Skip to main content

Yeast as a tool to determine proteins important for drougth tolerance of Selaginella lepidophylla

Final Activity Report Summary - DROUGHTSTRESS (Yeast as a tool to determine proteins important for drougth tolerance of Selaginella lepidophylla)

The improvement of the tolerance to abiotic stress in crop plants is a very important research area in the world. A common research strategy to identify genes capable to confer new traits to crops is the study of naturally occurring plants containing the desired trait. In this regard, we have studied the very interesting plant Selaginella lepidophylla for its exceptional drought tolerance. This plant is able to survive in a complete dry form for many years. One of the reasons for its high stress tolerance is the very high trehalose level found in this plant. Trehalose is well-known molecule for its stress protection characteristics. It is synthesized in two steps where the TPS enzyme catalyses the formation of trehalose-6-phosphate that is then converted to trehalose by the activity of the TPP enzyme. Although most higher plants do not accumulate high concentrations of trehalose it is generally assumed that all the plants contain trehalose biosynthesis genes.

The role of the metabolism of trehalose in non-stress resistance plants (as the most of crops) is not completely known but there is a well-established link with development, photosynthesis, starch synthesis and stress responses. The artificial modification of the metabolism of trehalose by introducing trehalose biosynthesis genes resulted in improved stress tolerance but there were also some non-desired traits. This requires the identification of new genes capable to reduce the undesired effects and a better understanding of the effects upon manipulation of the metabolism of trehalose.

During this fellowship we focused the work on two general aims: on one hand the search of new genes capable to improve the drought tolerance in plants and on the other hand we introduced a new plant model to try to understand the mechanism how the metabolism of trehalose works in plants. An important result of our work is the cloning and functional characterization of the first naturally-occurring bi-functional TPS-TPP protein, a finding that opens new biotechnological alternatives to the synthesis and accumulation of trehalose in genetically modified organisms (GMO). For that reason the VIB patented the gene.

In addition, the discovery of this type of gene was a central key in the comprehension of the origin and the evolutionary history reconstruction of the TPS genes in plants that we were able to unravel. This work is finished and under publication process. On the other hand we have cloned several stress-related genes and two Class III TPP genes from S. lepidophylla. We are still in the process of the selection of transgenic plants overexpressing those genes but we expect an improvement of the drought tolerance.

Finally, we have started the study of the metabolism of trehalose in the moss Physcomitrella patens. We found that this unique plant model is a suitable model system to study the roles of single TPS and/or TPP genes in plants. Our data shows that the expression of TPS, TPP and trehalase genes as well as the trehalose content are modified by stress and ABA (Abscisic Acid) suggesting that the mechanisms by which the metabolism of trehalose is involved in the response to abiotic stress was determined early in evolution of plants and that it is possible to make comparative analysis between mosses and flowering plants.