Identification Of Low Nitrogen Stress Induced Genes And Expression Analysis Of The Thioredoxin Protein Gene Family In Rice (Oryza Sativa L.)

Nitrogen has traditionally been considered one of the most important plant nutrients. In the plant system, this cycle is very complex and involved many enzymes. Increasing the efficiency of these enzymes is one of the better ways to increase the nitrogen use efficiency (NUE) of the plant system. For this purpose in the present study 12 candidate genes induced by low nitrogen stress were studied for their function in the nitrogen metabolism or related cycle in the plants by overexpressing and gene silencing and also checking the T-DNA insertion mutants of the candidate genes. Overexpressed, silenced transgenic plants and mutant lines were not showed any kind of visible phenotypic changes under normal and low nitrogen stress conditions in the hydroponic culture and field condition. Promoter analysis, GFP expression of the candidate genes were observed in the different tissues of plant life cycles.Thioredoxin (Trx) proteins play important biological functions in cells by changing redox via thioldisulfied exchange. This system is specifically widespread in plants. Through database search, 30 potential Trx protein-encoding genes (OsTrx) identified in rice (Oryza sativa L.). Analysis of the complete set of OsTrx proteins are presented here, including chromosomal location, conserved motifs, domain duplication, and phylogenetic relationship. Number of more introns in OsTrx5 suggested the origin of Trx gene.A comprehensive expression profile of Trx genes family was investigated by analyzing the signal data of this family extracted from the whole genome microarray analysis of Minghui63 and Zhenshan97, two indica parents, and the hybrid of these two parents Shanyou63, using 27 different tissues representing the entire life cycle of rice. Results revealed specific expression of some members at germination transition as well as 3-leaf stage during the vegetative growth phase of rice. OsTrx genes are also found to be differentially up- or down-regulated in rice seedlings subjected to treatments of phytohormones and light/dark conditions. The expression levels of the OsTrx genes in the different tissues and under different treatments were also checked by RT-PCR analysis. The identification of OsTrx genes showing differential expression in specific tissues among different genotypes or under different environmental cues could provide a new avenue for functional analyses in rice.