Molecular cloning, characterization, and promoter analysis of the isochorismate synthase (AaICS1) gene from Artemisia annua

Abstract

Abstract:Isochorismate synthase (ICS) is a crucial enzyme in the salicylic acid (SA) synthesis pathway. The full-length complementary DNA (cDNA) sequence of the ICS gene was isolated from Artemisia annua L. The gene, named AaICS1, contained a 1710-bp open reading frame, which encoded a protein with 570 amino acids. Bioinformatics and comparative study revealed that the polypeptide protein of AaICS1 had high homology with ICSs from other plant species. Southern blot analysis suggested that AaICS1 might be a single-copy gene. Analysis of the 1470-bp promoter of AaICS1 identified distinct cis-acting regulatory elements, including TC-rich repeats, MYB binding site (MBS), and TCA-elements. An analysis of AaICS1 transcript levels in multifarious tissues of A. annua using quantitative real-time polymerase chain reaction (qRT-PCR) showed that old leaves had the highest transcription levels. AaICS1 was up-regulated under wounding, drought, salinity, and SA treatments. This was corroborated by the presence of the predicted cis-acting elements in the promoter region of AaICS1. Overexpressing transgenic plants and RNA interference transgenic lines of AaICS1 were generated and their expression was compared. High-performance liquid chromatography (HPLC) results from leaf tissue of transgenic A. annua showed an increase in artemisinin content in the overexpressing plants. These results confirm that AaICS1 is involved in the isochorismate pathway.

Expansion and Molecular Characterization of AP2/ERF Gene Family in Wheat (Triticum aestivum L.)

“…The RAV subfamily is involved in the signal transduction of ethylene and other plant hormones ( Alonso et al, 2003 ), Brassinosteroid ( Hu et al, 2004 ), and also participated in the water stress tolerance of DREB subfamily members. The DREB genes with a conservative binding sequence CCGAC commonly bind to the main LTR and/or MBS (core sequences: CCGAAA and C/TAACTG) cis -acting elements upstream of the gene and plays a crucial role in resisting biological stress (including cold and drought) effect ( Hogan et al, 2003 ; Wang et al, 2017 ). Additionally, the transcription factors from the ERF subfamily binds with GCC-boxes which are entangled in different pathways of hormone signaling, like ethylene, 2-hydroxybenzoic acid, and jasmonic acid pathways ( Fujimoto et al, 2000 ; Oñate-Sánchez and Singh, 2002 ; Mantiri et al, 2008 ).…”

Genome-Wide Identification of the Q-type C2H2 Transcription Factor Family in Alfalfa (Medicago sativa) and Expression Analysis under Different Abiotic Stresses

“…A previous study confirmed that many important cis -regulatory elements already existed in the promoter regions of stress response genes in MYBs, WRKYs, and MADS-boxes [ 35 , 40 , 46 ]. Furthermore, many of these elements, such as ABREs and DREs, have been reported to widely participate in abiotic stress responses in Artemisia annua , Arabidopsis and wheat [ 47 , 48 , 49 ]. However, no study has investigated these key regulatory elements in alfalfa.…”