Informations et ressources scientifiques
sur le développement des zones arides et semi-arides

Titre : Identifying stress response genes and mechanisms in Anastatica hierochuntica, a relative of Arabidopsis from the Negev Desert that is tolerant to multiple abiotic stresses

Auteur : Eshel, Gil,

Etablissement de soutenance : Ben-Gurion University of the Negev

Grade : Doctor of Philosophy (PhD) 2016

Résumé partiel
Abiotic stresses such as high soil salinity, drought, and temperature extremes reduce average yields for most major crop plants by more than 50%. In addition, most new land with the potential for agriculture is situated in harsh environments. The requirement for food security for a rapidly increasing world population coupled with global climate change is driving the demand for improved tolerance of crops to abiotic stresses. Although promising abiotic stress tolerance genes have been identified, manipulation of these genes has often generated only a marginal effect on yield under field conditions. This is due to at least two reasons : (i) most abiotic stress research has focused on applying single stresses under controlled conditions. However, such experiments do not mimic a natural situation where plants are subjected to a combination of stresses ; (ii) plant stress studies have focused on the model plant Arabidopsis thaliana, which is stress-sensitive and is unlikely to possess many stress tolerance mechanisms found in naturally stress-tolerant plants - so-called extremophytes. Therefore, the main purpose of this study was to investigate the response of a naturally stress-tolerant desert extremophyte to both single and combined abiotic stresses.

We focused our research on species from the Brassicaceae plant family because this family includes the well-studied model plant A. thaliana and contains many economically important plants as well as various extremophytes that have been studied and which thrive in some of the most extreme environments. Furthermore, the genomes of many Brassicaceae have been sequenced thereby facilitating comparative analyses between related stress-sensitive and stress-tolerant species. In this study, we present Anastatica hierochuntica (Rose of Jericho), a Saharo-Arabian desert Brassicaceae species found in the Negev desert in Israel. We show that A. hierochuntica is tolerant to salt, heat, and low soil nitrogen stresses that are characteristic of its habitat. Taking salt tolerance as a case study, we demonstrate that A. hierochuntica exhibits several physiological features of salt tolerance that are similar to those observed in its Brassicaceae halophytic relative E. salsugineum, including tightly controlled Na+ accumulation and resilient photochemistry. Comparative metabolic profiling between Arabidopsis, E. salsugineum, and A. hierochuntica under control and salt stress conditions revealed both species-specific metabolic responses and common metabolic strategies between the two extremophytes including constitutive accumulation of the antioxidants, ascorbate and dehydroascorbate thereby supporting the notion that the extremophytes are primed for stress. Accordingly, A. hierochuntica displays remarkable tolerance to methyl viologen-induced oxidative stress suggesting that a highly active antioxidant system is essential to cope with the multiple abiotic stresses to which this plant is exposed.

Présentation et version intégrale (PRIMO)