Knocking Down the Expression of GMPase Gene OsVTC1-1 Decreases Salt Tolerance of Rice at Seedling and Reproductive Stages

Abstract

Salinity is a severe environmental stress that greatly impairs production of crops worldwide. Previous studies have shown that GMPase plays an important role in tolerance of plants to salt stress at vegetative stage. However, the function of GMPase in plant responses to salt stress at reproductive stage remains unclear. Studies have shown that heterologous expression of rice GMPase OsVTC1-1 enhanced salt tolerance of tobacco seedlings, but the native role of OsVTC1-1 in salt stress tolerance of rice is unknown. To illustrate the native function of GMPase in response of rice to salt stress, OsVTC1-1 expression was suppressed using RNAi-mediated gene silencing. Suppressing OsVTC1-1 expression obviously decreased salt tolerance of rice varieties at vegetative stage. Intriguingly, grain yield of OsVTC1-1 RNAi rice was also significantly reduced under salt stress, indicating that OsVTC1-1 plays an important role in salt tolerance of rice at both seedling and reproductive stages. OsVTC1-1 RNAi rice accumulated more ROS under salt stress, and supplying exogenous ascorbic acid restored salt tolerance of OsVTC1-1 RNAi lines, suggesting that OsVTC1-1 is involved in salt tolerance of rice through the biosynthesis regulation of ascorbic acid. Altogether, results of present study showed that rice GMPase gene OsVTC1-1 plays a critical role in salt tolerance of rice at both vegetative and reproductive stages through AsA scavenging of excess ROS.

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

“…Inhibiting the expression of OsVTC1-3 resulted in the rapid accumulation of H 2 O 2 in rice roots under salt stress; in contrast, there was no obvious H 2 O 2 accumulation in rice leaves ( Figure 3 ). Different from OsVTC1-3 , the previous study showed that rice GMPase gene OsVTC1-1 played an important role in scavenging ROS in rice leaves [ 28 ], indicating that rice GMPase homologous genes OsVTC1-1 and OsVTC1-3 may be involved in the salt response in rice different organs, OsVTC1-1 in leaves and OsVTC1-3 in roots by regulating ROS dynamics.…”

“…The exogenous AsA rescued most tolerance of OsVTC1-3 RI plants to salt stress, showing that the role of OsVTC1-3 in regulating AsA synthesis was important for rice roots to scavenge ROS and enhance the tolerance of rice to salt stress ( Figure 4 ) Salt stress rapidly induced OsVTC1-3 expression and increased AsA biosynthesis in rice roots ( Figure 1 ), and decreasing the expression of OsVTC1-3 significantly impaired the salt-induced AsA synthesis in rice roots ( Figure 5 ), indicating that OsVTC1-3 is involved in rice salt response by regulating AsA synthesis in rice roots under salt stress. In contrast, the homologous OsVTC1-1 played an important role in salt response in rice leaves due to regulating AsA biosynthesis in rice leaves [ 17 , 28 ]. In all, the results from the present work suggested that, different from homologous OsVTC1-1 , which regulates AsA biosynthesis and the salt response of rice leaves, rice can specifically activate the transcript of OsVTC1-3 in rice roots to promote AsA synthesis to scavenge ROS in rice roots to improve the salt tolerance of rice under salt stress.…”

“…A previous study showed that OsVTC1-1 and OsVTC1-3 were responsible for AsA synthesis in leaf and root, respectively. In contrast, OsVTC1-8 may not be involved in AsA synthesis [ 17 ], and OsVTC1-1 plays an important role in the response of rice to salt stress by regulating the redox homeostasis in the rice foliar organ [ 28 ]. The results from this study showed that rice GMPase gene OsVTC1-3 plays a major role in scavenging the rapidly accumulated ROS in rice root and enhances the tolerance of rice to salt stress by regulating AsA synthesis in rice root.…”

Transcriptome analysis of strawberry (Fragaria × ananassa) fruits under osmotic stresses and identification of genes related to ascorbic acid pathway

“…In Arabidopsis, Atvtc1-1 (GMP) mutant shows impaired production of AsA (Conklin et al ), and an enhancement of salt tolerance was associated to the binding of AtERF98 to the AtVTC1–1 promoter. Moreover, knocking down the expression of rice GMP gene decreases its salt tolerance (Qin et al ). The next step in this pathway, the conversion of GDP‐ d ‐mannose to GDP‐ l ‐Galactose (GDP‐ l ‐Gal), is catalyzed by GDP‐ d ‐mannose–30, 50‐epimerase (GME).…”

Advances and Challenges in the Breeding of Salt-Tolerant Rice

“…The overexpression of APX genes in rice reduces ROS levels and enhances salt tolerance [73][74][75]. The knockdown of OsVTC1-1 and OsVTC1-3, which are involved in ascorbate synthesis, increases the accumulation of ROS and decreases the salt resistance of rice [76][77][78].…”