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

Accueil du site → Doctorat → Espagne → 2018 → Comparative analyses of plant responses to drought and salt stress in related taxa : A useful approach to study stress tolerance mechanisms

Universitat Politècnica de València (2018)

Comparative analyses of plant responses to drought and salt stress in related taxa : A useful approach to study stress tolerance mechanisms

AL HASSAN, MOHAMAD

Titre : Comparative analyses of plant responses to drought and salt stress in related taxa : A useful approach to study stress tolerance mechanisms

Auteur : AL HASSAN, MOHAMAD

Université de soutenance : Universitat Politècnica de València

Grade : Doctoral Tesis 2018

Résumé
Salinity and drought are the most important environmental stress conditions reducing crop yields worldwide and limiting the distribution of wild plants in nature. Soil salinity, especially secondary salinity caused by anthropogenic practices, such as prolonged irrigation, lead to substantial agricultural yield losses, especially in arid and semiarid regions. Drought, caused by reduced water content in the soil, occurs due to disorders in nature’s water cycle, chiefly when evapotranspiration exceeds precipitation in a certain area, to the point where soil water reserves can no longer support plant growth. Drought and salt stress trigger the activation of a series of basic stress mechanisms that includes among others, the control of ion transport, exclusion and compartmentalization, as well as the accumulation of compatible solutes (’osmolytes’), and the activation of antioxidant systems. These mechanisms are conserved in all plants, stress tolerant and sensitive alike, and don’t necessarily confer tolerance. To decipher those mechanisms and have a better understanding on the contribution of different stress responses to the stress tolerance of a given species, we have carried out comparative studies on the responses to drought and salinity in a number of genetically related taxa with different tolerance potentials. Methodology The experimental approach was mostly based on i) establishing the relative tolerance to water and salt stress in the studied species from their distribution in nature (in the case of wild species) and through the relative inhibition of growth in the presence of stress, and ii) correlating changes in the levels of biochemical ’stress markers’ associated to specific response pathways (ion transport, osmolyte accumulation¿) upon stress treatments, with the already established relative tolerance to stress. This strategy proved to be appropriate to distinguish mere general responses to stress from those mechanisms relevant for stress tolerance of the investigated species and cultivars. The work also sheds light on other aspects affected by salt stress, specifically regarding germination and reproductive success or anatomical changes in salt-stressed plants. The expression patterns of the gene NHX1, encoding a vacuolar Na+/H+ antiporter were also studied in the Plantago taxa, as a first step in the full characterisation of this ion transporter, that appears to play an important role in the mechanisms of salt tolerance in this genus. Conclusion The results obtained in this work contribute to a better understanding of general stress tolerance mechanisms in plants, and provides clear insights into the mechanisms conferring tolerance, specifically, to drought and salt stress in some wild species and crops. This work also shed more light on the highly efficient responses to stress in halophytes, plants that could be viewed as nature’s answer to the aforementioned adverse environmental conditions via evolution and adaptation. Halophytes can therefore be considered as a suitable source - underutilized at present, in our opinion - of knowledge, genetic resources and biotechnological tools for the needed improvement of stress tolerance in crops

Mots Clés  : Salt stress , Drought , Halophytes , Glycophyte , Osmolyte , Antioxidant , Ion transport , Juncus , Phaseolus , Plantago , Tolerance , Response

Présentation

Version intégrale (6,8 Mb)

Page publiée le 19 décembre 2021