Genome wide identification and characterization of Isopentenyl transferase (IPT) gene family associated with cytokinin synthesis in rice

Rice (Oryza sativa L.) is one of the key food crops in ensuring global food security and accounts for nearly one fourth of the world’s total food supply. Rice production is significantly affected by abiotic stresses. Cytokinins (CKs) play a pivotal role in the regulation of the plant growth, development and abiotic stress responses. In present study, genome-wise analysis led to the identification of 10 Isopentenyl transferase (IPT) gene family members, encoding rate-limiting enzymes in CK biosynthesis pathway in rice. Phylogenetic analysis categorized IPTs into four subfamilies that are structurally and functionally conserved across species with similar gene structures, motifs, domains, cis-acting elements were identified. We performed a genome-wide identification of IPT family members from the rice genome, identified their chromosomal location, gene structure, protein properties, cis-element and phylogeny. Further, Real-time PCR analysis was carried out to understand the spatio-temporal and stress responsive expression of IPT gene family members. OsIPT1, OsIPT2, OsIPT4, OsIPT7, OsIPT8 and OsIPT10 showed similar expression level in both root and shoot of seedling or more expression in root, while OsIPT3, OsIPT5, OsIPT6 and OsIPT9 showed higher expression in shoot as compared with root in seedlings. Abiotic stress responsive expression analysis showed that abiotic stresses reduced the expression of all family members except IPT6. Analysis of expression of IPTs in rice cv. Kitaake (low biomass and low yielding) and Taipei (high biomass and high yielding) showed that expression of IPTs were higher in different tissues in Taipei. Present study has also elaborately described the tissue and stage specific expression and for further analysis of IPT in the regulation of biotic and abiotic stress resistance, growth, and development in rice, and provides a comprehensive analysis of the OsIPT gene family, including structures and functions.