Transcriptome analysis of drought induced systemic tolerance in rice (Oryza sativa L) medicated by plant growth promoting rhizobateria
Loading...
Files
Date
2012
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Department of plant biotechnology, College of horticulture, Vellanikkara
Abstract
Plant-growth-promoting rhizobacteria (PGPR) are associated with plant roots and augment plant productivity and immunity; however, recent work by several groups shows that PGPR also elicit so-called ‘induced systemic tolerance’ to salt and drought. Some PGPR also elicit physical or chemical changes related to plant defense, a process referred to as ‘induced systemic resistance’ (ISR). ISR elicited by PGPR has suppressed plant diseases caused by a range of pathogens in both the greenhouse and field . However, fewer reports have been published on PGPR as elicitors of tolerance to abiotic stresses, such as drought, salt and nutrient deficiency or excess (Yang et al., 2009) . The present study on “ Transcriptome analysis of drought induced systemic tolerance in rice mediated by plant growth promoting rhizobacteria “ was undertaken at the Centre for Plant Biotechnology and Molecular Biology, College of Horticulture, Vellanikkara during the period 2010-2012 with the objective to identify the differentially expressed genes and signal tranduction pathways operating in rice (Oryza sativa.L) during water stress conditions mediated by plant growth promoting bacteria. The Mattathriveni, a popular rice variety of Kerala which is susceptible to drought was used as the experimental material as its performance in upland is also very poor. The pot experiment was carried out under water logged condition and three treatments were given. In T1, control plants were maintained in water logged condition, in T2 water was with held for 48 hours and in T3 plants which were treated with Psedomonas fluorescens Pf 1 (KAU strain) water was with held for 48 hours. Observations on biometric and physiological parameters were taken. The physiological parameters were taken using Infra red gas analyzer. Enhanced growth promotional effect and photosynthetic efficiency was noticed in Pf treated plants. Also plants maintained lower leaf temperature and lower stomatal conductance in Pf treated stressed plants which is a water saving mechanism to cope up with water stress. The mechanisms for abiotic stress tolerance are based on activation and regulation of specific set of stress-related genes which are involved in signaling, transcriptional control, and protection of membranes and proteins. The technique used to analyse the transcriptome was the differential display-RTPCR allows extensive analysis of gene expression among several cell populations (Sturtevant, 2000). The gene expression analyses requires good quality RNA which was isolated by Trizol reagent method with utmost care to prevent its degradation by nucleases. About 1μg of total RNA from all the treatments were taken for DD-RT-PCR analysis. The first strand cDNA was synthesized from the above RNA samples using HT11C (AAGCTTTTTTTTTTTC). Each first strand cDNA was used for the second strand amplification with 8 different arbitrary primers. The PCR product was resolved on 6% denaturing urea polyacrylamide gels and visualized after silver staining. Tthe gel was dried overnight for elution and further analysis. The up regulated ,down regulated and differentially expressed cDNA fragments were retrived from the gel and reamplified with the same set of primers as in the initial DD-RT-PCR reaction and analyzed electrophoretically. The agarose gel electrophoresis showed that the transcript derived fragments(TDFs) obtained were relatively short (150-700bp). TDFs were cloned. The vector used was pJET which used less ligation time and gave only white colonies of recombinants. The clones were sequenced at Sci Genome Cochin. The sequence data obtained were analysed by in silico tools. The sequence from differentially expressed TDFs showed homology to SOS1 regulatory proteins which is involed in ion homeostasis in abiotic stress signaling which is salint finding. The other major genes identified were cytochrome oxidase, ATP synthase, heat shock proteins, MYB transcription factor which are all operating in major signal transduction pathways. The gene expression were confirmed by e Northern analysis, which is an in silico tool to validate the gene expression during abiotic and biotic stress related studies by comparing with the Arabidopsis gene expression data base available at Botany array resources.
Description
PG
Keywords
null