Photosynthesis in localised regions of oat leaves infected with crown rust (Puccinia coronata): quantitative imaging of chlorophyll fluorescence
Photosynthesis in localised regions of oat leaves infected with crown rust (Puccinia coronata): quantitative imaging of chlorophyll fluorescence
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DOI：
10.1007/bf00195189
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发表时间：
1996-08
期刊：
影响因子：
4.3
通讯作者：
J. Scholes;S. Rolfe
中科院分区：
文献类型：
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作者：
J. Scholes;S. Rolfe
利用叶绿素荧光定量成像技术，研究了燕麦叶片感染锈病菌Puccinia coronataCorda后光合作用的变化。燕麦叶片接种冠锈菌后，全叶气体交换速率下降。然而，冠锈病形成离散的感染区域，随着疾病的进展而扩大，这些局部的感染区域引起了光合作用的异质性变化。为了量化这些变化，在接种后5、8和11 d拍摄叶绿素荧光图像，并用于计算代表两个参数的图像：ΦII，PSII光化学效率的度量和ΔFm/Fm′，非光化学能量耗散（qN）的度量。接种后第5天，病害症状表现为黄色絮状物，这与真菌菌丝在叶片内的程度相关。在此阶段，Δ II在受感染的区域略有降低，但在叶片的未受感染的区域，Φ II的值与健康叶片的值相似。相反，qN（ΔFm/Fm′）在整个受感染的叶片中与健康叶片相比大大降低。我们认为，在受感染的叶片中的qN值较低，反映了这些叶片内对ATP的高需求。在孢子形成时，接种后8d，Φ II在整个感染叶中减少，尽管减少在真菌菌丝侵入的区域中最显著。在受感染的叶片的非光化学猝灭的模式是复杂的，qN是低的入侵区域内，也许反映了高代谢活性，但现在高得多，在未受感染的地区的受感染的叶片，相比健康的叶片。接种后11天，在与真菌菌丝体相关的叶片区域形成“绿色岛”。在这个阶段，光合作用被严重抑制整个叶片，但异质性仍然很明显。在未被真菌菌丝侵入的区域，Φ II和qN很低，并且这些区域的叶片荧光很强，表明光合机构受到严重破坏。在绿岛组织中，Φ II很低，但可检测到，表明一些光合作用过程仍在发生。此外，qN高，荧光低，表明该区域的细胞没有死亡，能够显着淬灭叶绿素荧光。
Localised changes in photosynthesis in oat leaves infected with the biotrophic rust fungusPuccinia coronataCorda 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, ΔIIwas slightly reduced in the infected regions but, in uninfected regions of the leaf, values of ΦIIwere 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, ΦIIwas 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, ΦIIand 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, ΦIIwas 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.