Identification and Expression Pattern of the KNOX Gene Family in Polygala tenuifolia
XU Sheng1, QIAO Xiao-Yu1, ZONG Hao-Ran1, TONG Xu-Yao1, WEI Shu-Shen1, CUI Jia-Jun1, YAN Yong-Gang1, ZHANG Gang1, YANG Bing-Yue1, PENG Liang1,2,*
1 School of Pharmacy/Shaanxi Engineering Research Center for Application and Development of Qinling Chinese Herbal Medicine/Key Laboratory of "Qin Medicine" Research and Development, Shaanxi University of Chinese Medicine, Xi'an 712046, China; 2 State Key Laboratory for Quality Ensurance and Sustainable Use of Dao-di Herbs, Shaanxi University of Chinese Medicine, Xi'an 712046, China
Abstract：The KNOX transcription factor family is an important class of plant homeodomain proteins that play key regulatory roles in plant growth, development, and stress responses. This study aimed to identify and characterize the KNOX gene family members in Polygala tenuifolia, and to explore their tissue-specific expression patterns as well as their response characteristics to biotic and abiotic stresses. Using bioinformatics approaches, KNOX family genes were screened and identified based on the whole-genome sequence of P. tenuifolia, and their physicochemical properties, gene structures, conserved motifs, and promoter cis-regulatory elements were analyzed. Synteny analyses were performed both intra- and inter specifically. A phylogenetic tree was constructed using MEGA 7.0 software, and the expression profiles of KNOX genes in different tissues (roots, stems, and leaves) as well as under salt and salicylic acid (SA) stresses were examined by qPCR. The results showed that a total of 16 KNOX gene family members were identified in P. tenuifolia, distributed across 12 chromosomes, with 13 pairs of PtKNOX genes exhibiting syntenic relationships. Phylogenetic analysis classified the KNOX genes into 2 major groups: ClassI and ClassⅡ. Tissue-specific expression analysis revealed that different types of KNOX genes exhibited distinct expression patterns across various tissues and organs. qPCR results demonstrated that both salt stress and SA treatment significantly upregulated the expression levels of Pt01c1792.1 and Pt17c1863.1 (P<0.05). This study provides a theoretical basis for further investigations into the biological functions of PtKNOX genes in regulating growth, development, and secondary metabolite biosynthesis in P. tenuifolia.
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