|Enhancement of Osmotic
(Salinity) Stress Tolerance
in Rice - 98
Project Leader and Principal UC Investigators
Jan Dvorak, Professor, Department of Agronomy and Range Science, University of California, Davis
David Mackill, Research Geneticist, USDA-ARS, Department of Agronomy and Range Science, University of California, Davis
Sham Goyal, Specialist, Department of Agronomy and Range Science, University of California, Davis
Ming-Jun Gao, Visiting Scientist, Department of Agronomy and Range Science, University of California, Davis
Patrick J. Gulick, Professor, Concordia University, Montreal, Canada
Timothy J. Close, Associate Professor, Department of Plant Science, University of California, Riverside
|Concern over increasing salinity in
parts of the Sacramento Valley prompted this study into the basic biology of salt-stressed
rice. The aim is to develop an understanding of the cellular mechanisms that control
salinity tolerance in California rice and to target genes for the transgenic development
of salt-tolerant varieties.
High levels of dehydrin proteins have been observed in salt-stressed rice and other grasses. A detailed analysis of the genetic structure of the dehydrin protein family revealed that the production of dehydrins induced by salinity is controlled by a large number of genes. It is unlikely, therefore, that salinity tolerance could be dramatically improved by the incorporation of a single salinity tolerance gene from a highly salt-tolerant source like the wheatgrass Lophopyrum.
Salinity tolerance in rice and other cereals is also highly correlated with the exclusion of sodium and the maintenance of potassium in developing tissues and rapidly growing leaves. Researchers are searching for genes that control this physiological trait (K/Na selectivity) in rice and other grasses such as a salt-tolerant goatgrass. The ultimate goal is to isolate these genes and use them in the development of salinity tolerant transgenic rice.
In a parallel approach geared toward moderate enhancement of salinity tolerance, the rice germplasm collection is being screened to identify K/Na selectivity superior to existing California varieties. If successful, this germplasm would be used in marker-assisted breeding of improved salinity tolerance in California rice.