It is predicted that the world human population will reach about 11.2 billion by 2100 and with the climate change ahead water and food security have become one of the major challenges that humanity will have to face in the near future. On this context, agriculture as main source of human and animal food is of special importance. Improving and creating more resilient crops that would be able to grow on water limiting conditions is of special urgency. The study at genetic level of plants species that have naturally evolved and adapted to drought environments provides a source of knowledge to accomplish this necessity. In plants, the root system is responsible to uptake water and nutrients from the soil. When the environment conditions are adverse, such as drought conditions, the roots have to respond to these conditions. There are specific cell-types into the plant root, the endodermis and exodermis, that when differentiate forms barriers that can help to face these adverse conditions.
Nevertheless, to date, the molecular players which control exodermis differentiation remain unknown as well as whether the regulatory programs that determine endodermis and exodermis development are the same or distinct. The ROOT BARRIERS project has addressed these questions with the study of endodermis and exodermis differentiation in tomato, a plant species that develops both layers. We have studied the exodermis and endodermis differentiation using the domesticated Solanum lycopersicum ´M82´ and wild Solanum pennellii species as they have different root morphology and cellular development and have found they differs in their differentiation features. Moreover, our results suggest the endodermis and exodermis differentiation in tomato do not share same molecular regulators. Some studies have revealed that endodermis and exodermis differentiation occurs precociously in response to salt stress. The ROOT BARRIERS project has aimed to study how salt stress affects endodermis and exodermis differentiation in tomato roots also using S. lycopersicum ´M82´and S. pennellii. In addition, the role of these two cell types is of special interest as S.pennellii is salt tolerant specie and suggests that the environment is able to directly regulate the development of a specific cell type. We have generated stable transgenics plants to isolate the messenger RNA specifically from the endodermis and exodermis in control and salt stress conditions. This way we will be able to identify the regulators implicated in the differentiation of these two cell types and how salt stress is influencing the control of their differentiation at the molecular level.
