Abstract
[Truncated abstract] Salicylic acid (SA) is a known signalling molecule that alters plant responses to pathogen infection by inducing systemic acquired resistance (SAR) via expression of pathogen-related genes. Apart from biotic stresses, SA also plays a key role in plant adaptive responses to various abiotic stresses such as salinity, oxidative stress, ozone exposure, UV radiation, heavy metals, osmotic stress, high temperatures, chilling and drought stresses. However, mechanisms of SA involvement in plant tolerance to abiotic stresses are yet to be identified. A role of SA in regulation of ion transport processes in plants during salt stress has largely been ignored. Also, no study attempted to distinguish the effects of exogenous and endogenous SA on plant responses to salt stress. Arabidopsis thaliana transgenic plants with modifications in SA signalling are the perfect models for deciphering SA action in signalling and effects on ion transporters under salt stress.
Non-invasive ion-selective microelectrode measurements (using the MIFE® system) have elucidated adaptive responses of plants to a large number of abiotic stresses including salinity. However, the practical application of this technique in Na+ flux measurements was severely limited by insufficient selectivity of commerciallyavailable Na+ ionophores/cocktails. They could not distinguish between Na+ and other interfering ions such as K+ and Ca2+, causing incorrect measurements of Na+ concentration and therefore Na+ fluxes. To overcome this limitation, a calixarene-based Na+ cocktail was developed. This cocktail demonstrated high selectivity for Na+ against K+ and Ca2+. The cocktail was tested for measurements of Na+ fluxes at the root surface of Arabidopsis plants. For the first time, the initial (0-15 min) large Na+ influx followed by small Na+ influx (15-45 min) was demonstrated when plants were exposed to acute salt stress. This latter Na+ influx could not be shown with the commercially-available Na+ cocktail due to (i) its low selectivity against K+; (ii) and high K+ efflux during the first minutes of salt stress.
Non-invasive ion-selective microelectrode measurements (using the MIFE® system) have elucidated adaptive responses of plants to a large number of abiotic stresses including salinity. However, the practical application of this technique in Na+ flux measurements was severely limited by insufficient selectivity of commerciallyavailable Na+ ionophores/cocktails. They could not distinguish between Na+ and other interfering ions such as K+ and Ca2+, causing incorrect measurements of Na+ concentration and therefore Na+ fluxes. To overcome this limitation, a calixarene-based Na+ cocktail was developed. This cocktail demonstrated high selectivity for Na+ against K+ and Ca2+. The cocktail was tested for measurements of Na+ fluxes at the root surface of Arabidopsis plants. For the first time, the initial (0-15 min) large Na+ influx followed by small Na+ influx (15-45 min) was demonstrated when plants were exposed to acute salt stress. This latter Na+ influx could not be shown with the commercially-available Na+ cocktail due to (i) its low selectivity against K+; (ii) and high K+ efflux during the first minutes of salt stress.
| Original language | English |
|---|---|
| Qualification | Doctor of Philosophy |
| Publication status | Unpublished - 2014 |