CRAG research team discovers a new strategy to achieve plants more tolerant to salinity

A CRAG research team achieves plants that are more tolerant to soil salinization by regulating the TEMPRANILLO genes, which opens up new possibilities to develop plant varieties better adapted to climate change

A recent article published in the scientific journal The Plant Journal sheds new light on the adaptive growth of plants and their ability to respond to adverse environmental conditions. The study, led by ICREA researcher at CRAG Soraya Pelaz, reveals the crucial role that TEMPRANILLO genes play in protecting plants from increased soil salinity, one of the major limiting factors for crop production. This discovery offers new strategies to develop plant varieties with greater climate resilience.

Together with the prolonged use of fertilizers in intensive agriculture, the increased evaporation of water from the soil caused by global warming is leading not only to less water availability, but also to increased concentrations of salts. Today, around 20% of cultivated lands are affected by salinization, but this percentage will increase due to the climate crisis caused by heat waves and drought.

“In our laboratory we investigate the TEMPRANILLO (TEM) genes, which regulate different stages of plant development, particularly flowering. In previous studies with the model plant Arabidopsis thaliana we found that plants with a reduced content of these factors flower earlier, hence the name of the genes [“temprano” meaning “early” in Spanish]. Surprisingly, after analysing plants with TEM excess, we saw that, in addition to changes in the flowering process, there were also alterations related to the response to salinity, so we decided to further investigate the role of TEM genes in adaptive growth” explains Pelaz.

Mutant plants with TEM excess and deficiency

To discover how TEM genes regulate plant growth under saline conditions, the team analysed mutant Arabidopsis plants with excess and deficiency of TEM grown in saline soils. In high concentrations of salt, normal plants flower later and produce almost no seeds, but the study found that mutant plants with TEM deficiency flower earlier, thus producing seeds, so their shorter life cycle allows them to escape the blockage of growth caused by salt.

“In addition, in the mutant plants with TEM deficiency we also observed that the aging of the leaves was delayed compared to that of normal plants, that is, the leaves took longer to turn yellow and dry out", points out Michela Osnato, first author of the article. “This is because these mutant plants produce less jasmonic acid, the aging hormone, and they also accumulate more vitamin E precursors that act as antioxidants during salt stress, leading to a slower degradation of photosynthetic pigments of the leaves, which turn from green to yellow”.

The work is based on a complex multilevel analysis that integrates molecular –gene expression–, metabolic –degradation of photosynthetic pigments and accumulation of antioxidants–, and physiological –changes in flowering and aging– data. Altogether, the multiple techniques used, carried out in collaboration with other CRAG research groups, reveal novel insights into the mechanisms that make TEM-deficient mutant plants more tolerant to salinity.

A sweet future

Salinity is known to pose a serious threat to agriculture because it blocks plant growth, and in high concentrations it can kill crops before they bear fruit and seeds. Therefore, the elucidation of the mechanisms involved in the response to saline stress is of great importance for the future of agriculture, since these findings can serve as a basis for developing crops with greater tolerance to climate change through biotechnological tools or by selecting varieties best adapted among the already existing ones.

“In the last decade, international groups have shown that many mechanisms discovered in the model plant Arabidopsis are conserved in plants of agronomic interest. Now, our team is investigating whether the TEM gene discovered in rice is also involved in the response to salinity”, adds Osnato. “The results we present in this study provide new strategies to regulate plant growth in saline soils: who knows if in the near future we will be able to use TEM genes in rice breeding programs to obtain varieties that better tolerate the growing salinity of the Ebro Delta, one of main rice production areas in Spain?”, concludes Pelaz.

Arabidopsis plants grown in saline soils for 3 weeks. On the left side, normal plants are depicted, which fail to flower. On the right side, mutant plants with TEM deficiency are able to produce flowers (indicated in blue circles)

Reference article

The Plant Journal. 27 October 2020 https://doi.org/10.1111/tpj.15048. The floral repressors TEMPRANILLO1 and 2 modulate salt tolerance by regulating hormonal components and photo‐protection in Arabidopsis. Michela Osnato, Unai Cereijo, Jan Sala, Luis Matías‐Hernández, Andrea E. Aguilar‐Jaramillo, María Rosa Rodríguez‐Goberna, José Luis Riechmann, Manuel Rodríguez‐Concepción, Soraya Pelaz.

About the funding of the study

This work was supported by MINECO‐MICIU/FEDER to Soraya Pelaz and José Luis Riechmann, and by the CERCA Programme/Generalitat de Catalunya and the ‘Severo Ochoa Programme for Centres of Excellence in R&D’/MICIU to CRAG. Andrea E. Aguilar‐Jaramillo and Unai Cereijo performed this work within the frame of a PhD Program of the Universitat Autònoma de Barcelona with an Investigator Training Program PhD fellowship from Generalitat de Catalunya and an FPI fellowship from the Spanish Ministry, respectively.