Figure 1 - uploaded by Zoltán Árpád Nagy
Content may be subject to copyright.
Leaf necrosis on Nicotiana tabacum cv. Xanthi nc leaves after challenge inoculation. (A): control, (B): SAR, (C): the plants were not inoculated with TMV, but their leaves were removed after 4 days (LR4), (D): the four inoculated leaves were removed from the plants 4 days after inoculation (LR4+TMV). Bar: 3 cm. Red circles on (A) mark the proc‐ essed lesions during image analysis.
Source publication
Nicotiana tabacum L. cv. Xanthi nc plants were inoculated with tobacco mosaic virus (TMV) in order to develop a method for evaluation of lesion size and its distribution characteristics during the induction of systemic acquired resistance (SAR). All necrotic le‐ sions were scored with an image analysis software and subjected to statistical analysis...
Contexts in source publication
Context 1
... all lesions per leaf resulted in more accurate estimation of lesion size compared to former approaches [7,12,13]. Figure 1 demonstrates this process on TMV-infected tobacco leaves. ...
Context 2
... from Figs. 2, 3 and 4 are based on one representative experiment (Table 1) and serve as an example of three separate experiments. Mock inoculation with abrasive had no effect on lesion diameter and its distribution compared to control plants (Figs. 2, 3A, B and 4A, B). Induction of SAR was clearly manifested in differences of lesion development ( Fig. 1) and in lesion size (Fig. 2) 4 days after challenge inoculation in all experiments. Although in control plants no significant differences were found between 5th and 6th leaf levels (Fig. 2), induction of SAR caused significant differences in degree of diminishing TMV lesion size between the 5th and 6th leaf levels. The effect of SAR ...
Context 3
... did not result in a significant shift in lesion Figure 3. Kernel density estimation of TMV lesion size distribution on Nicotiana tabacum cv. Xanthi nc leaves at leaf level 5 (upper panel, A) and 6 (lower panel, B) after induction of systemic acquired resistance (SAR). For abbreviations and explanations of treatments see Fig. 2. development (LR4, Figs. 1 and 2, Table 1). Moreover, distribution of lesion sizes showed a plateau-like picture, comparable to control leaves (Fig. 3). Simultaneous comparison of treatments also showed that LR4 treated plants did not significantly differ from control plants at least on the 6th leaf level (p = 0.3500 with confidence interval: [-0.0353; 0.1805], Fig. ...
Context 4
... the contrary, removal of TMV-infected leaves after 4 days (LR4+TMV) mimicked the development of SAR in all characteristics in all three experiments. Lesion development was considerably, about 50% inhibited (Figs. 1, 2 and Table 1). The statistical analysis of data clearly showed highly significant differences between LR4+TMV and control plants (p < 0.001 for both leaf levels) but no significant differences between LR4+TMV and SAR treatments at both leaf levels (Fig. 4A, B). ...
Citations
... Plants with induced SAR exhibit a higher level of resistance upon subsequent infections, in comparison to the native plants (Ross 1961;Sticher et al. 1997;Shah 2009). The SAR is a well-recognized strategy to control plant pathogens because of its evolutionary stability, long-lasting effectiveness and putative trans-generational effect (Nagy et al. 2016). Experiments suggest that mobile signals prime the SAR-induced plants to activate faster and elevate transcription of defense-related genes during subsequent infections (Fu and Dong 2013; Xin and He 2013). ...
Harnessing the phytomicrobiome offers a great opportunity to improve plant productivity and quality of food. In the recent past, several phytomicrobiome microbes have been explored for their potential involvement in increasing crop yield. This review strategically targets to harness the various dimensions of phytomicrobiome for biotic stress management of crop plants. The tripartite interaction involving plant-microbiome-pathogen has been discussed. Positive interventions in this system so as to achieve disease tolerant plants has been forayed upon. The different signalling molecules sent out by interacting partners of phytomicrobiome have also been analysed. The novel concept of artificial microbial consortium in mitigation of pathogenic stress has also been touched upon. The aim of this review is to explore the hidden potential of phytomicrobiome diversity as a potent tool against phytopathogens, thereby improving crop health and productivity in a sustainable way.
... However, considering recent data about multiple signal mechanisms with diverse chemical substances described mainly in Arabidopsis-bacteria plant-pathogen systems it is reasonable to test whether this multiple signalling is due to environmental or some other circumstantial factors. It is especially true for tobacco where less experimental data is available and a virus-inducible SAR response could be also studied by using a computer-assisted method for symptoms evaluation and statistical analysis [28,[30][31][32]. ...
... Xanthi nc) [31]. Former results indicated that signal transduction from inducing leaves into distant ones is fully completed within 4 days after primary TMV inoculation [28,30]. Therefore, phloem sap was collected in this time window (2 or 3 days after inoculation) for 24 h from TMV-infected and control leaves. ...
Systemic acquired resistance (SAR) is a defence mechanism that induces protection against a wide range of pathogens in distant, pathogen-free parts of plants after a primary inoculation. Multiple mobile compounds were identified as putative SAR signals or important factors for influencing movement of SAR signalling elements in Arabidopsis and tobacco. These include compounds with very different chemical structures like lipid transfer protein DIR1 (DEFECTIVE IN INDUCED RESISTANCE1), methyl salicylate (MeSA), dehydroabietinal (DA), azelaic acid (AzA), glycerol-3-phosphate dependent factor (G3P) and the lysine catabolite pipecolic acid (Pip). Genetic studies with different SAR-deficient mutants and silenced lines support the idea that some of these compounds (MeSA, DIR1 and G3P) are activated only when SAR is induced in darkness. In addition, although AzA doubled in phloem exudate of tobacco mosaic virus (TMV) infected tobacco leaves, external AzA treatment could not induce resistance neither to viral nor bacterial pathogens, independent of light conditions. Besides light intensity and timing of light exposition after primary inoculation, spectral distribution of light could also influence the SAR induction capacity. Recent data indicated that TMV and CMV (cucumber mosaic virus) infection in tobacco, like bacteria in Arabidopsis, caused massive accumulation of Pip. Treatment of tobacco leaves with Pip in the light, caused a drastic and significant local and systemic decrease in lesion size of TMV infection. Moreover, two very recent papers, added in proof, demonstrated the role of FMO1 (FLAVIN-DEPENDENT-MONOOXYGENASE1) in conversion of Pip to N-hydroxypipecolic acid (NHP). NHP systemically accumulates after microbial attack and acts as a potent inducer of plant immunity to bacterial and oomycete pathogens in Arabidopsis. These results argue for the pivotal role of Pip and NHP as an important signal compound of SAR response in different plants against different pathogens.
... The spectral range from 200 nm to 1015 nm with a spectral resolution of 0.327 nm was measured. Stastistical analysis TMV lesion development was evaluated with ImageJ 1.48v analysis software as described earlier (Nagy et al., 2016;Nagy et al., 2017). Statistical calculations were carried out with R (R CoreTeam, 2015). ...
... On the other hand, experiments with tobacco draw the attention to optimized growth of plants that could be a more difficult problem with rosette-shaped plants. Therefore, in addition to exact detection and comparison of symptoms' expression after SAR induction (Nagy et al., 2016Nagy et al., , 2017), optimization of the effect of artificial light sources is also an important factor in experimental design studying SAR. xx for plant growth tests. ...
Our and literature studies indicated that systemic acquired resistance (SAR) is effectively inducible in greenhouse, and certain artificial light sources cause non-optimal growth of tobacco plants. Therefore, the morphological characteristics, local and systemic resistance response of N. tabacum cv. 'Xanthi' nc plants (harbouring NN resistance genes) to tobacco mosaic virus (TMV) infection under three artificial light sources with different spectral distribution were compared with greenhouse conditions. Statistical analysis of data was carried out by R package (R Core Team, 2015). Generally, artificial light sources (especially fluorescent tube and halogen lamp) decreased the local resistance response and caused substantial morphological and developmental differences as compared to greenhouse conditions when plants were kept during their entire life (lifelong experimental regime) under these conditions. On the contrary, no or much less differences were found when plants were transferred from greenhouse to artificial light sources only at six leaf stage (short experimental regime). While induction of SAR frequently decreased TMV lesion size by about 50-60% under greenhouse conditions, two of the three artificial light sources, fluorescent tube and halogen lamp were substantially and significantly less effective under short experimental regime conditions (25-35%). A metal halide light source with similarity to sunshine's spectral distribution, however, partially mimicked the effect of greenhouse conditions indicating the importance of light spectrum among other factors in SAR induction and prevention of distorted growth of plants. Consequently, the optimization of the effect of artificial light sources is an important factor in experimental design studying signal transduction and biochemistry of SAR.
Harnessing the phytomicrobiome offers a great opportunity to improve plant productivity and quality of food. In the recent past, several phytomicrobiome microbes have been explored for their potential involvement in increasing crop yield. This review strategically targets to harness the various dimensions of phytomicrobiome for biotic stress management of crop plants. The tripartite interaction involving plant- microbiome-pathogen has been discussed. Positive interventions in this system so as to achieve disease tolerant plants has been forayed upon. The different signalling molecules sent out by interacting partners of phytomicrobiome have also been analysed. The novel concept of artificial microbial consortium in mitigation of pathogenic stress has also been touched upon. The aim of this review is to explore the hidden potential of phytomicrobiome diversity as a potent tool against phytopathogens, thereby improving crop health and productivity in a sustainable way.
Local and systemic effects of azelaic acid (AzA) pretreatments on local necrotic lesion formation induced by Tobacco mosaic virus (TMV) were studied in Nicotiana tabacum cv. Xanthi nc plants as measured by a semi-automated, computer-assisted method. Local application of AzA (0.2–1.0 mM) showed no or limited influence (either increase or decrease) on lesion size of TMV-inoculated leaves. In addition, AzA pretreatment did not modify the multiplication of TMV detected by semiquantitative RT-PCR. No significant systemic effect of AzA on lesion size of TMV was detectable in distant leaves. Moreover, AzA treatment had no considerable local and systemic effect on symptom expression and multiplication of incompatible (P. syringae pv. tomato DC3000) and compatible (P. syringae pv. tabaci) bacteria. The response of the viral and bacterial pathogens to AzA was not different if tobacco plants were exposed to light or darkness after AzA treatment. However, the amount of AzA, measured by HPLC–MS, was doubled in phloem exudates of TMV infected leaves as compared to the control leaves, but concentrated exudates containing AzA did not induce local resistance response. In addition, the amounts of two other short-chain dicarboxylic acids (suberic acid and sebacic acid) increased in phloem exudates of virus-infected leaves. All these results suggest that, at least in tobacco, AzA does not induce considerable local or systemic effects on viral and bacterial infections. Therefore, its formerly reported role in signal transduction and/or induction of systemic acquired resistance (SAR) in Arabidopsis cannot be confirmed in tobacco.
This paper reviews the extended and contradictory literaure of systemic acquired resistance
(SAR). Compounds of signal transduction pathway(s) and the effect of light on signalling are
discussed in more details. Besides these features historical, practical and methodological aspects are
also covered. Our results on digital imaging method, as a new way of evaluating disease symptoms,
and determination of timing of signal transduction during SAR are presented in the tobacco mosaic
virus (TMV)–tobacco model system.
