Evolutionary variation and expression profiling of Isopentenyl transferase gene family in Arabidopsis thaliana L. and Oryza sativa L.

Cytokinin is widely known for its critical involvement in various processes of plant growth and development, such as cell division, differentiation, and nutrient metabolism. As a phytohormone, it also plays a vital role in the stress modulation mechanism of the plant. Isopentenyl transferase (IPT) is the key regulatory enzyme of cytokinin biosynthesis. In the present study, all the identified members of Arabidopsis and rice IPT family were analyzed in terms of their chromosomal location, exon-intron distribution, and sub-cellular localization. Based on structural variation and evolutionary conservancy, they could be broadly divided into two families- Adenylate IPT and t-RNA IPT. Further, expression of all AtIPT and OsIPT transcripts were analyzed based on publicly available microarray datasets. All AtIPT genes except AtIPT3 and AtIPT6 showed a high level of expression in all the developmental stages of Arabidopsis. Different members of the AtIPT gene family responded differently depending on the type of stress exposure. A high level of expression was observed in the case of OsIPT2 and OsIPT9 in all the developmental stages and tissues of rice, as compared to the other members. In the case of abiotic stresses, OsIPT5 showed significant up-regulation. Transcript abundance of OsIPT2, OsIPT5, OsIPT7-2 and OsIPT9 fluctuated after biotic stress, hormonal imbalance, chemical toxicity, and nutrient deficiency. These members of the OsIPT gene family might be the crucial stress modulators that were validated through semi-quantitative RT-PCR and their role could be explored further for the generation of abiotic stress tolerant plants.