Imaging photosynthesis in wounded leaves of Arabidopsis thaliana

Citation

Quilliam R, Swarbrick PJ, Scholes JD & Rolfe SA (2006) Imaging photosynthesis in wounded leaves of Arabidopsis thaliana. Journal of Experimental Botany, 57 (1), pp. 55-69. https://doi.org/10.1093/jxb/erj039

Abstract
Chlorophyll fluorescence imaging provides a non-invasive and non-destructive means with which to measure photosynthesis. This technique has been used, in combination with 14CO2 feeding, to study the spatial and temporal changes in source-sink relationships which occur in mechanically wounded leaves of Arabidopsis thaliana. Twenty-four hours after wounding, cells proximal to the wound margin showed a rapid induction of ΦII upon illumination (a measure of the efficiency of photosystem II photochemistry) whilst cells more distal to the wound margin exhibited a much slower induction of ΦII and a large, transient increase in NPQ (a measure of the rate constant for non-photochemical energy dissipation within the light-harvesting antenna). These results are indicative of an increase in sink strength in the vicinity of the wound and this was confirmed by the retention of 14C photosynthate in this region. It has been hypothesized that wound-induced cell wall (apoplastic) invertase (cwINV) activity plays a central role in generating localized increases in sink strength in stressed plant tissue and that hexose sugars generated by the sucrolytic activity of cwINV may act as a signal regulating gene expression. Enzyme activity measurements, quantitative RT-PCR, and T-DNA insertional mutagenesis have been used to determine that expression of AtcwINV1 is responsible for all induced cwINV activity in mechanically wounded leaves. Whilst inactivation of this gene abolished wound-induced cwINV activity, it did not affect localized alterations in source-sink relationships of wounded leaves or wound-regulated gene expression. The signals that may regulate source-sink relationships and signalling in wounded leaves are discussed.

Keywords
Arabidopsis thaliana; chlorophyll fluorescence imaging; invertase; photosynthesis; source-sink relationships; sugar signalling; wounding

Journal
Journal of Experimental Botany: Volume 57, Issue 1