Characterization of the role of OsAP2_40 in Arabidopsis and rice root

Abstract

Plants are non-mobile living organisms and withstand with many diversified natural conditions. The root architect and its plasticity have an important role for plant survival in many abiotic and biotic stress conditions. After the convergent evolution of roots, in different taxa, the roots system varies according to the need. Crown roots form a major root system of the rice plant during later stages of plant development and help the plant to adapt to flood and hypoxia conditions. Deciphering the regulatory interactions of crown root formation might help in manipulating rice architecture to increase grain yields. Auxin signalling plays an important role at different stages of crown root formation. Auxin regulates the expression of a lateral organ boundary domain (LBD) protein, CRL1 (CROWN ROOTLESS 1), which further regulates the AP2/ERF coding gene TOC168/OsAP2_40 and increases the crown root primordia. This dissertation focuses on characterizing the role OsAP2_40 in rice by raising OsAP2_40 promoter-reporter transgenic lines. The new protocol adapted from (Toki et al. 1997) was employed to generate transgenic lines. This is a modified protocol having an optimized proportion of growth factors, gelling agent, and incubation period. This method was found to be efficient, less tedious with the high efficiency of transformant generation. We further aim to study the divergence in the role of OsAP2_40 during evolution from dicot to monocots, by constitutively expressing the OsAP2_40 gene under the Arabidopsis promoter in Arabidopsis mutants. The final aim was to learn molecular biology tools and techniques. In the molecular study, I learned the isolation and estimation of genomic DNA/RNA, PCR amplification, Restriction digestion, carried out agarose gel electrophoresis. In addition, I learned microbial techniques such as isolation and identification of antibiotic-sensitive bacteria, plasmid isolation from microbial strains, and transformation. I also gained knowledge about bioinformatics and computer skills of BLAST, primer designing using NCBI and other web-based bioinformatics tools. Study of loss of function mutants has enhanced our knowledge of the complex mechanism of root development. Therefore, we designed primers for miRNA for the OsAP2_AK gene. Due to the high functional redundancy of OsPLTs, we designed miRNA to target OsAP2_AK and phylogenetically its nearest relative gene (OsOSPLT4) in rice.