Genome-Wide Identification and Characterization of the Trehalose-6-phosphate Synthetase (TPS) Gene Family in Watermelon (Citrullus lanatus) and Their Transcriptional Responses to Salt Stress

Abstract

With the increase in watermelon cultivation area, there is an urgent need to explore enzymatic and genetic resources for the sustainable development of watermelon, especially under salt stress. Among the various compounds known, trehalose plays an important role in regulating abiotic stress tolerances in diverse organisms, including plants. Therefore, the present study comprehensively analyzed the trehalose-6-phosphate synthase (TPS) gene family in watermelon. The study analyzed the functional classification, evolutionary characteristics, and expression patterns of the watermelon TPS genes family. Seven ClTPSs were identified and classified into two distinct classes according to gene structure and phylogeny. Evolutionary analysis suggested the role of purifying selection in the evolution of the TPS family members. Further, cis-acting elements related to plant hormones and abiotic stress were identified in the promoter region of the TPS genes. The tissue-specific expression analysis showed that ClTPS genes were widely expressed in roots, stems, leaves, flowers, and fruits, while ClTPS3 was significantly induced under salt stress. The overexpression of ClTPS3 in Arabidopsis thaliana significantly improved salt tolerance. Finally, the STRING functional protein association networks suggested that the transcription factor ClMYB and ClbHLH regulate ClTPS3. Thus, the study indicates the critical role of ClTPS3 in watermelon response to salt stress.

Comparative Transcriptome Analysis Reveals Differential Gene Expression in Resistant and Susceptible Watermelon Varieties in Response to Meloidogyne incognita

“…All primers were synthesized by SunYa (Zhengzhou, China). qRT-PCR was performed on the Light Cycler480 Real-Time System (Bio-Rad Laboratories, Hercules, CA, USA) with the following steps [ 28 ]: 45 cycles of 95 °C for 5 min, 95 °C for 10 s, 58 °C for 10 s and 72 °C for 10 s, followed by a melting curve analysis. Each reaction mix contained 1.0 μL previously diluted cDNA (1:5), 10.0 μL TB Green Premix Ex TaqTM II (Tli RNaseH Plus) (TaKaRa) and 10.0 mM of each primer, for filling a final volume of 20 μL using 7 μL RNase-free water.…”

Transcriptomic and Metabolomic Analysis of the Effects of Exogenous Trehalose on Salt Tolerance in Watermelon (Citrullus lanatus)

“…The MDA, POD, SOD, and CAT content were determined according to Yuan et al [ 26 ] using KTB1050, KTB1150, KTB1030, and KTB1040 (Abbkine, Beijing, China) kits, respectively. The Na + and K + content were determined using sodium assay kit (C002-1-1) and potassium assay kit (C001-2-1) (Nanjing Jiancheng Bioengineering Institute, Nanjing, China), respectively.…”

“…Online software ( , accessed on 10 April 2022) was used to design specific primers, which were shown in Table S1 . qPCR was performed on the Light Cycler480 Real-Time System (Bio-Rad Laboratories, Hercules, CA, USA) with the method described previously [ 26 ]: 95 °C for 5 min, 40 cycles of 95 °C for 10 s, 58 °C for 10 s, and 72 °C for 10 s. Each reaction mixture (final volume was 20 μL) contained 1.0 μL cDNA, 10.0 μL AMP SYBR Green (Low ROX) (Bioman, Chian), 1.0 μL primer (10 mM working solution) and 7.0 μL sterile water. The 2 −ΔΔCt method was used to calculate the expression of DEGs [ 38 ].…”

“…In higher plants, TPS and TPP are generally widespread in the form of large gene families [ 19 ]. The overexpression of TPS or TPP gene can significantly increase trehalose content in transgenic plants and improve stress tolerance [ 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 ].…”

Comparative Transcriptome Profiling Provides Insights into Plant Salt Tolerance in Watermelon (Citrullus lanatus)

“…The MDA content was determined according to Yuan et al [ 14 ] using a KTB1050, (Abbkine, Beijing, China) kit, and then the absorbance values at 532 nm and 660 nm were determined, respectively. The Na + , Cl − , and K + content was determined using a sodium assay kit (C002-1-1), chlorine assay kit (C003-2-1), and potassium assay kit (C001-2-1) (Nanjing Jiancheng Bioengineering Institute, China), and the wavelength of Na + , Cl − , and K + was 620 nm, 480 nm, and 450 nm, respectively.…”