Endogenous salicylic acid shows different correlation with baicalin and baicalein in the medicinal plant Scutellaria baicalensis Georgi subjected to stress and exogenous salicylic acid

Abstract

Salicylic acid (SA) is synthesized via the phenylalanine lyase (PAL) and isochorismate synthase (ICS) pathways and can influence the stress response in plants by regulating certain secondary metabolites. However, the association between SA and particular secondary metabolites in the Chinese medicinal plant Scutellaria baicalensis Georgi is unclear. To elucidate the association between SA and the secondary metabolites baicalin and baicalein, which constitute the primary effective components of S. baicalensis, we subjected seedlings to drought and salt stress and exogenous SA treatment in a laboratory setting and tested the expression of PAL and ICS, as well as the content of free SA (FSA), total SA (TSA), baicalin, and baicalein. We also assessed the correlation of FSA and TSA with PAL and ICS, and with baicalin and baicalein accumulation, respectively. The results indicated that both FSA and TSA were positively correlated with PAL, ICS, and baicalin, but negatively correlated with baicalein. The findings of this study improve our understanding of the manner in which SA regulates secondary metabolites in S. baicalensis.

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“…At 21 dpi of all treatments, the transcription levels of four tomato-innate defense genes (PAL, PR-1, CHS, and POD) were investigated. Beside it is the first enzyme in the phenylpropanoid pathway linking the primary and secondary metabolism [61], PAL is involved in salicylic acid (SA) biosynthesis [62]. SA is an important signal that regulates systemic acquired resistance (SAR) in plants [42,63] and its role in plant immunity has been investigated for decades.…”

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“…For example, in Arabidopsis and tobacco ( Nicotiana tabacum ), SA is synthesized by the PAL pathway. In soybean ( Glycine max ), both pathways contribute to SA biosynthesis 34 . The ICS pathway is generally considered to be the main source of continuous SA biosynthesis, while the PAL pathway synthesizes SA rapidly only in locally necrotic cells 35 .…”

Applications, phytochemistry, pharmacological effects, pharmacokinetics, toxicity of Scutellaria baicalensis Georgi. and its probably potential therapeutic effects on COVID-19: a review

“…Therefore, it is suggested that the above-mentioned step should be cancelled in the modern processing of SB, so as to ensure the quality of SB [ 28 , 29 ]. The total amount of baicalin and flavonoids in the process of drying shows a change trend of inverted “V”, which may be related to the physiological mechanism of anti-drought stress of SB root itself [ 26 , 30 ]. This showed that the drying time should not be too long, otherwise the content of active ingredients will be reduced.…”