Rhizosheath Holds the Key to Desert Plant’s Heat Tolerance: Study

Desert may be hell to many, desolate and uninhabited, with fatal heat and aridness; but not to all. Some plants can survive the extremely unsuitable environment in the wilderness, fighting with high temperature and lack of water, as well as the strong wind. 

Stipagrostispennata (Trin.)de Winter, or Stipagrostispennata, is such a hero of desert survival. The plant mostly is found in China’s Xinjiang region, central Asia, and Europe. It lives on the top of drifting sand dunes, and can stand the harsh test of desert environment. That makes it a better choice for drift dune restoration. 

But what aretheir secrets of doing so? 

Scientists with the Xinjiang Institute of Ecology and Geography may have found its powerful weapon for heat tolerance and drought resistance. Secret lies in its rhizosheath, a boot-like structure composed of sand particles, root surface exudates and microorganism exudates, root hairs, and mycelium. 

Thick root hairs and mycelium together bind the sand particles tightly to the roots, with the help of the glue-like substances such as the exudates secreted by microorganism on the root surface. The binding structure forms a tube, which expand the contact area of roots and soil. This enables the plant more nutrients and water from the sand bed layer. 

The cavity formed between the sheath and the root provides the plant more protection from heat and severe cold. When it rains in the desert, the water can be stored in the cavity, reserved to resist timeless drought. 

Also, the sheath will play the role of a shell, to keep away the mechanical rub of sand particles, and reduce water desorption.  

Further study also unravels the key characters in helping the sheath to give its ecological functions a full play. A special microbial community in the sheath enjoys higher utilization of carbon sources. And among them, abundant Rhizobialesazotobacterin the sheath helps the plant to absorb Nitrogen more effectively. 

Microorganisms in the rhizosheath of the Stipagrostispennata affect not only its adhesive ability, but also the formation of the sheath, and even its seed germination and the seedling survival rate.