Seeing 'cool' and 'hot'--infrared thermography as a tool for non-invasive, high-throughput screening of Arabidopsis guard cell signalling mutants.
ABSTRACT The use of Arabidopsis mutants defective in abscisic acid (ABA) perception has been instrumental in the understanding of stomatal function, in particular, ABA signalling in guard cells. The considerable attention devoted to ABA signalling in guard cells is due in part to (1) the fundamental role of ABA in drought stress and (2) the use of a screening protocol based on the sensitivity of seed germination to ABA. Such a screen has facilitated the isolation of ABA signalling mutants with genetic lesions that exert pleiotropic effects at the whole plant level. As such, there is a requirement for new approaches to complement the seed germination screen. The recent advances made in the use of infrared thermography as a non-invasive, high-throughput tool are reviewed here and the versatility of this technique for screening Arabidopsis defective in stomatal regulation is highlighted.
Article: Restricted transpiration may not result in improved drought tolerance in a competitive environment for water[show abstract] [hide abstract]
ABSTRACT: We have investigated how mutants with enhanced stomatal closure behave in a competitive situation with wild type plants for water. The abscisic acid oversensitive cbp20 and era1 Arabidopsis mutants retain more water when subjected to limited water supply due to restricted gas exchange, resulting in improved drought tolerance. This phenotype, however, was greatly reduced or disappeared when the root systems of neighboring wild type Arabidopsis plants competed for water in the soil around the mutants. These findings have implications in the potential use of this mutant class in agronomy as well as in designing genetic screens for drought tolerance.Plant Science.
Article: New ABA-hypersensitive Arabidopsis mutants are affected in loci mediating responses to water deficit and Dickeya dadantii infection.[show abstract] [hide abstract]
ABSTRACT: On water deficit, abscisic acid (ABA) induces stomata closure to reduce water loss by transpiration. To identify Arabidopsis thaliana mutants which transpire less on drought, infrared thermal imaging of leaf temperature has been used to screen for suppressors of an ABA-deficient mutant (aba3-1) cold-leaf phenotype. Three novel mutants, called hot ABA-deficiency suppressor (has), have been identified with hot-leaf phenotypes in the absence of the aba3 mutation. The defective genes imparted no apparent modification to ABA production on water deficit, were inherited recessively and enhanced ABA responses indicating that the proteins encoded are negative regulators of ABA signalling. All three mutants showed ABA-hypersensitive stomata closure and inhibition of root elongation with little modification of growth and development in non-stressed conditions. The has2 mutant also exhibited increased germination inhibition by ABA, while ABA-inducible gene expression was not modified on dehydration, indicating the mutated gene affects early ABA-signalling responses that do not modify transcript levels. In contrast, weak ABA-hypersensitivity relative to mutant developmental phenotypes suggests that HAS3 regulates drought responses by both ABA-dependent and independent pathways. has1 mutant phenotypes were only apparent on stress or ABA treatments, and included reduced water loss on rapid dehydration. The HAS1 locus thus has the required characteristics for a targeted approach to improving resistance to water deficit. In contrast to has2, has1 exhibited only minor changes in susceptibility to Dickeya dadantii despite similar ABA-hypersensitivity, indicating that crosstalk between ABA responses to this pathogen and drought stress can occur through more than one point in the signalling pathway.PLoS ONE 01/2011; 6(5):e20243. · 4.09 Impact Factor