Transcriptome Analysis Reveals the Molecular Mechanisms of BR Negative Regulatory Factor StBIN2 Maintaining Tuber Dormancy.

Potato is an important food crop. After harvest, these tubers will undergo a period of dormancy. Brassinosteroids (BRs) are a new class of plant hormones that regulate plant growth and seed germination. In this study, 500 nM of BR was able to break the dormancy of tubers. Additionally, exogenous BR also upregulated BR signal transduction genes, except for StBIN2. StBIN2 is a negative regulator of BR, but its specific role in tuber dormancy remains unclear. Transgenic methods were used to regulate the expression level of StBIN2 in tubers. It was demonstrated that the overexpression of StBIN2 significantly prolonged tuber dormancy while silencing StBIN2 led to premature sprouting. To further investigate the effect of StBIN2 on tuber dormancy, RNA-Seq was used to analyze the differentially expressed genes in OE-StBIN2, RNAi-StBIN2, and WT tubers. The results showed that StBIN2 upregulated the expression of ABA signal transduction genes but inhibited the expression of lignin synthesis key genes. Meanwhile, it was also found that StBIN2 physically interacted with StSnRK2.2 and StCCJ9. These results indicate that StBIN2 maintains tuber dormancy by mediating ABA signal transduction and lignin synthesis. The findings of this study will help us better understand the molecular mechanisms underlying potato tuber dormancy and provide theoretical support for the development of new varieties using related genes.

StBIN2 Positively Regulates Potato Formation through Hormone and Sugar Signaling.

Potato is an important food crop worldwide. Brassinosteroids (BRs) are widely involved in plant growth and development, and BIN2 (brassinosteroid insensitive 2) is the negative regulator of their signal transduction. However, the function of BIN2 in the formation of potato tubers remains unclear. In this study, transgenic methods were used to regulate the expression level of StBIN2 in plants, and tuber related phenotypes were analyzed. The overexpression of StBIN2 significantly increased the number of potatoes formed per plant and the weight of potatoes in transgenic plants. In order to further explore the effect of StBIN2 on the formation of potato tubers, this study analyzed BRs, ABA hormone signal transduction, sucrose starch synthase activity, the expression levels of related genes, and interacting proteins. The results show that the overexpression of StBIN2 enhanced the downstream transmission of ABA signals. At the same time, the enzyme activity of the sugar transporter and the expression of synthetic genes were increased in potato plants overexpressing StBIN2, which also demonstrated the upregulation of sucrose and the expression of the starch synthesis gene. Apparently, StBIN2 affected the conversion and utilization of key substances such as glucose, sucrose, and starch in the process of potato formation so as to provide a material basis and energy preparation for forming potatoes. In addition, StBIN2 also promoted the expression of the tuber formation factors StSP6A and StS6K. Altogether, this investigation enriches the study on the mechanism through which StBIN2 regulates potato tuber formation and provides a theoretical basis for achieving a high and stable yield of potato.

The Cysteine-Rich Peptide Snakin-2 Negatively Regulates Tubers Sprouting through Modulating Lignin Biosynthesis and H2O2 Accumulation in Potato.

Potato tuber dormancy is critical for the post-harvest quality. Snakin/Gibberellic Acid Stimulated in Arabidopsis (GASA) family genes are involved in the plants' defense against pathogens and in growth and development, but the effect of Snakin-2 (SN2) on tuber dormancy and sprouting is largely unknown. In this study, a transgenic approach was applied to manipulate the expression level of SN2 in tubers, and it demonstrated that StSN2 significantly controlled tuber sprouting, and silencing StSN2 resulted in a release of dormancy and overexpressing tubers showed a longer dormant period than that of the control. Further analyses revealed that the decrease expression level accelerated skin cracking and water loss. Metabolite analyses revealed that StSN2 significantly down-regulated the accumulation of lignin precursors in the periderm, and the change of lignin content was documented, a finding which was consistent with the precursors' level. Subsequently, proteomics found that cinnamyl alcohol dehydrogenase (CAD), caffeic acid O-methyltransferase (COMT) and peroxidase (Prx), the key proteins for lignin synthesis, were significantly up-regulated in silencing lines, and gene expression and enzyme activity analyses also supported this effect. Interestingly, we found that StSN2 physically interacts with three peroxidases catalyzing the oxidation and polymerization of lignin. In addition, SN2 altered the hydrogen peroxide (H2O2) content and the activities of superoxide dismutase (SOD) and catalase (CAT). These results suggest that StSN2 negatively regulates lignin biosynthesis and H2O2 accumulation, and ultimately inhibits the sprouting of potato tubers.

Simultaneous determination of ten active components in 12 Chinese Piper species by HPLC.

Piper is a genus that is recently valued for the treatment of central nervous system diseases. The major constituents, amides and lignans, are responsible for the antinociceptive and antidepressant activities. This study developed a RP-HPLC-UV method for the simultaneous determination of eight amides and two lignans in twelve different species of Piper. HPLC separation was accomplished on a C18 analytical column (5 µm, 250 mm × 4.6 mm, i.d.) with a gradient mobile phase consisting of acetonitrile and water at a flow rate of 1.0 ml/min. All the calibration curves showed good linear correlation coefficients (r > 0.9997) over the test ranges. The relative standard deviation of the current method was less than 2.90% for intra- and inter-day assays and the average recoveries were between 98.25% and 103.08%. The HPLC method established is appropriate for quality control purposes and allows for the differentiation of Piper species.

Studies on antidepressant and antinociceptive effects of ethyl acetate extract from Piper laetispicum and structure-activity relationship of its amide alkaloids.

Piper laetispicum C.DC. (Piperaceae), is an endemic climbing, glabrous plant distributed in the southern part of China. A novel alkaloid amide, Laetispicine, from it has been proven to possess antidepressant activity. In this present study, antidepressant and antinociceptive effects of the ethyl acetate extract (EAE) of P. laetispicum have been studied in forced swimming, open field, acetic acid writhing and formalin tests in KM mice. A significantly antidepressant-like effect was showing at doses of higher than 60 mg/kg, which was not due to an increase in locomotive activity. The EAE also presented an analgesic effect, in our studies. At lower doses (30 mg/kg) the antinociceptive effect was likely mediated via peripheral inflammation and changes in central processing, and at higher doses (120 mg/kg) that was due to both central and peripheral pathways. We also quantitatively analyzed the major components of EAE by HPLC and approached the structure-activity relationship between structure of amide alkaloids and its antidepressant activities. The antidepressant effective components of EAE might be Leatispiamide A and Laetispicine. In their molecular structures, the isolated double bond from benzene ring and conjugated double bond located at 2-3 and 4-5 were necessary for its antidepressant activity.

Antinociceptive and anti-inflammatory activities of ethyl acetate fraction from Zanthoxylum armatum in mice.

Zanthoxylum armatum DC. is a traditional Chinese medicine that is prescribed to alleviate pain and treat inflammatory disorders. This species is distributed mainly in the southeast and southwest regions of China. In the present study, we found that ethyl acetate fraction of ethanolic extract of Z. armatum could significantly decrease acetic acid-induced writhing numbers, and suppress formalin induced licking times in the first phase at the highest dose and in the second phase at all tested doses. This observation revealed that Z. armatum extract possessed powerful antinociceptive activity. The mechanisms of the antinociceptive effect might be mainly involved in the periphery inflammatory analgesic. In addition, the ethyl acetate fraction also inhibited xylene-induced ear swelling in a dose-dependent manner in mice. Eight lignans [eudesmin, horsfieldin, fargesin, kobusin, sesamin, asarinin, planispine A, and pinoresinol-di-3,3-dimethylallyl] were identified as major components of the ethyl acetate fraction. Considering related studies reporting the anti-inflammatory activity for the identified lignans, lignan might be responsible for its anti-inflammatory activity. Our results confirm that the traditional use of Z. armatum in the treatment of inflammation and pain is warranted.