Expression Of Trehalose Synthase Enes In Cassava And The Role In Drought Stress

Cassava (Manihot esculenta Crantz) belongs to the Euphorbiaceae. It mainly distributes in tropical and subtropical regions. It has many advantages, such as drought toleranc, infertile-resistant, easy cultivation and management, high yield and biomass, and so on. Cassava is a crop that contains relatively high amount of trehalose and is naturally resistant to water deficiency. Trehalose is a disaccharide that play an important role in drought resistance in plants. Trehalose-6-phosphate synthase (TPS) gene is the key gene in the trehalose synthesis pathway. Therefore, Our study on TPS gene has important theoretical and application value.Real-time quantitative PCR was used to study the relative expression and expression patterns of six drought stress-induced trehalose synthesis genes in cassava. Results indicated that six genes responsed to drought stress at different level and TPS1-3, TPS1-4, TPS6-4, TPS7-1, TPS9-2and TPS9-3may play vital roles in drougt tolerance.TPS1-3gene driven by CAMV35S promoter was transferred to the model plant Nicotiana benthamiana by Agrobacterium-mediate method, using leaf discs as explants. Through repeated screening, fouty-five resistant plantlets were obtained. PCR detection analysis showed that TPS1-3gene was integrated into ten of the plants. Real-time PCR showed that TPS1-3gene was transcribed in the four transgenic plant lines. HPLC/ELSD analysis revealed that transgenic lines accumulated0.1304-0.1785mg/g (FW) trehalose in the leaves. Osmotic stress experiments showed that detached leaves of transgenic plants had higher relative water content than that of non-transgenic plants. After rewatering, the transgenic plants recovered faster than the non-transgenic plants. Moreover, the electrolyte leakage rate of the leaves of transgenic plant lines was lower than those of non-transgenic plants. The germination rate of transgenic seeds was higher than those of non-transgenic plants on medium containing30%PEG6000. These results provide new evidence that tobacco plants transformed with the TPS1-3gene can accumulate high levels of trehalose, and have enhanced tolerance to drought.