PtWRKY2, a WRKY transcription factor from Pinellia ternata confers heat tolerance in Arabidopsis.

High temperatures are a major stress factor that limit the growth of Pinellia ternata. WRKY proteins widely distribute in plants with the important roles in plant growth and stress responses. However, WRKY genes have not been identified in P. ternata thus far. In this study, five PtWRKYs with four functional subgroups were identified in P. ternata. One group III WRKY transcription factor, PtWRKY2, was strongly induced by high temperatures, whereas the other four PtWRKYs were suppressed. Analysis of transcription factor characteristics revealed that PtWRKY2 localized to the nucleus and specifically bound to W-box elements without transcriptional activation activity. Overexpression of PtWRKY2 increased the heat tolerance of Arabidopsis, as shown by the higher percentage of seed germination and survival rate, and the longer root length of transgenic lines under high temperatures compared to the wild-type. Moreover, PtWRKY2 overexpression significantly decreased reactive oxygen species accumulation by increasing the catalase, superoxide dismutase, and peroxidase activities. Furthermore, the selected heat shock-associated genes, including five transcription factors (HSFA1A, HSFA7A, bZIP28, DREB2A, and DREB2B), two heat shock proteins (HSP70 and HSP17.4), and three antioxidant enzymes (POD34, CAT1, and SOD1), were all upregulated in transgenic Arabidopsis. The study identifies that PtWRKY2 functions as a key transcriptional regulator in the heat tolerance of P. ternata, which might provide new insights into the genetic improvement of P. ternata.

Transcriptome Analysis Reveals Long Non-Coding RNAs Involved in Shade-Induced Growth Promotion in Pinellia ternata.

BACKGROUND: High temperature and drought environments are important limiting factors for Pinellia ternata growth, whereas shading can promote growth by relieving these stresses. However, the mechanism of growth promotion by shading in P. ternata is unknown. Long non-coding RNAs (lncRNAs) play important roles in the plant's growth and environmental response, but few analyses of lncRNAs in P. ternata have been reported. METHODS: We performed lncRNAs analysis of P. ternata in response to shading using RNA-seq data from our previous studies. A total of 13,927 lncRNAs were identified, and 145 differentially expressed lncRNAs (DELs) were obtained from the comparisons of 5 days shade (D5S) vs. 5 days of natural light (D5CK), 20 days of shade (D20S) vs. 20 days of natural light (D20CK), D20S vs. D5S, and D20CK vs. D5CK. Of these, 119 DELs (82.07%) were generated from the D20S vs. D20CK comparison. RESULTS: Gene ontology (GO) analysis indicated that the reactive oxygen (ROS) metabolism and programmed cell death (PCD) processes might regulate shade-induced growth promotion. The "signal transduction" and "environmental adaptation" in the Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis were used for lncRNA-mRNA regulatory network construction and showed that the lncRNAs might mediate P. ternata growth by regulating ROS accumulation and light signals. CONCLUSIONS: This study explores lncRNAs' functions and regulatory mechanisms related to P. ternata growth and lays a foundation for further research on P. ternata.

Analysis of DNA methylation in potato tuber in response to light exposure during storage.

Exposure to light induces tuber greening and the accumulation of the toxic alkaloid Solanine in potato (Solanum tuberosum L) during storage greatly reduce tuber value. While the mechanism of this greening process remains unclear, it is well understood that DNA methylation plays an important role in regulating gene expression in response to environmental conditions. In this study, methylation-sensitive amplified polymorphism was used to assess the effect of light exposure on DNA methylation during storage of potato tubers. Light-induced genome-wide DNA demethylation and the rate of DNA methylation decreased with long storage times. Following, the sequencing of 14 differentially amplified fragments and analysis using the Basic Local Alignment Search Tool, eight genomic sequences and six annotated fragment sequences were identified. The latter included ADP glucose pyrophosphorylase 1/2, chlorophyllide a oxygenase 1 (CAO1), receptor-like protein kinase HAIKU2, and repressor of GA4, all of which are involved in starch biosynthesis, chlorophyll synthesis, endosperm development, and gibberellic acid signaling, respectively. Demethylation was observed in the CpG island (-273 to -166 bp) of the CAO1 promoter in response to light, which further confirmed that the variations in genome methylation are dependent upon the light exposure and suggests a direct role for DNA methylation. Our results provide an epigenetic perspective for further exploring the mechanism of light-induced tuber greening.