Abstract

Flooding is an important environmental factor restricting plant growth and productivity throughout the world. Growth, organic solute accumulation and proteolytic activity of Medicago truncatula were determined in hydroponically grown plants exposed to hypoxia during 30, 45 and 60 days. Obtained results showed that hypoxia until 45 days have no significant impact on the dry matter production. However, after 60 days of treatment, a decrease in the shoot and root growth was observed. In addition, a development of adventitious roots is shown in the hypocotyle of treated plant. In fact, the water content varied in response to the hypoxia. The soluble carbohydrates content was still stable on the shoot of treated plant until 45 day. Whereas, it was registered that the content of non-reducing soluble sugar present almost all of total soluble sugars, and that the accumulation of this sugars fraction in more important in the roots of hypoxia plants in comparison to the aerial organs. The proline content measured in stressed plants was increased with time over control plants. Contrary, hypoxia decreased the total endopeptidase activity in M. truncatula roots. It could be concluded that M. truncatula can be support the prolonged hypoxic stress by developing adventitious roots and accumulating proline.

Key words: Medicago truncatula, hypoxia, adventitious roots, soluble sugars, proline, endopeptidase activity.