caa a22 4500 477101763 CHVBK 20180405111544.0 cr unu---uuuuu 170330e19960801xx s 000 0 eng 10.1007/BF00195189 doi (NATIONALLICENCE)springer-10.1007/BF00195189 Photosynthesis in localised regions of oat leaves infected with crown rust ( Puccinia coronata ): quantitative imaging of chlorophyll fluorescence [Elektronische Daten] [Julie Scholes, Stephen Rolfe] Localised changes in photosynthesis in oat leaves infected with the biotrophic rust fungus Puccinia coronata Corda were examined at different stages of disease development by quantitative imaging of chlorophyll fluorescence. Following inoculation of oat leaves with crown rust the rate of whole-leaf gas exchange declined. However, crown rust formed discrete areas of infection which expanded as the disease progressed and these localised regions of infection gave rise to heterogeneous changes in photosynthesis. To quantify these changes, images of chlorophyll fluorescence were taken 5, 8 and 11 d after inoculation and used to calculate images representing two parameters; ΦII, a measure of PSII photochemical efficiency and ΔFm/Fm′, a measure of non-photochemical energy dissipation (qN). Five days after inoculation, disease symptoms appeared as yellow flecks which were correlated with the extent of the fungal mycelium within the leaf. At this stage, ΔII was slightly reduced in the infected regions but, in uninfected regions of the leaf, values of ΦII were similar to those of healthy leaves. In contrast, qN (ΔFm/Fm′) was greatly reduced throughout the infected leaf in comparison to healthy leaves. We suggest that the low value of qN in an infected leaf reflects a high demand for ATP within these leaves. At sporulation, 8 d after inoculation, ΦII was reduced throughout the infected leaf although the reduction was most marked in areas invaded by fungal mycelium. In the infected leaf the pattern of non-photochemical quenching was complex; qN was low within invaded regions, perhaps reflecting high metabolic activity, but was now much higher in uninfected regions of the infected leaf, in comparison to healthy leaves. Eleven days after inoculation "green islands” formed in regions of the leaf associated with the fungal mycelium. At this stage, photosynthesis was severely inhibited over the entire leaf; however, heterogeneity was still apparent. In the region not invaded by the fungal mycelium, ΦII and qN were very low and these regions of the leaf were highly fluorescent, indicating that the photosynthetic apparatus was severely damaged. In the greenisland tissue, ΦII was low but detectable, indicating that some photosynthetic processes were still occurring. Moreover, qN was high and fluorescence low, indicating that the cells in this region were not dead and were capable of significant quenching of chlorophyll fluorescence. Springer-Verlag, 1996 Chlorophyll fluorescence imaging nationallicence Photosynthesis nationallicence Puccinia (crown rust on oats) nationallicence Leaf (pathogen, green island) nationallicence ΦII : photochemical efficiency of photosystem II nationallicence qN : non-photochemical energy quenching nationallicence AFm/Fm′ : a measure of qN nationallicence dai : days after inoculation nationallicence IRGA : infra-red gas analyser nationallicence Scholes Julie Robert Hill Institute, Department of Animal and Plant Sciences, University of Sheffield, S10 2TN, Sheffield, UK aut Rolfe Stephen Robert Hill Institute, Department of Animal and Plant Sciences, University of Sheffield, S10 2TN, Sheffield, UK aut Planta Springer-Verlag 199/4(1996-08-01), 573-582 0032-0935 199:4<573 1996 199 425 https://doi.org/10.1007/BF00195189 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/BF00195189 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Scholes Julie Robert Hill Institute, Department of Animal and Plant Sciences, University of Sheffield, S10 2TN, Sheffield, UK aut NATIONALLICENCE 700 1- Rolfe Stephen Robert Hill Institute, Department of Animal and Plant Sciences, University of Sheffield, S10 2TN, Sheffield, UK aut NATIONALLICENCE 773 0- Planta Springer-Verlag 199/4(1996-08-01), 573-582 0032-0935 199:4<573 1996 199 425 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer