A legume's response to lack of water

Oeiras, 27.05.11

For some time, researchers stuck to the formula “DNA makes RNA makes protein makes life” and studied life processes accordingly. This has been complicated by the discovery that small RNA molecules, which do not code for proteins, affect protein coding RNAs, thus regulating many physiological and developmental processes in living organisms. ITQB researchers from the Plant Cell Biotechnology Lab now show how small RNA regulatory pathways are involved in water deficit response in plants. This indication comes from studies in the model legume, Medicago truncatula, now published in BMC Plant Biology.

In their work, researchers started by identifying in the Medicago genome, those genes know to play a role in RNA processing in other organisms. Sequence comparison placed each of the 15 genes in its corresponding gene family. Gene expression was then assessed in adult Medicago plants subjected to mild and severe water deficit, revealing changes that were reversed by re-watering the plants.

The results were more evident in roots and for two enzymes involved in the processing and activation of microRNAs (Dicer like 1 and Argonaut 1), whose gene expression increases under water stress. Accordingly, the level of micro RNAs affecting the expression of these genes decreased under the same conditions. Moreover, the expression of genes involved in DNA methylation, a process known to alter gene expression patterns, was also found to increase.

This study supports the idea that legume plants react to water shortage through the small RNA regulatory pathway, which in turn, modulates gene expression and thus the plant physiological response.

Original Article

BMC Plant Biol. 2011 May 10;11:79.

In Medicago truncatula, water deficit modulates the transcript accumulation of components of small RNA pathways

Cláudio Capitão , Jorge AP Paiva , Dulce M Santos and Pedro Fevereiro