Genes Expression of Key Enzymes in Phenylpropanes Metabolism Pathway in Cucumber with RT-PCR

Abstract

Phenylpropanoid metabolism is an important secondary metabolism pathway in plants. Lignin, as a secondary metabolite was produced by secondary metabolism pathway, plays important roles on disease resistance in plants. PAL, C4H, and CHS are key enzymes involved in the secondary metabolism pathway and critical on disease resistance. We hypothesize that the expression of key enzymes of secondary metabolism pathway will be affected by abnormal environmental conditions; therefore provide the resistance to severe environment for plant. In this study, we analysed the gene expressions of PAL, C4H, and CHS under higher temperature and infection of germ (Pseudoperonosporacubensis) in Cucumber JingChun No.4, which is highly resistant to downy mildew. The gene expressions were quantified by semi-quantitative RT-PCR. Our results showed that the expression of C4H was consistently higher and not affected by germ inoculation. However, the expressions of PAL and CHS were increased at 2 h and 25 h, respectively, after inoculating with germs. Interestingly, we found that the expressions of all these three genes were decreased with treatment of higher temperature. Our results demonstrated that PAL, C4H and CSH are important in secondary metabolism and affect the potential resistant ability of plant to various severe growing environments.

Ethylene Perception Is Associated with Methyl-Jasmonate-Mediated Immune Response against Botrytis cinerea in Tomato Fruit

“…The significant correlations between JA content and AOS activity indicated that AOS played an important role in endogenous JA production after MeJA treatment ( p < 0.01) . In addition, the close relationships among total phenolic content and PAL, C4H, 4CL, and POD activities could possibly be attributed to the fact that they are key enzymes and affect the generation of phenolic compounds in fruit, which contribute to improved disease resistance ( p < 0.05). ,, Furthermore, the significant correlations among ethylene, JA, and total phenolic content ( p < 0.05), indicated that there were significant positive relationships among ethylene, JA, and total phenolic contents. Besides, the ethylene content was positively correlated with 4CL activity ( p < 0.01), and the JA content were positively correlated with C4H, 4CL, and POD activities ( p < 0.01), which are involved in the phenolic metabolism.…”

“…Extensive studies demonstrated that MeJA-induced immune responses could be partially attributed to the activation of the phenylpropanoid pathway, because several phenylpropanoid metabolites are reported to have a direct effect on pathogens. ,, Phenolic compounds, which are critical secondary metabolites produced by the phenylpropanoid pathway, can be directly toxic to the pathogen or be deposited inside the cell walls, acting as a strong mechanical and biochemical barrier against pathogen invasion . PAL catalyzes the first step in the phenylpropanoid pathway to generate the phenolic compounds, which is also a widely used index to evaluate disease resistance . A previous study presented that overexpression of NtPAL remarkably enhanced disease resistance against Cercospora nicotianae, accompanied by higher levels of chlorogenic acid in tobacco plant .…”

“…47 PAL catalyzes the first step in the phenylpropanoid pathway to generate the phenolic compounds, which is also a widely used index to evaluate disease resistance. 36 A previous study presented that overexpression of NtPAL remarkably enhanced disease resistance against Cercospora nicotianae, accompanied by higher levels of chlorogenic acid in tobacco plant. 48 C4H and 4CL are also pivotal regulatory enzymes in the phenylpropane pathway, which are positively correlated with the disease resistance against gray mold.…”

“…48 C4H and 4CL are also pivotal regulatory enzymes in the phenylpropane pathway, which are positively correlated with the disease resistance against gray mold. 34,36 POD participates in the stiffening and strengthening of cell walls by inducing lignification, thereby inhibiting attempted fungal penetration. 49 In this study, MeJA treatment significantly enhanced the total phenolic content and elevated activities of PAL, C4H, 4CL, and POD (p < 0.05; Figure 4).…”

Integrating transcriptome and proteome analysis to determine the lignin synthesis pathway involved in Panax notoginseng in fungal stress

“…Phenylpropane metabolism is an important secondary metabolic pathway in plants. Lignin is a secondary metabolite produced by secondary metabolic pathways and plays an important role in plant disease resistance (Qiao et al 2013). In the process of plant growth and development, lignin synthesis and related metabolism play an important role.…”