The Synthesis of Ascorbic Acid in Rice Roots Plays an Important Role in the Salt Tolerance of Rice by Scavenging ROS.

The root plays an important role in the responses of plants to stresses, but the detailed mechanisms of roots in stress responses are still obscure. The GDP-mannose pyrophosphate synthetase (GMPase) is a key factor of ascorbic acid (AsA) synthesis in rice roots. The present study showed that the transcript of was induced by salt stress in roots, but not in leaves. Inhibiting the expression of by RNA interfering (RI) technology significantly impaired the tolerance of rice to salt stress. The roots of RI plants rapidly produced more O₂, and later accumulated amounts of H₂O₂ under salt stress, indicating the impaired tolerance of RI plants to salt stress due to the decreasing ability of scavenging reactive oxygen species (ROS). Moreover, exogenous AsA restored the salt tolerance of RI plants, indicating that the AsA synthesis in rice roots is an important factor for the response of rice to salt stress. Further studies showed that the salt-induced AsA synthesis was limited in the roots of RI plants. The above results showed that specifically regulating AsA synthesis to scavenge ROS in rice roots was one of important factors in enhancing the tolerance of rice to salt stress.