2005 Annual Report 1.What major problem or issue is being resolved and how are you resolving it (summarize project aims and objectives)? How serious is the problem? What does it matter? While salinity is one of many environmental factors resulting in suboptimal crop yield, its impact is one of the most far-reaching in agronomic terms. Unlike most toxins or herbicides, salinity has no specific cellular target. Thus, most of the early work on salinity focused on the manifestations of salt-stress. The exact physiological, biochemical, molecular biological, and biophysical mechanisms remain unresolved. The thrust of this research is to identify the array of cellular, biochemical and physiological mechanisms utilized by the plant to adapt to saline environments so that a rational basis may be formed for the development of salt-tolerant plants. Because of increases in global population, world agriculture must produce a greater yield per unit area than ever before. However, worldwide one-half of all irrigated lands are seriously affected by salinity or water logging. Currently, more land is not being irrigated due to salinity problems than there is new land coming under irrigation. It is believed that in the past soil salinity has contributed to the decline of several ancient civilizations. Irrigated agriculture takes on a special importance in this regard as it has a high yield per unit area and is less dependent on the uncertainties of weather. Furthermore, high-quality water needed for agriculture is becoming increasingly scarce due to changing environmental standards and rising demands from urban areas. The research falls under National Program 201, Water Quality and Management and contributes to National Program 302, Plant Biological and Molecular Processes. 2.List the milestones (indicators of progress) from your Project Plan. Milestone 1 (FY 2004) Relation of physiological characters to salinity tolerance in grain crops: Initiate greenhouse experiments with rice to investigate the interrelationships among individual physiological characters, ion uptake and accumulation, growth and yield. Identify appropriate stages of growth when specific characters and their interrelationships are best determined. Heritability and selection: Introduce Recombinant Inbreeding Lines from the International Rice Research Institute, The Philippines. Increase seed under stringent quarantine protocol. Begin first selection of plants based on ion content and ion selectivity. Milestone 2 (FY 2005) Relation of physiological characters to salinity tolerance in grain crops: Initiate greenhouse experiments with wheat to investigate the interrelationships among individual physiological characters, ion uptake and accumulation, growth and yield. Identify appropriate stages of growth when specific characters and their interrelationships are best determined. Relation of physiological characters to salinity tolerance in grain crops: Analyze/evaluate results of rice study. Complete greenhouse wheat experiment. Heritability and selection: Complete first selection of RILs based on ion content and ion selectivity. Mapping of ion selectivity in rice: Extract DNA for PCR marker screening by Dr. Tai (U.C. Davis). Screen RILs and backcross populations for PCR markers at Davis and Riverside. Milestone 3 (FY 2006) Field studies (first year): Construct specially designed facilities for paddy fields using aluminum rings at Davis. Grow plants, analyze physiological characters, and compare data with greenhouse results. Develop rice growth model that incorporates physiological characters, ion selectivity, and stage of plant growth. Heritability and selection: Complete second selection on ion contents and ion selectivity in genetic populations. Determine realized heritability using ion selectivity as selection criterion. Mapping of ion selectivity in rice: Continue analyzing genotypes of SSR using MapQTL for QTLs controlling ion uptake in rice. Field selection (first year) using the QTLs identified by molecular markers. Milestone 4 (FY 2007) Field studies (second year): Complete field trials and analyze physiological characters. Heritability and selection: Conduct field trials of the selected RILs and backcross families at Biggs, California. Mapping of ion selectivity in rice: Complete field selection (second year) using the QTLs identified by molecular markers. Milestone Time Line. Publication and presentation of results will occur as significant outcomes arise. 4a.What was the single most significant accomplishment this past year? What were the most significant accomplishments this past year? Gene expression under salinity stress Identification of genetic variation for salt tolerance is necessary for plant breeders to develop more salt tolerant varieties. In cooperation with Drs. Timothy J. Close, UC Riverside, and Abdelbagi Ismail, International Rice Research Institute, the Philippines, ARS scientists at the George E. Brown, Jr. Salinity Laboratory exploited the recent completion of the rice genome sequence (2004) and the enhanced annotations of the rice genome (TIGR rice pseudomolecules, release 3; www.tigr.org/tdb/e2kl/osa1) by using the whole genome microarray from Affymetrix to identify genetic variation at the transcriptional level. Our study focused on two indica rice genotypes, FL478, a salt-tolerant recombinant inbred line (RIL), and IR29, the salt-sensitive parent. The response of the sensitive genotype, IR29, was characterized by induction of a relatively large number of probe sets compared to tolerant FL478. Additionally, salinity stress induced a number of genes involved in flavonoid biosynthesis in IR29 and cell-wall restructuring in both IR29 and FL478. This information can impact plant breeding and serve as a rational basis for the development of salt-tolerant plants. 4b.List other significant accomplishments, if any. Physiological parameters involved in salinity tolerance In order or plant breeders to select for salt tolerance at early growth stages, it is useful to identify the relationships between physiological parameters and growth performance of seedlings. Plants of 31 genotypes were grown in sand tanks to study the effect of salinity on the physiological parameters such as sodium (Na), potassium (K), and calcium (Ca) uptake, K-Na selectivity, Na-Ca selectivity, and growth performance characters such as tiller number, leaf area, plant height, and shoot dry weight. Ward’s minimum-variance cluster analysis was used to group genotypes into distinct clusters based on ion selectivity and Na shoot content. These results provide the first example of the effectiveness of cluster analysis for evaluating physiological responses to salinity stress. More importantly, information concerning the differential genotypic response to salinity will provide the plant breeder with important tools for improving the salt tolerance in rice. Carbohydrate physiology in salinity tolerance mechanisms Identification of osmotically active metabolites produced by the plant in response to salinity stress is needed to provide plant breeders with physiological tools to develop salt tolerant plants. Two halophytic species of Limonium, L. perezii and L. sinuatum, were grown in greenhouse sand culture by ARS scientists at the George E. Brown, Jr. Salinity Laboratory in order to identify organic constituents in these species which may contribute to salt tolerance. Chiro-inositol, was isolated and identified from leaf tissues of both species. The enhanced accumulation of this unique sugar in response to salt stress contributes to cellular osmotic pressure and appears to be an important physiological process for the adaptation of Limonium to salinity stress. This work should provide new information for gene target search in transformation for enhanced crop salt tolerance. 5.Describe the major accomplishments over the life of the project, including their predicted or actual impact. Accomplishments are linked to NP201 Water Quality, and Managment; Components, Salinity, and Trace Element Management, Wastewater reuse. The presence of a Na+/H+ antiport mechanism in root membranes of tomato plants was reported by ARS Salinity Laboratory scientists. Impact: This finding was recently extended by molecular biologists working at the University of Toronto who reported the overexpression of a similar antiport mechanism in transgenic tomato which resulted in increased salt tolerance. Customers: Government, University, and private industry scientists, plant breeders. ARS scientists at the Salinity Laboratory identified physiological characters (leaf area index, Na-Ca selectivity, and K-Na selectivity) which contributed to salt tolerance in rice genotypes. Potential impact: Provides information for improving salt tolerance in rice. Customers: Government, University, and private industry scientists, plant breeders. A genetic population of rice from crosses between M202 and IR08 was developed by ARS scientists at the Salinity Laboratory. Leaf area index (LAI) was identified as a reliable physiological character which can be used to identify QTLs related to salt tolerance in rice. Potential impact: Provides plant breeders with physiological mechanism which can be exploited to improve salt tolerance in rice. Customers: Government, University, and private industry scientists, plant breeders. In a cooperative study, ARS scientists at the George E. Brown Jr. Salinity and at the Water Conservation Laboratory, Phoenix, AZ identified, selected, and registered a salt-tolerant germplasm of Lesquerella, WCL-SL1. Potential impact: A more salt-tolerant line of Lesquerella will result in increased production in salt-affected areas. Oil from this plant is used for industrial purposes. Customers: Seed companies, farmers, Government, University, and private industry scientists, plant breeders The effect of saline irrigation waters on biomass accumulation in “Haas” avocadogrown in greenhouse sand cultureswas studied by ARS scientists at the Salinity Laboratory. Chloride ion influx adversely influenced photosynthesis, thus limiting biomass accumulation in avocado. Provides plant breeders with physiological mechanism of salt tolerance. Customers: Government, University, and private industry scientists, plant breeders. 6.What science and/or technologies have been transferred and to whom? When is the science and/or technology likely to become available to the end-user (industry, farmer, other scientists)? What are the constraints, if known, to the adoption and durability of the technology products? None. Review Publications Liu, X., Wilson, C., Grieve, C.M. 2005. Effect of salinity on accumulation of chiro-inositol and other non-structural carbohydrates in limonium. In: Proceedings of the International Salinity Forum, Managing Saline Soils and Water: Science, Technology, and Soil Issues. April 25-27, 2005. Riverside, CA pp:93-96. Wilson, C., Liu, X., Zeng, L. 2005. Elevated CO2 influences salt tolerance of rice. In: Proceedings of the International Salinity Forum, Managing Saline Soils and Water: Science, Technology, and Soil Issues. April 25-27, 2005. Riverside, CA pp:481-484. Zeng, L. 2005. Exploration of relationship between physiological parameters and growth performance of rice (Oryza sativa L.) seedlings under salinity stress using multivariate analysis. Plant and Soil Journal. 268:51-59. Walia, H., Wilson, C., Close, T.J. 2005. Comparative transcriptional profiling of barley cultivar maythorpe and its derived mutant golden promise under salinity stress. Plant & Animal Genome XIII International Conference, San Diego, CA. Abstracts. Pg. 234. Zeng, L. 2004. Response and correlated response to salt tolerance selection in rice by yield parameters. Cereal Research Communications. 32(4):477-484. Zeng, L., Wilson, C., Grieve, C.M. 2004. Genetic improvement of salt tolerance in rice. ASA-CSSA-SSSA Annual Meeting Abstracts, CD-ROM, Seattle, WA.