Project description:Previous studies have shown that methane (CH4) has promoting roles in the adventitious root (AR) and lateral root formation in plants. However, whether CH4 could trigger the bulblet formation in scale cutting of Lilium davidii var. unicolor has not been elucidated. To gain insight into the effect of CH4 on the bulblet formation, different concentrations (1%, 10%,50% and 100%) of methane-rich water (MRW) and distilled water were applied to treat the scale cuttings of Lilium. We observed that treatment with 100% MRW obviously induced the bulblet formation in scale cuttings. To explore the mechanism of CH4-induced the bulblet formation, the transcriptome of scales was analyzed. A total of 2078 differentially expressed genes (DEGs) were identified. The DEGs were classified into different metabolism pathways, especially phenylpropanoid biosynthesis, starch and sucrose metabolism and plant signal transduction. Of these, approximately 38 candidate DEGs involved in the plant signal transduction were further studied. In addition, the expression of AP2-ERF/ERF, WRKY, GRAS, ARF and NAC transcription factors were changed by MRW treatment, suggesting their potential involvement in bulblet formation. As for hormones, exogenous IAA, GA and ABA could indue the bulblet formation. Additional experiments suggested that MRW could increase the endogenous IAA, GA, and JA levels, but decrease the levels of ABA during bulblet formation, which showed that higher IAA, GA, JA levels and lower ABA content might facilitate bulblet formation. In addition, the levels of endogenous hormone were consistent with the expression level of genes involved in phytohormone signal transduction. Overall, this study has revealed that CH4 might improve the bulblet formation of cutting scales in Lilium by regulating the expression of genes related to phytohormone signal transduction and transcription factors, as well as by changing the endogenous hormone levels.
Project description:Low temperature induces changes in plants at physiological and molecular levels, thus affecting growth and development. The Lanzhou lily (Lilium davidii, var. unicolor) is an important medicinal plant with high economic value. However, the molecular mechanisms underlying its photosynthetic and antioxidation responses to low temperature still remain poorly understood. This study subjected the Lanzhou lily to the two temperatures of 20°C (control) and 4°C (low temperature) for 24 h. Physiological parameters related to membrane integrity, photosynthesis, antioxidant system, and differentially expressed genes were investigated. Compared with control, low temperature increased the relative electrical conductivity by 43.2%, while it decreased net photosynthesis rate, ratio of variable to maximal fluorescence, and catalase activity by 47.3%, 10.1%, and 11.1%, respectively. In addition, low temperature significantly increased the content of soluble protein, soluble sugar, and proline, as well as the activity of superoxide dismutase and peroxidase. Comparative transcriptome profiling showed that a total of 238,109 differentially expressed genes were detected. Among these, 3,566 were significantly upregulated while 2,982 were significantly downregulated in response to low temperature. Gene Ontology enrichment analysis indicated that in response to low temperature, the mostly significantly enriched differentially expressed genes were mainly involved in phosphorylation, membrane and protein kinase activity, as well as photosynthesis, light harvesting, light reaction, and alpha,alpha-trehalose-phosphate synthase activity. Kyoto Encyclopedia of Genes and Genomes enrichment analysis also indicated that the most significantly enriched pathways involved ribosome biogenesis in eukaryotes, phenylalanine metabolism, circadian rhythm, porphyrin and chlorophyll metabolism, photosynthesis of antenna proteins, photosynthesis, and carbon fixation in photosynthetic organisms. Moreover, the expression patterns of 10 randomly selected differentially expressed genes confirmed the RNA-Seq results. These results expand the understanding of the physiological and molecular mechanisms underlying the response of the Lanzhou lily to low temperature stress.