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Jorg Kudla



Dept. of Botany & Microbiology, College of Science, Building (5)

Office: AB 43

Telephone: 4675874

Project Title

Mechanisms of salt tolerance in Phoenix dactylifera and Atriplex halimus

Project Summary

Salinity causes enormous problems for agriculture especially in Saudi Arabia and other arid countries and increases the need for strategies that enable ecologically and economically worthwhile use of marginal and saline soils. The date palm (Phoenix dactylifera) is of large agronomic importance for Saudi Arabia and represents an extremophile plant with high tolerance against drought, salinity and heat. For P. dactylifera a complete genome sequence is available that aids the molecular investigation of its special physiological properties. Atriplex halimus is a monoecious C4 perennial shrub with extreme tolerance to drought and salinity. Moreover, A. halimus has promising potential for application in phytoremediation or usage as fodder plant that can be cultivated on marginal lands. Both species share a significant variation of stress tolerance between different populations.

This project aims to pursue a two-step strategy to use both species to advance our understanding on how halophytic plants establish their formidable salt tolerance. In a first step we will use the available molecular resources of P. dactylifera to identify and characterize components and mechanisms that bring about salt tolerance of this species. Building on this we will in a second step extend our approach to A. halimus. Here it is generally accepted that salt bladders are an important adaptation that is crucial for salt tolerance. However, salt bladders represent an end point of salt deposition and sodium ions need to be transported from the roots through the whole plant before it can be deposited in bladders. This requires that A. halimus in addition to salt bladders must have evolved mechanisms that allow efficient transport of sodium and avoidance of the accumulation of toxic cytoplasmic sodium concentrations during the transport through the root, shoot and leaves. These mechanisms – that likely involve - salt extrusion from roots, efficient transport and deposition in internal stores before salt reaches the bladders will be the focus of our investigations.

Specifically, this project aims to

1. Characterize and understand the natural variation that underlies salt tolerance in P. dactylifera and A. halimus.

2. Investigate the ion accumulation and distribution in tolerant and intolerant lines at highest possible resolution.

3. Analyze cytoplasmic Ca2+-dynamics in different tissues after extended salt stress and at different salt stress intensities.

4. Identify Ca2+-modulated regulatory networks in both species that bring about salt tolerance and characterize their specific configuration and adaptation for halophyte function.

5. Perform tissue specific transcriptomics analysis of salt stressed plants to identify novel components of salt tolerance.