Integration of Ethylene and Jasmonic Acid Signaling Pathways in the Expression of Maize Defense Protein Mir1-CP

Ankala, Arunkanth; Luthe, Dawn S.; Williams, W. Paul; Wilkinson, J. R.

doi:10.1094/mpmi-22-12-1555

Cited by 50 publications

(48 citation statements)

References 68 publications

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“…Plants that were treated with buffer or water to dissolve MCP and ETP, respectively, were used as the controls. These results are different from those with caterpillar infestation, where both JA and ET are indispensable for mir1 transcript and Mir1-CP protein accumulation (Harfouche et al, 2006;Ankala et al, 2009). Taken together, no-choice bioassays in conjunction with qRT-PCR analysis of mir1 transcript expression indicate that CLA feeding-induced expression of mir1 is independent of JA but dependent on the ET pathway.…”

Section: Rmir1-cp Provides Direct Toxicity To Clacontrasting

confidence: 57%

“…Previous studies with fall armyworm indicated that JA functions upstream of ET in the Mir1-CP pathway, but both are required for Mir1-CP accumulation in response to caterpillar feeding (Harfouche et al, 2006;Ankala et al, 2009). To further determine the role of ET in contributing to mir1-mediated defense against CLA, Mp708 plants were pretreated with 1-methylcyclopropane (MCP; commercially available as Ethylbloc) and ethephon (ETP), which block and activate the ET pathway, respectively.…”

Section: Rmir1-cp Provides Direct Toxicity To Clamentioning

confidence: 99%

“…Furthermore, downstream genes that encode direct defense proteins such as proteinase inhibitor, chitinase, and Ribosome-Inactivating Protein2 are induced by caterpillar feeding (Shivaji et al, 2010;Chuang et al, 2014). Previous studies have shown that Mir1-CP accumulation in maize upon caterpillar feeding is dependent on both JA and ET pathways (Harfouche et al, 2006;Ankala et al, 2009).…”

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confidence: 99%

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Ethylene Contributes to maize insect resistance1-Mediated Maize Defense against the Phloem Sap-Sucking Corn Leaf Aphid

et al. 2015

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ORCID IDs: 0000-0001-7137-8797 (J.L.); 0000-0002-3904-6984 (S.B.); 0000-0003-3192-978X (S.V.); 0000-0002-3550-5522 (V.J.); 0000-0001-9147-3871 (W.P.W.).Signaling networks among multiple phytohormones fine-tune plant defense responses to insect herbivore attack. Previously, it was reported that the synergistic combination of ethylene (ET) and jasmonic acid (JA) was required for accumulation of the maize insect resistance1 (mir1) gene product, a cysteine (Cys) proteinase that is a key defensive protein against chewing insect pests in maize (Zea mays). However, this study suggests that mir1-mediated resistance to corn leaf aphid (CLA; Rhopalosiphum maidis), a phloem sap-sucking insect pest, is independent of JA but regulated by the ET-signaling pathway. Feeding by CLA triggers the rapid accumulation of mir1 transcripts in the resistant maize genotype, Mp708. Furthermore, Mp708 provided elevated levels of antibiosis (limits aphid population)-and antixenosis (deters aphid settling)-mediated resistance to CLA compared with B73 and Tx601 maize susceptible inbred lines. Synthetic diet aphid feeding trial bioassays with recombinant Mir1-Cys Protease demonstrates that Mir1-Cys Protease provides direct toxicity to CLA. Furthermore, foliar feeding by CLA rapidly sends defensive signal(s) to the roots that trigger belowground accumulation of the mir1, signifying a potential role of long-distance signaling in maize defense against the phloem-feeding insects. Collectively, our data indicate that ET-regulated mir1 transcript accumulation, uncoupled from JA, contributed to heightened resistance to CLA in maize. In addition, our results underscore the significance of ET acting as a central node in regulating mir1 expression to different feeding guilds of insect herbivores.

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Section: Rmir1-cp Provides Direct Toxicity To Clacontrasting

confidence: 57%

Section: Rmir1-cp Provides Direct Toxicity To Clamentioning

confidence: 99%

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confidence: 99%

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Ethylene Contributes to maize insect resistance1-Mediated Maize Defense against the Phloem Sap-Sucking Corn Leaf Aphid

et al. 2015

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“…This selection included the entire gene families of maize LOX (see Supplemental Table 1 online), OPR (Zhang et al, 2005), and JAZ genes (maize JAZs, see Supplemental Table 1 online; Arabidopsis JAZs, Yan et al, 2007). We also selected other defense genes of interest, including MPI (Tamayo et al, 2000), the ethylene biosynthesis genes ACS2, ACS6, and ACS7 (Young et al, 2004), the insect defense gene Mir1 (Ankala et al, 2009), the defensin gene PDC (Kant et al, 2009), and the anthocyanin biosynthesis genes A1, A2, C2, BZ1, and BZ2 (see Supplemental Table 1 online). The macroarray profile revealed that 67 of this 85-gene set, including LOX7/8, LOX9, AOS1, OPR7/8, MYC2, JAZ7, JAZ8, and MYC2, etc., were upregulated 1 and 2 h Table 1 online) in response to wounding of opr7-5 opr8-2 and wild-type plants.…”

Section: Opr7 Opr8 Mutants Are Compromised In Resistance To a Chewingmentioning

confidence: 99%

“…Although JA-regulated defense pathways have been extensively studied in the model plant Arabidopsis and other dicots (Howe and Jander, 2008), far less is known about their role in regulating direct herbivore defenses in monocots, especially in an economically significant crop like maize (Ankala et al, 2009). The creation of JA-deficient opr7 opr8 mutants provided an excellent tool to test whether JA has a similar insect defense signaling role in maize.…”

Section: Ja Is An Indispensable Signal In Maize For Defense Response mentioning

confidence: 99%

Disruption of OPR7 and OPR8 Reveals the Versatile Functions of Jasmonic Acid in Maize Development and Defense

et al. 2012

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Here, multiple functions of jasmonic acid (JA) in maize (Zea mays) are revealed by comprehensive analyses of JA-deficient mutants of the two oxo-phytodienoate reductase genes, OPR7 and OPR8. Single mutants produce wild-type levels of JA in most tissues, but the double mutant opr7 opr8 has dramatically reduced JA in all organs tested. opr7 opr8 displayed strong developmental defects, including formation of a feminized tassel, initiation of female reproductive buds at each node, and extreme elongation of ear shanks; these defects were rescued by exogenous JA. These data provide evidence that JA is required for male sex determination and suppression of female reproductive organ biogenesis. Moreover, opr7 opr8 exhibited delayed leaf senescence accompanied by reduced ethylene and abscisic acid levels and lack of anthocyanin pigmentation of brace roots. Remarkably, opr7 opr8 is nonviable in nonsterile soil and under field conditions due to extreme susceptibility to a root-rotting oomycete (Pythium spp), demonstrating that these genes are necessary for maize survival in nature. Supporting the importance of JA in insect defense, opr7 opr8 is susceptible to beet armyworm. Overall, this study provides strong genetic evidence for the global roles of JA in maize development and immunity to pathogens and insects.

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Fungal endophytes enhanced insect resistance by improving the defenses of Achnatherum sibiricum before locust feeding

Qin,

Shi,

Yin

et al. 2024

Pest Management Science

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BACKGROUNDEpichloë endophytes provide many benefits to host plants, including enhanced insect resistance. Fungal alkaloids are usually thought to be responsible for the endophyte‐conferred herbivore resistance. Nonetheless, the fungal alkaloid profiles and concentrations may vary considerably among grass–endophyte systems. This indicates that apart from fungal alkaloids, additional mechanisms such as endophyte‐mediated host defense are likely contributed to endophyte–grass–insect interactions. In this study, we addressed this issue by investigating the effect of Epichloë on the defense responses of Achnatherum sibiricum against locusts.RESULTSThe results showed that Epichloë endophytes increased locust resistance of A. sibiricum in both choice and non‐choice feeding experiments. In no feeding groups, endophyte infection increased the content of jasmonic acid (JA) and ethylene (ET), chitinase activity, and the biosynthetic gene expression of the relevant pathways. Endophyte infection also increased the content of total phenolics and condensed tannins. These indicators were negatively correlated with leaf consumption. In locust feeding groups, endophyte infection increased trypsin inhibitor activity. Exogenous application of phytohormones further proved that JA and ET reduced the consumption of A. sibiricum by locusts.CONCLUSIONThe present study showed that endophyte‐conferred host defense was mainly constitutive, that is, the defense characteristics of host plants were mainly manifested in no feeding groups. Endophyte presence enhanced locust resistance of the host by activating the JA/ET signaling pathway, elevating chitinase activity and phenolic compounds content, thereby improving the defense ability of host plants. © 2024 Society of Chemical Industry.

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Integration of Ethylene and Jasmonic Acid Signaling Pathways in the Expression of Maize Defense Protein Mir1-CP

Cited by 50 publications

References 68 publications

Ethylene Contributes to maize insect resistance1-Mediated Maize Defense against the Phloem Sap-Sucking Corn Leaf Aphid

Ethylene Contributes to maize insect resistance1-Mediated Maize Defense against the Phloem Sap-Sucking Corn Leaf Aphid

Disruption of OPR7 and OPR8 Reveals the Versatile Functions of Jasmonic Acid in Maize Development and Defense

Fungal endophytes enhanced insect resistance by improving the defenses of Achnatherum sibiricum before locust feeding

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