Genome-wide identification and characterization of DIRIGENT gene family (CcDIR) in pigeonpea (Cajanus cajan L.) provide insights on their spatial expression pattern and relevance to stress response

• Published in: Gene 2024-07, Vol.914, p.148417-148417, Article 148417
• Main Authors: Dokka, Narasimham, Tyagi, Shaily, Ramkumar, M.K, Rathinam, Maniraj, Senthil, Kameshwaran, Sreevathsa, Rohini
• Format: Article
• Language: English
• Subjects: Dirigent; Expression; Genome-wide analysis; Pigeonpea; Stress
• ISSN: 0378-1119; 1879-0038
• DOI: 10.1016/j.gene.2024.148417

•An attempt was made to characterize the dirigent (DIR) gene family in Cajanus cajan (pigeonpea).•Twenty-five CcDIRs in pigeonpea were identified by genome-wide identification and divided into six sub-families.•An array of cis-acting elements present in CcDIR promoters might result in discrete expression pattern of CcDIRs during various stresses.•CcDIRs responded to salt, drought, herbivory as well as SA and JA implicating specificity of the genes to stress response. This study is a thorough characterization of pigeonpea dirigent gene (CcDIR) family, an important component of the lignin biosynthesis pathway. Genome-wide analysis identified 25 CcDIR genes followed by a range of analytical approaches employed to unravel their structural and functional characteristics. Structural examination revealed a classic single exon and no intron arrangement in CcDIRs contributing to our understanding on evolutionary dynamics. Phylogenetic analysis elucidated evolutionary relationships among CcDIR genes with six DIR sub-families, while motif distribution analysis displayed and highlighted ten conserved protein motifs in CcDIRs. Promoter analyses of all the dirigent genes detected 18 stress responsive cis-acting elements offering insights into transcriptional regulation. While spatial expression analyses across six plant tissues showed preferential expression of CcDIR genes, exposure to salt (CcDIR2 and CcDIR9) and herbivory (CcDIR1, CcDIR2, CcDIR3 and CcDIR11), demonstrated potential roles of specific DIRs in plant defense. Interestingly, increased gene expression during herbivory, also correlated with increased lignin content authenticating the specific response. Furthermore, exogenous application of stress hormones, SA and MeJA on leaves significantly induced the expression of CcDIRs that responded to herbivory. Taken together, these findings contribute to a comprehensive understanding of CcDIR genes impacting development and stress response in the important legume pigeonpea.