Identification and expression analysis of pathogenesis-related proteins 1 family genes in Aquilaria sinensis

Pathogenesis related protein 1 (PR1) plays an important role in plant resistance to stress and growth and development. This study identified and systematically analyzed 8 AsPR1 genes in Aquilaria sinensis using bioinformatics methods. The predicted molecular weight of encoded AsPR1 proteins is between 12.95 kD and 43.41 kD. The two-dimensional structure and conserved motif analysis of the AsPR1 proteins demonstrated that the similarity of 8 AsPR1 proteins was 51.38%, and all 8 AsPR1 proteins had conserved CAP-PR1 domains. Cis-acting elements analysis showed that the AsPR1 gene family proteins have cis-acting elements that respond to plant hormones, abiotic stress, and biological processes. Chromosomal mapping showed that the AsPR1 gene was distributed on chromosomes 1, 3, 4 and 8. The full-length AsPR1-4 sequence was successfully cloned according to the transcriptome sequencing analysis from A. sinensis, which contains a 516 bp ORF that encodes 171 amino acids. Furthermore, we successfully expressed AsPR1-4-GST fusion protein. The subcellular localization experiments indicated that AsPR1-4 is located in the cytoplasm and chloroplast. The real-time fluorescence quantitative PCR results showed that AsPR1-4 had the highest expression level in stems, followed by roots, and the lowest expression level in leaves. Exogenous MeJA and SA significantly increased the expression of AsPR1-4 in Calli. Additionally, the transcripts level of AsPR1-4 remarkably decreased under four abiotic stresses, including salt, low temperature, heavy metals, and drought stress. This study lays the foundation for further elucidating the function of PR1 protein in the defense response of A. sinensis and its application in agarwood production.