Low Temperature Induces the Accumulation of Phenylalanine Ammonia-Lyase and Chalcone Synthase mRNAs of Arabidopsis thaliana in a Light-Dependent Manner

Abstract

Anthocyanins, which accumulate in leaves and stems in response to low temperature and changes in light intensity, are synthesized through the phenylpropanoid pathway that is controlled by key enzymes that include phenylalanine ammonia-lyase (PAL) and chalcone synthase (CHS). In this work we demonstrate that PAL and CHS mRNAs accumulate in leaves of Arabidopsis thaliana (1.) Heynh. upon exposure to low temperature in a light-dependent manner. The regulation of the PALl gene expression by low temperature and light was examined by analyzing the expression of the P-glucuronidase (uidA) reporter gene in transgenic Arabidopsis plants containing the uidA gene of Escherichia coli under the control of the PALl promoter. The results indicate that the accumulation of PAL 7 mRNA is transcriptionally regulated. Histochemical staining for P-glucuronidase activity showed that the PAL7 promoter i s preferentially activated in photosynthetically active cells, paralleling anthocyanin accumulation. Moreover, we show that light may also be implicated in the regulation of the CHS gene in response to bacterial infiltration. Finally, using two fransparent testa Arabidopsis mutants that are unable to accumulate anthocyanins, we demonstrate that these pigments are not required for successful development of freezing tolerance in this species.

Role of Temperature and Soil Moisture Conditions on Flavonoid Production and Biosynthesis-Related Genes in Ginkgo (Ginkgo biloba L.) Leaves

“…These results imply that lower temperature improves the expression of PAL gene, while soil moisture content has a negligible effect on its expression, as evident by the clear relation between PAL expression and the biosynthesis of flavonoid. Similar observations of PAL increased expression were reported after exposure to low temperature in Arabidopsis thaliana leaves [30] and tomato (Solanum lycopersicum) plants [31]. Additionally, the unclear role of moisture effect on PAL gene expression was also supported by the conflicting observations in Camellia sinensis [32] and Scutellaria baicalensis [33] which showed decreased and increased PAL expression under water deficit conditions, respectively.…”

Tocopherols Play a Crucial Role in Low-Temperature Adaptation and Phloem Loading in Arabidopsis

“…Consistent with the purple color of mature leaves of 7.58C-treated vte2 mutants ( Figure 3B), vte2-1 accumulated significantly higher levels of anthocyanins than Col after 14 d of 7.58C ( Figure 4D). In Col, anthocyanins were detected only at 7 d. Because anthocyanin accumulation is often associated with plant responses to stress (Leyva et al, 1995;Chalker-Scott, 1999) and tocopherols are well-characterized lipid-soluble antioxidants in animals Liebler, 1995, 1997), it seemed plausible that increased lipid peroxidation might be occurring in vte2-1 during low-temperature treatment. However, the lipid peroxide levels of vte2-1 and Col analyzed by the ferrous oxidation xylenol orange assay were found to be similar and near background levels at all time points ( Figure 4B), indicating that the observed phenotypic differences between 7.58C-treated vte2-1 and Col are not associated with a detectable increase in lipid peroxidation.…”

Cloning and characterization of a cold inducible Pal promoter from Fagopyrum tataricum

“…These results show that PFtPal has an important role in regulation of transcription and to environment stimulon. PAL is an important enzyme in phenylpropanoid metabolic pathway [28], and the expression level of PAL is highly related to the synthesis of flavonoids [3,29]. The role in spatio-temporal expression of Pal promoters have previously been reported [8,11,30].…”

“…Expression of PAL could be induced by various stress-related stimuli including low temperature, bending stress, and light in many plant species. The expression level of PAL effectively influences the biosynthesis of flavonoids [2,3]. As an important component of eukaryote gene expression regulation, the promoter plays an important role in spatial and temporal regulation of gene expression via controlling the efficiency of start and start frequency.…”