Necrotrophic pathogenic bacteria, fungi and oomycetes are widely distributed and are responsible for significant crop losses. Host plants deploy different defense mechanisms and appropriate immune responses to defend them against these pathogens. Regardless of the pathogen’s lifestyle, infection activates plant immune responses either through Pathogen/Microbe Associated Molecular Pattern (P/MAMP) or through Effector Triggered Immunity (ETI). However, as R-genes are not usually associated with resistance to necrotrophs, resistance is largely dependent on the balanced interplay between crucial phytohormones in complex signaling pathways involving jasmonic acid (JA), ethylene, salicylic acid (SA) and abscisic acid (ABA). An increase in salicylic acid levels enhances susceptibility to necrotrophic pathogens but promotes resistance to hemibiotrophs, whereas a deficiency in SA or SA signaling has either no significant impact or affects resistance only at the primary infection site. The same fashion is observed for JA signaling system that appears to elicit resistance against diseases caused by necrotrophic pathogens and can trigger systemic immunity conferring resistance against them. On the other hand, ABA can play a positive or negative role in plant defense responses to necrotrophs as ABA-mediated defense responses are dependent on specific plant-pathogen interactions. Understanding plant immune response against necrotrophic pathogens may lead to the development of resistant or tolerant crop cultivars.
Mengiste, T. (2012) Plant Immunity to Necrotrophs. Annual Review of Phytopathology, 50, 267-294. https://doi.org/10.1146/annurev-phyto-081211-172955
Spanu, P.D. and Panstruga, R. (2017) Editorial: Biotrophic Plant-Microbe Interactions. Frontiers in Plant Science, 8, 192. https://doi.org/10.3389/fpls.2017.00192 https://www.frontiersin.org/article/10.3389/fpls.2017.00192
van Kan, J.A.L. (2006) Licensed to Kill: The Lifestyle of a Necrotrophic Plant Pathogen. Trends in Plant Science, 11, 247-253. https://doi.org/10.1016/j.tplants.2006.03.005
Wei, M., Wang, A., Liu, Y., Ma, L., Niu, X. and Zheng, A. (2020) Identification of the Novel Effector RsIA_NP8 in Rhizoctonia solani AG1 IA That Induces Cell Death and Triggers Defense Responses in Non-Host Plants. Frontiers in Microbiology, 11, 1115. https://doi.org/10.3389/fmicb.2020.01115
Pandey, D., Rajendran, S., Gaur, M., Sajeesh, P.K. and Kumar, A. (2016) Plant Defense Signaling and Responses against Necrotrophic Fungal Pathogens. Journal of Plant Growth Regulation, 35, 1159-1174. https://doi.org/10.1007/s00344-016-9600-7
Laluk, K. and Mengiste, T. (2010) Necrotroph Attacks on Plants: Wanton Destruction or Covert Extortion? The Arabidopsis Book, 8, e0136. https://doi.org/10.1199/tab.0136
Muthamilarasan, M. and Prasad, M. (2013) Plant Innate Immunity: An Updated Insight into Defense Mechanism. Journal of Biosciences, 38, 433-449. https://doi.org/10.1007/s12038-013-9302-2
Pandey, S.P. and Somssich, I.E. (2009) The Role of WRKY Transcription Factors in Plant Immunity. Plant Physiology, 150, 1648-1655. https://doi.org/10.1104/pp.109.138990
Lazniewska, J., Macioszek, V.K., Lawrence, C.B. and Kononowicz, A.K. (2010) Fight to the Death: Arabidopsis thaliana Defense Response to Fungal Necrotrophic Pathogens. Acta Physiologiae Plantarum, 32, 1-10. https://doi.org/10.1007/s11738-009-0372-6
Thomma, B.P.H.J., Nürnberger, T. and Joosten, M.H.A.J. (2011) Of PAMPs and Effectors: The Blurred PTIETI Dichotomy. The Plant Cell, 23, 4-15. https://doi.org/10.1105/tpc.110.082602
Gong, B.-Q., Wang, F.-Z. and Li, J.-F. (2020) Hide-and-Seek: Chitin-Triggered Plant Immunity and Fungal Counterstrategies. Trends in Plant Science, 25, 8. https://doi.org/10.1016/j.tplants.2020.03.006
Wen, L. (2012) Cell Death in Plant Immune Response to Necrotrophs. Journal of Plant Biochemistry & Physiology, 1, 1-3. https://doi.org/10.4172/2329-9029.1000e103
Jones, D.G.J. and Dangl, J.L. (2006) The Plant Immune System. Nature, 444, 323-329. https://doi.org/10.1038/nature05286
Wang, X., Jiang, N., Liu, J., Liu, W. and Wang, G.L. (2014) The Role of Effectors and Host Immunity in Plant-Necrotrophic Fungal Interactions. Virulence, 5, 722-732. https://doi.org/10.4161/viru.29798
Glazebrook, J. (2005) Contrasting Mechanisms of Defense against Biotrophic and Necrotrophic Pathogens. Annual Review of Phytopathology, 43, 205-227. https://doi.org/10.1146/annurev.phyto.43.040204.135923
Coll, N.S., Epple, P. and Dangl, J.L. (2011) Programmed Cell Death in the Plant Immune System. Cell Death & Differentiation, 18, 1247-1256. https://doi.org/10.1038/cdd.2011.37
Yang, G., Tang, L., Gong, Y., Xie, J., Fu, Y., Jiang, D., et al. (2018) A Cerato-Platanin Protein SsCP1 Targets Plant PR1 and Contributes to Virulence of Sclerotinia sclerotiorum. New Phytologist, 217, 739-755. https://doi.org/10.1111/nph.14842
Li, S., Peng, X., Wang, Y., Hua, K. Y., Xing, F., Zheng, Y.Y., et al. (2019) The Effector AGLIP1 in Rhizoctonia solani AG1 IA Triggers Cell Death in Plants and Promotes Disease Development through Inhibiting PAMP-Triggered Immunity in Arabidopsis thaliana. Frontiers in Microbiology, 10, 2228. https://doi.org/10.3389/fmicb.2019.02228
Dolfors, F., Holmquist, L., Dixelius, C. and Tzelepis, G. (2019) A LysM Effector Protein from the Basidiomycete Rhizoctonia solani Contributes to Virulence through Suppression of Chitin Triggered Immunity. Molecular Genetics and Genomics, 294, 1211-1218. https://doi.org/10.1007/s00438-019-01573-9
Anderson, J.P., Sperschneider, J., Win, J., Kidd, B., Yoshida, K., Hane, J., et al. (2017) Comparative Secretome Analysis of Rhizoctonia solani Isolates with Different Host Ranges Reveals Unique Secretomes and Cell Death Inducing Effectors. Scientific Reports, 7, Article No. 10410. https://doi.org/10.1038/s41598-017-10405-y
Checker, V.G., Kushwaha, H.R., Kumari, P. and Yadav, S. (2018) Role of Phytohormones in Plant Defense: Signaling and Cross Talk. In: Singh, A. and Singh, I., Eds., Molecular Aspects of Plant-Pathogen Interaction, Springer, Singapore, 159-184. https://doi.org/10.1007/978-981-10-7371-7_7
Caarls, L., Pieterse, C.M.J. and Van Wees, S.C.M. (2015) How Salicylic Acid Takes Transcriptional Control over Jasmonic Acid Signaling. Frontiers in Plant Science, 6, 170. https://www.frontiersin.org/article/10.3389/fpls.2015.00170 https://doi.org/10.3389/fpls.2015.00170
Wu, Y., Zhang, D., Chu, J.Y., Boyle, P., Wang, Y., Brindle, I.D., De Luca, V. and Després, C. (2012) The Arabidopsis NPR1 Protein Is a Receptor to the Plant Defense Hormone Salicylic Acid. Cell Reports, 1, 639-647. https://doi.org/10.1016/j.celrep.2012.05.008
Jelenska, J., Yao, N., Vinatzer, B.A., Wright, C.M., Brodsky, J.L. and Greenberg, J.T. (2007) AJ Domain Virulence Effector of Pseudomonas syringae Remodels Host Chloroplasts and Suppresses Defenses. Current Biology, 17, 499-508. https://doi.org/10.1016/j.cub.2007.02.028
Zheng, X., Spivey, N.W., Zeng, W., Po-Pu, L., Fu, Z.Q., Klessig, D.F., He, S.Y. and Dong, X. (2012) Coronatine Promotes Pseudomonas syringae Virulence in Plants by Activating a Signaling Cascade That Inhibits Salicylic Acid Accumulation. Cell Host & Microbe, 11, 587-596. https://doi.org/10.1016/j.chom.2012.04.014
Bakker, P., Doornbos, R.F., Zamioudis, C., Berendsen, R.L. and Pieterse, C.M.J. (2013) Induced Systemic Resistance and the Rhizosphere Microbiome. The Plant Pathology Journal, 29, 136-143. https://doi.org/10.5423/PPJ.SI.07.2012.0111
Kravchuk, Z., Vicedo, B., Flors, V., Camańes, G., González-Bosch, C. and Garcia-Agustin, P. (2011) Priming for JA-Dependent Defenses Using Hexanoic Acid Is an Effective Mechanism to Protect Arabidopsis against B. cinerea. Journal of Plant Physiology, 186, 359-366. https://doi.org/10.1016/j.jplph.2010.07.028
Martinez-Medina, A., Fernández, I., Sánchez-Guzmán, M.J., Jung, S.C., Pascual, J.A. and Pozo, M.J. (2013) Deciphering the Hormonal Signalling Network behind the Systemic Resistance Induced by Trichoderma harzianum in Tomato. Frontiers in Plant Science, 4, 206. https://doi.org/10.3389/fpls.2013.00206
Niu, Y., Figueroa, P. and Browse, J. (2011) Characterization of JAZ-Interacting bHLH Transcription Factors That Regulate Jasmonate Responses in Arabidopsis. Journal of Experimental Botany, 62, 2143-2154. https://doi.org/10.1093/jxb/erq408
Weller, D.M., Mavrodi, D.V., Van Pelt, J.A., Pieterse, C.M.J., Van Loon, L.C. and Bakker, P.A.H.M. (2012) Induced Systemic Resistance (ISR) in Arabidopsis thaliana against Pseudomonas syringae pv. tomato by 2,4-Diacetylphloroglucinol-Producing Pseudomonas fluoresces. Phytopathology, 102, 403-412. https://doi.org/10.1094/PHYTO-08-11-0222
Zamioudis, C. and Pieterse, C.M.J. (2012) Modulation of Host Immunity by Beneficial Microbes. Molecular Plant-Microbe Interactions, 25, 139-150. https://doi.org/10.1094/MPMI-06-11-0179
Moffat, C.S., Ingle, R.A., Wathugala, D.L., Saunders, N.J., Knight, H. and Knight, M.R. (2012) ERF5 and ERF6 Play Redundant Roles as Positive Regulators of JA/Et-Mediated Defense against Botrytis cinerea in Arabidopsis. PLoS ONE, 7, e35995. https://doi.org/10.1371/journal.pone.0035995
Zander, M., La Camera, S., Lamotte, O., Metraux, J.P. and Gatz, C. (2010) Arabidopsis thaliana Class-II TGA Transcription Factors Are Essential Activators of Jasmonic Acid/Ethylene-Induced Defense Responses. The Plant Journal: For Cell and Molecular Biology, 61, 200-210. https://doi.org/10.1111/j.1365-313X.2009.04044.x
An, C. and Mou, Z. (2013) The Function of the Mediator Complex in Plant Immunity. Plant Signaling & Behavior, 8, e23182. https://doi.org/10.4161/psb.23182
Kidd, B.N., Edgar, C.I., Kumar, K.K., Aitken, E.A., Schenk, P.M., Manners, J.M. and Kazan, K. (2009) The Mediator Complex Subunit PFT1 Is a Key Regulator of Jasmonate-Dependent Defense in Arabidopsis. Plant Cell, 21, 2237-2252. https://doi.org/10.1105/tpc.109.066910
Berr, A., McCallum, E.J., Alioua, A., Heintz, D., Heitz, T. and Shen, W.H. (2010) Arabidopsis Histone Methyltransferase SET Domain Group 8 Mediates Induction of the Jasmonate/Ethylene Pathway Genes in Plant Defense Response to Necrotrophic Fungi. Plant Physiology, 154, 1403-1414. https://doi.org/10.1104/pp.110.161497
Shakeel, S.N., Wang, X., Binder, B.M. and Schaller, G.E. (2013) Mechanisms of Signal Transduction by Ethylene: Overlapping and Non-Overlapping Signaling Roles in a Receptor Family. AoB Plants, 5, plt010. https://doi.org/10.1093/aobpla/plt010
Denoux, C., Galletti, R., Mammarella, N., Gopalan, S., Werck, D., De Lorenzo, G., Ferrari, S., Ausubel, F.M. and Dewdney, J. (2008) Activation of Defense Response Pathways by OGs and Flg22 Elicitors in Arabidopsis Seedlings. Molecular Plant, 1, 423-445. https://doi.org/10.1093/mp/ssn019
Nambeesan, S., AbuQamar, S., Laluk, K., Mattoo, A.K., Mickelbart, M.V., Ferruzzi, M.G., Mengiste, T. and Handa, A.K. (2012) Polyamines Attenuate Ethylene-Mediated Defense Responses to Abrogate Resistance to Botrytis cinerea in Tomato. Plant Physiology, 158, 1034-1045. https://doi.org/10.1104/pp.111.188698
Vidhyasekaran, P. (2014) PAMP Signals in Plant Innate Immunity: Signal Perception and Transduction. Springer, Dordrecht, 442. https://doi.org/10.1007/978-94-007-7426-1
Zhu, L., Li, Y., Li, L., Yang, J. and Zhang, M. (2011) Ethylene Is Involved in Leafy Mustard Systemic Resistance to Turnip Mosaic Virus Infection through the Mitochondrial Alternative Oxidase Pathway. Physiological and Molecular Plant Pathology, 76, 166-172. https://doi.org/10.1016/j.pmpp.2011.09.005
Akagi, A., Dandekar, A.M. and Stotz, H.U. (2011) Resistance of Malus domestica Fruit to Botrytis cinerea Depends on Endogenous Ethylene Biosynthesis. Phytopathology, 101, 1311-1321. https://doi.org/10.1094/PHYTO-03-11-0087
Son, G.H., Wan, J., Kim, H.J., Nguyen, X.C., Chung, W.-S., Hong, J.C. and Stacey, G. (2012) Ethylene-Responsive Element-Binding Factor 5, ERF5, Is Involved in Chitin-Induced Innate Immunity Response. Molecular Plant-Microbe Interactions, 25, 48-60. https://doi.org/10.1094/MPMI-06-11-0165
Gaige, A.R., Ayella, A. and Shuai, B. (2010) Methyl Jasmonate and Ethylene Induce Partial Resistance in Medicago truncatula against the Charcoal Rot Pathogen Macrophomina phaseolina. Physiological and Molecular Plant Pathology, 74, 412-416. https://doi.org/10.1016/j.pmpp.2010.07.001
Boutrot, F., Segonzac, C., Chang, K.N., Qiao, H., Ecker, J.R., Zipfel, C. and Rathjen, J.P. (2010) Direct Transcriptional Control of the Arabidopsis Immune Receptor FLS2 by the Ethylene-Dependent Transcription Factors EIN3 and EIL1. Proceedings of the National Academy of Sciences of the USA, 107, 14502-14507. https://doi.org/10.1073/pnas.1003347107
Sharon, M., Freeman, S. and Sneh, B. (2011) Assessment of Resistance Pathways Induced in Arabidopsis thaliana by Hypovirulent Rhizoctonia spp. Isolates. Phytopathology, 101, 828-838. https://doi.org/10.1094/PHYTO-09-10-0247
Po-Wen, C., Singh, P. and Zimmerli, L. (2013) Priming of the Arabidopsis Pattern-Triggered Immunity Response upon Infection by Necrotrophic Pectobacterium carotovorum Bacteria. Molecular Plant Pathology, 14, 58-70. https://doi.org/10.1111/j.1364-3703.2012.00827.x
Zhu, Z., An, F., Feng, Y., Li, P., Xue, L.A.M., Jiang, Z., Kim, J.M., To, T.K., Li, W., Zhang, X., Yu, Q., Dong, Z., Chen, W.Q., Seki, M., Zhou, J.M. and Guo, H. (2011) Derepression of Ethylene-Stabilized Transcription Factors (EIN3/EIL1) Mediates Jasmonate and Ethylene Signaling Synergy in Arabidopsis. Proceedings of the National Academy of Sciences of the USA, 108, 12539-12544. https://doi.org/10.1073/pnas.1103959108
O’Donnell, P.J., Calvert, R., Atzorn, R., Wasternack, C., Leyser, H.M.O. and Bowles, D.J. (1996) Ethylene as a Signal Mediating the Wound Response of Tomato Plants. Science, 274, 1914-1917. https://doi.org/10.1126/science.274.5294.1914
Hudgins, J.W. and Franceschi, V.R. (2004) Methyl Jasmonate-Induced Ethylene Production Is Responsible for Conifer Phloem Defense Responses and Reprogramming of Stem Cambial Zone for Traumatic Resin Duct Formation. Plant Physiology, 135, 2134-2149. https://doi.org/10.1104/pp.103.037929
Ali, A., Pardo, J.M. and Yun, D.-J. (2020) Desensitization of ABA-Signaling: The Swing from Activation to Degradation. Frontiers in Plant Science, 11, 379. https://doi.org/10.3389/fpls.2020.00379
Schmidt, K., Pflugmacher, M., Klages, S., Maser, A., Mock, A. and Stahl, D.J. (2008) Accumulation of the Hormone Abscisic Acid (ABA) at the Infection Site of the Fungus Cercospora beticola Supports the Role of ABA as a Repressor of Plant Defense in Sugar Beet. Molecular Plant Pathology, 9, 661-673. https://doi.org/10.1111/j.1364-3703.2008.00491.x
Asselbergh, B., De vleesschauwer, D. and Hofte, M. (2008) Global Switches and Fine-Tuning ABA Modulates Plant Pathogen Defense. Molecular Plant-Microbe Interactions, 21, 709-719. https://doi.org/10.1094/MPMI-21-6-0709
Ton, J., Flors, V. and Mauch-Mani, B. (2009) The Multifaceted Role of ABA in Disease Resistance. Trends in Plant Sciences, 14, 310-317. https://doi.org/10.1016/j.tplants.2009.03.006
Alazem, M., Lin, K.Y. and Lin, N.S. (2014) The Abscisic Acid Pathway Has Multifaceted Effects on the Accumulation of Bamboo Mosaic Virus. Molecular Plant-Microbe Interactions, 27, 177-189. https://doi.org/10.1094/MPMI-08-13-0216-R
El Rahman, T.A., El Oirdi, M., Gonzalez-Lamothe, R. and Bouarab, K. (2012) Necrotrophic Pathogens Use Salicylic Acid Signaling Pathway to Promote Disease Development in Tomato. Molecular Plant-Microbe Interactions, 25, 1584-1593. https://doi.org/10.1094/MPMI-07-12-0187-R
Gimenez-Ibanez, S. and Solano, R. (2013) Nuclear Jasmonate and Salicylate Signaling and Crosstalk in Defense against Pathogens. Frontiers in Plant Science, 4, 72. https://doi.org/10.3389/fpls.2013.00072
Van der Does, D., Leon-Reyes, A., Koornneef, A., Van Verk, M.C., Rodenburg, N., Pauwels, L., Goossens, A., Korbes, A.P., Memelink, J., Ritsema, T., Van Wees, S.C.M. and Pieterse, C.M.J. (2013) Salicylic Acid Suppresses Jasmonic Acid Signaling Downstream of SCF COI1-JAZ by Targeting GCC Promoter Motifs via Transcription Factor ORA59. The Plant Cell, 25, 744-751. https://doi.org/10.1105/tpc.112.108548
Zander, M., Chen, S., Imkampe, J., Thurow, C. and Gatz, C. (2012) Repression of the Arabidopsis thaliana Jasmonic Acid/Ethylene-Induced Defense Pathway by TGA-Interacting Glutaredoxins Depends on Their C-Terminal ALWL Motif. Molecular Plant, 5, 831-840. https://doi.org/10.1093/mp/ssr113
Kachroo, A., Lapchyk, L., Fukushige, H., Hildebrand, D., Klessig, D. and Kachroo, P. (2003) Plastidial Fatty Acid Signaling Modulates Salicylic Acid- and Jasmonic Acid-Mediated Defense Pathways in the Arabidopsis ssi2 Mutant. The Plant Cell, 15, 2952-2965. https://doi.org/10.1105/tpc.017301
Leon-Reyes, A., Du, Y., Koornneef, A., Proietti, S., Korbes, A.P., Memelink, J., Pieterse, C.M.J. and Ritsema, T. (2010) Ethylene Signaling Renders the Jasmonate Response of Arabidopsis Insensitive to Future Suppression by Salicylic Acid. Molecular Plant-Microbe Interactions, 23, 187-197. https://doi.org/10.1094/MPMI-23-2-0187
Spoel, S.H., Koornneef, A., Claessens, S.M.C., Korzelius, J.P., Van Pelt, J.A., Mueller, M.J., Buchala, A.J., Metraux, J.-P., Brown, R., Kazan, K., Van Loon, L.C., Dong, X. and Pieterse, C.M.J. (2003) NPR1 Modulates Cross-Talk between Salicylate- and Jasmonate-Dependent Defense Pathways through a Novel Function in the Cytosol. The Plant Cell, 15, 760-770. https://doi.org/10.1105/tpc.009159
Spoel, S.H., Johnson, J.S. and Dong, X. (2007) Regulation of Tradeoffs between Plant Defenses against Pathogens with Different Lifestyles. Proceedings of the National Academy of Sciences of the USA, 104, 18842-18847. https://doi.org/10.1073/pnas.0708139104
Oliver, R.P. and Solomon, P.S. (2010) New Developments in Pathogenicity and Virulence of Necrotrophs. Current Opinion in Plant Biology, 13, 415-419. https://doi.org/10.1016/j.pbi.2010.05.003