Drought priming at seedling stage improves photosynthetic performance and yield of potato exposed to a short-term drought stress.

Potato (Solanum tuberosum L.) is an important food and vegetable crop worldwide. In recent years, the arid environment resulting from climate change has caused a sharp decline in potato yield. To clarify the effect of drought priming at the seedling stage on the tolerance of potato plants to drought stress during tuber expansion, we conducted a pot experiment to investigate the physiological response of the plants generated from seed potatoes of the variety 'Favorita' to varied water supply conditions: normal water supply at the seedling stage (control), normal water supply at the seedling stage and drought stress at the mid-tuber-expansion stage (non-primed), and drought priming at the seedling stage plus drought stress at the mid-tuber-expansion stage (primed). Drought priming resulted in an increase in the number of small vascular bundles in potato plants compared to non-primed plants. It also altered the shape and density of stomata, enhancing water use efficiency and reducing whole-plant transpiration. The primed plants maintained the basal stem cambium for a longer time under drought stress, which gained an extended differentiation ability to generate a greater number of small vascular bundles compared to non-primed plants. Drought priming increased the amount and rate of dry matter translocation, and so reduced the adverse effects on tubers of potato under drought stress. Therefore, drought priming at the seedling stage improved the photosynthetic performance and yield, and probably enhanced the drought tolerance of potato.

Systematic Analysis of Galactinol Synthase and Raffinose Synthase Gene Families in Potato and Their Expression Patterns in Development and Abiotic Stress Responses.

Raffinose family oligosaccharides (RFOs) are very important for plant growth, development, and abiotic stress tolerance. Galactinol synthase (GolS) and raffinose synthase (RFS) are critical enzymes involved in RFO biosynthesis. However, the whole-genome identification and stress responses of their coding genes in potato remain unexplored. In this study, four StGolS and nine StRFS genes were identified and classified into three and five subgroups, respectively. Remarkably, a total of two StGolS and four StRFS genes in potato were identified to form collinear pairs with those in both Arabidopsis and tomato, respectively. Subsequent analysis revealed that StGolS4 exhibited significantly high expression levels in transport-related tissues, PEG-6000, and ABA treatments, with remarkable upregulation under salt stress. Additionally, StRFS5 showed similar responses to StGolS4, but StRFS4 and StRFS8 gene expression increased significantly under salt treatment and decreased in PEG-6000 and ABA treatments. Overall, these results lay a foundation for further research on the functional characteristics and molecular mechanisms of these two gene families in response to ABA, salt, and drought stresses, and provide a theoretical foundation and new gene resources for the abiotic-stress-tolerant breeding of potato.

Transcriptome analysis reveals the proline metabolic pathway and its potential regulation TF-hub genes in salt-stressed potato.

Potato (Solanum tuberosum) is currently the third most important food crop in the world. However, the production of potato is seriously threatened by salt stress, which often occurs in the facility cultivation environment, and the mining of salt tolerance genes in potato remains to be further studied. In this study, test-tube plantlets of DM potato were treated with 200-mM NaCl to simulate salt stress, and 15 cDNA libraries were constructed for RNA-seq analysis. A total of 8383 DEGs were identified, of which 3961 DEGs were shared among all the salt treatments, and 264 (7.15%) TF-coding genes were identified from these shared DEGs. KEGG enrichment analysis showed that most DEGs identified from the "arginine and proline metabolism" (ko00330) were enriched in the proline metabolic pathway, and their functions almost covered the whole proline metabolic process. Further analysis showed that expression levels of all the 13 structural DEGs in the pathway were significantly up-regulated and proline accumulation was also significantly increased under salt stress, and 13 TF-hub genes were discovered by WGCNA in the lightcyan and tan modules which were highly positively correlated with the proline contents. Correlation analysis revealed that the four TF-hub genes of the lightcyan module and seven structural DEGs of the proline metabolic pathway might be the potential candidate genes, especially the potential and novel regulatory gene StGLK014720. Furthermore, the dual-luciferase reporter assay confirmed that the key protein StGLK014720 could activate the promoters of both structural genes StAST021010 and StAST017480. In conclusion, these results lay the foundation for further study on the salt tolerance mechanism of potato, and provide a theoretical basis and new genetic resources for salt tolerance breeding of potato.

[Effect of Electroacupuncture Stimulation at "Dazhui" (GV 14) and "Mingmen"(GV 4) on Cell Apoptosis of Spinal Cord and Expression of JNK Signaling Related Protein in Spinal Cord Injury Rats].

OBJECTIVE: To observe the effect of electroacupuncture (EA) stimulation at "Dazhui" (GV 14) and "Mingmen" (GV 4) of the Governor Vessel at different time-points on spinal cord neuronal apoptosis and the expression of c-Jun N-terminal kinases (JNK) protein in spinal cord injury (SCI) rats, so as to reveal its mechanism underlying improving SCI. METHODS: A total of 108 male SD rats were randomly divided into normal control, SCI model and EA groups which were further divided into 1, 3 and 7 d subgroups (12 rats/subgroup, 6 rats in each subgroup for TUNEL or Western blot, separately). SCI model was established by using the modified Allen's method. EA was applied to GV 14 and GV 4 for 20 min, once daily, for 1, 3 and 7 days, respectively. Basso-Beattie-Bresnahan (BBB) scale was adopted to assess the locomotor function of rats, the TUNEL method was used to examine neuronal apoptosis of injuried spinal cord, and the expression of phosphorylated (p)-c-Jun protein of T9-T11 spinal cord was detected by using Western blot. RESULTS: After modeling, the BBB scores of SCI rats on day 1, 3 and 7 were signi-ficantly decreased (P<0.01), while the numbers of apoptotic neuronal cells and the expression levels of p-c-Jun protein in the spinal cord were considerably increased at the 3 time-points in the model group (P<0.01, P<0.05). Following EA intervention, the decreased BBB scores on day 3 and 7, and the increased numbers of apoptotic neuronal cells on day 1, 3 and 7 and the up-regulated expression levels of p-c-Jun protein on day 3 and 7 were obviously suppressed (P<0.05, P<0.01). CONCLUSIONS: EA intervention can improve the locomotor function of SCI rats, which Feb be related to its effects in reducing neuronal apoptosis and down-regulating p-c-Jun protein in the injuried spinal cord.

Effects of Electroacupuncture at Governor Vessel Acupoints on Neurotrophin-3 in Rats with Experimental Spinal Cord Injury.

In an effort to explore new, noninvasive treatment options for spinal cord injuries (SCI), this study investigated the effects of electroacupuncture (EA) for SCI rat models. SCI was induced by a modified Allen's weight-drop method. We investigated the response of EA at Dazhui (GV 14) and Mingmen (GV 4) acupoints to understand the effects and mechanisms of EA in neuroprotection and neuronal function recovery after SCI. BBB testing was used to detect motor function of rats' hind limbs among groups, and EA was shown to promote the recovery of SCI rats' motor function. Nissl staining showed a restored neural morphology and an increase in the quantity of neurons after EA. Also, the antiapoptosis role was exposed by TUNEL staining. Western blotting analysis was used to determine the protein expression of neurotrophin-3 (NT-3) in spinal cord tissue. Compared to the sham group, the expression levels of NT-3 were significantly decreased and EA was shown to upregulate the expression of NT-3. The present study suggests that the role of EA in neuroprotection and dorsal neuronal function recovery after SCI in rats, especially EA stimulation at GV 14 and GV 4, can greatly promote neuronal function recovery, which may result from upregulating the expression of NT-3.

Electroacupuncture at Dazhui (GV14) and Mingmen (GV4) protects against spinal cord injury: the role of the Wnt/ß-catenin signaling pathway.

Electroacupuncture at Dazhui (GV14) and Mingmen (GV4) on the Governor Vessel has been shown to exhibit curative effects on spinal cord injury; however, the underlying mechanism remains poorly understood. In this study, we established rat models of spinal cord injury using a modified Allen's weight-drop method. Ninety-nine male Sprague-Dawley rats were randomly divided into three equal groups: sham (only laminectomy), SCI (induction of spinal cord injury at T10), and EA (induction of spinal cord injury at T10 and electroacupuncture intervention at GV14 and GV4 for 20 minutes once a day). Rats in the SCI and EA groups were further randomly divided into the following subgroups: 1-day (n = 11), 7-day (n = 11), and 14-day (n = 11). At 1, 7, and 14 days after electroacupuncture treatment, the Basso, Beattie and Bresnahan locomotor rating scale showed obvious improvement in rat hind limb locomotor function, hematoxylin-eosin staining showed that the histological change of injured spinal cord tissue was obviously alleviated, and immunohistochemistry and western blot analysis showed that Wnt1, Wnt3a, ß-catenin immunoreactivity and protein expression in the injured spinal cord tissue were greatly increased compared with the sham and SCI groups. These findings suggest that electroacupuncture at GV14 and GV4 upregulates Wnt1, Wnt3a, and ß-catenin expression in the Wnt/ß-catenin signaling pathway, exhibiting neuroprotective effects against spinal cord injury.