developing crops that are resistant to multiple stresses. "For example, we'd like to develop rice that is both submergence and salt tolerant," she said, "given that many flood-prone areas are a mixture of fresh and salt water."
Besides Bailey-Serres, Takeshi Fukao of UCR; and Kenong Xu and Pamela C. Ronald of UC Davis collaborated on the study, which was funded by grants from
Source:University of California - Riverside