Informations et ressources scientifiques
sur le développement des zones arides et semi-arides

Accueil du site → Doctorat → Inde → 2008 → Discovery and validation of single nucleotide polymorphisms in candidate genes of drought tolerance in rice

University of Hyderabad (2008)

Discovery and validation of single nucleotide polymorphisms in candidate genes of drought tolerance in rice

Lachagari, Vijaya Bhasker Reddy

Titre : Discovery and validation of single nucleotide polymorphisms in candidate genes of drought tolerance in rice

Auteur : Lachagari, Vijaya Bhasker Reddy

Université de soutenance : University of Hyderabad

Grade : Doctor of Philosophy (PhD) 2008

Sommaire partiel
The main objective of the present study was to identify the genes involved in drought stress response process, and to dissect these regions to find single nucleotide polymorphisms (SNPs) having correlation with drought tolerance, and converting them in to molecular markers to facilitate marker assisted selection (MAS). As the trait is multigenic showing a complex regulation, our main objective is to identify the genomic regions involved in drought stress response from 430 MB of the rice genome. Various strategies have been employed in the present study to identify the target genomic regions which include construction of subtractive cDNA libraries, analysis of microarray gene expression profiles at various water stress regimes, and comparative analysis of ESTs generated from drought stressed normalized cDNA libraries with reported microarray data besides extensive literature survey. Two rice genotypes having a contrasting phenotype with reference to drought tolerance were selected to identify differentially expressed genes. A highly drought tolerant genotype, Nerica-1 and a drought susceptible genotype (IR64) were used for subtractive cDNA library construction. ESTs generated from this library were deposited in the dbEST division of NCBI. Forty two unigenes involved in various stress response processes such as signal perception, signal transduction, transcription activation and downstream genes involved in stress response were identified besides some novel genes. The variation observed in respect to gene expression between these genotypes is attributed to the variations in the promoter regions, particularly in the regulatory elements which drive the gene expression. In addition, gene expression profiles of ESTs characterized from normalized cDNA library constructed from drought stressed seedlings of Nagina22 genotype were considered. Some of the interesting genes from the gene clusters showing dramatic changes at various time course experiments in three different drought stress regimes at various developmental stages were considered as the drought stress response genes. In addition, some members of interesting gene families identified from the comparative analysis of Nagina22 ESTs with the microarray gene expression profiles of orthologous genes were also considered for the study. The gene regulation observed to be complex under defined stresses condition, particularly, negative regulation of many genes and subsequent triggering/suppressing of other genes is one of the critical areas to understand the mechanism behind such regulation. This kind of regulation is mainly attributed to the involvement of small non-protein coding mRNAs called miRNAs. In order to characterize the regulatory switches triggering biogenesis of such miRNAs, the regions involved in encoding miRNAs and their biogenesis were considered. Besides, some of the reported drought responsive genes were also considered with a major focus on identifying SNPs in the regulatory regions of the targeted regions.

Mots clés : Discovery Nucleotide Polymorphisms Tolerance

Présentation et version intégrale

Page publiée le 16 septembre 2016, mise à jour le 31 janvier 2021