International Network of Plant Abiotic Stress

Grantee : Anamika Mishra (PhD Student), Institute of Physical biology, University of South Bohemia (CZ)

amishra@greentech.cz

Hosts: Prof. Dr. Arnd G. Heyer

Biologisches Institut, Abt. Botanik, Universität Stuttgart, Pfaffenwaldring 57, D-70550, Stuttgart, Germany

arnd.heyer@bio.uni-stuttgart.de

Duration: 06.01.10- 24.01.10

Motivation & Objectives:

Precise methods for quantification of frost tolerance and strategies for the screening large populations of plants are necessary to define the underlying genetic determinants, but currently efficient screening methods are not available. The standard method for measuring freezing tolerance, the electrolyte leakage assay, is very laborious and therefore not easily applicable for large scale screening purposes. We started this scientific collaboration through STSM program of the European COST project to test the possibility of the existing chlorophyll fluorescence imaging technique to determine cold tolerance in Arabidopsis accessions. 

Main Results

We recorded time – resolved chlorophyll fluorescence images of nine Arabidopsis thaliana accessions originating from different habitats and displaying large variation in freezing tolerance and cold acclimation capacity. The key fluorescence parameters, e.g., maximum quantum efficiency of PSII photochemistry (Qy=Fv/Fm), plant vitality index (Rfd), photochemical (qP) and non-photochemical quenching (NPQ) have been calculated for both the AC (acclimated) and NAC (non acclimated) state of the nine Arabidopsis thaliana accessions. Preliminary results indicate that maximum quantum yield of PSII photochemistry (Fv/Fm) can quantify the cold tolerance of the Arabidopsis accessions. Other classical fluorescence parameters e.g. F₀, NPQ, Rfd, Fs/F₀ were also able to discriminate the most sensitive and most tolerant species; however, none of them clearly discriminated accessions showing smaller differences in freezing tolerance. The experiments suggest that the chlorophyll fluorescence imaging can probably be used as an alternative method to accurately determine the freezing tolerance. We still need to perform additional sets of experiment with whole plants to find out the most sensitive parameter that could potentially be used for large scale screening and open new ways to explain the molecular basis of plant cold acclimation.

Future collaborations with the host: We have started another collaborative project aiming to investigate the phenotype of a raffinose knockout mutant. Another interesting project will be to evaluate the possibility to use whole plant instead of detached leaf chlorophyll fluorescence imaging for investigating freezing tolerance of Arabidopsis accessions as it was done in the current experiment.

Acknowledgements:

I would like to give my special thanks to the European COST project FA0605 for the financial support of my scientific stay in Stuttgart, Germany. The proposed STSM was successfully carried-out and the anticipated intentions are fulfilled. I would like to give thank to the host and everyone who took part in this collaborative experiments.