Browsing by Author "Oh, Sunhee"

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General Control Non-repressible-4 (GCN4) degrades 14-3-3 and the RIN4 complex to regulate stomatal aperture with implications on nonhost disease resistance and drought tolerance
(American Society of Plant Biologists, 2017) Kaundal, Amita; Ramu, Vemanna S; Oh, Sunhee; Lee, Seonghee; Pant, Bikram; Lee, Hee-Kyung; Rojas, Clemencia M.; Senthil-Kumar, Muthappa; Mysore, Kirankumar S.
Plants have complex and adaptive innate immune responses against pathogen infections. Stomata are key entry points for many plant pathogens. Both pathogens and plants regulate stomatal aperture for pathogen entry and defense, respectively. Not all plant proteins involved in stomatal aperture regulation have been identified. Here we report general control non-repressible-4 (GCN4), an AAA+-ATPase family protein, as one of the key proteins regulating stomatal aperture during biotic and abiotic stress. Silencing of GCN4 in Nicotiana benthamiana and Arabidopsis compromises host and nonhost disease resistance due to open stomata during pathogen infection. AtGCN4 overexpression plants have reduced H+-ATPase activity, less responsive stomata to coronatine or fusicoccin, have reduced pathogen entry, and confers drought tolerance. This study also demonstrates that AtGCN4 interacts with RIN4 and 14-3-3 proteins and suggest that GCN4 may degrade RIN4 and 14-3-3 proteins via a proteasome mediated pathway to reduce the activity of plasma membrane H+-ATPase complex thus reducing proton pump activity to close stomata.
A novel role of salt and drought induced RING 1 protein in modulating plant defense against hemibiotrophic and necrotrophic pathogens
(American Phytopathological Society, 2021) Ramu, Vemanna S.; Oh, Sunhee; Lee, Hee-Kyung; Nandety, Raja Sekhar; Oh, Youngjae; Lee, Seonghee; Nakashima, Jin; Tang, Yuhong; Senthil-Kumar, Muthappa; Mysore, Kirankumar S.
Many plant encoded E3 ligases are known to be involved in plant defense. Here we report a novel role of E3 ligase SALT- AND DROUGHT-INDUCED RING FINGER1 (SDIR1) in plant immunity. Even though SDIR1 is reasonably well-characterized, its role in biotic stress response is not known. The silencing of SDIR1 in Nicotiana benthamiana reduced the multiplication of the virulent bacterial pathogen Pseudomonas syringae pv. tabaci. The Arabidopsis sdir1 mutant is resistant to virulent pathogens, whereas SDIR1 overexpression lines are susceptible to both host and nonhost hemibiotrophic bacterial pathogens. However, sdir1 mutant and SDIR1 overexpression lines showed hypersusceptibility and resistance, respectively, against the necrotrophic pathogen, Erwinia carotovora. The mutant of SDIR1 target protein, SDIR-interacting protein 1 (SDIR1P1), also showed resistance to host and nonhost pathogens. In SDIR1 overexpression plants, transcripts of NAC transcription factors were less accumulated and the levels of JA and abscisic acid (ABA) were increased. In sdir1 mutants, JA signaling genes JAZ7 and JAZ8 were downregulated. These data suggest that SDIR1 is a susceptibility factor, and its activation/overexpression enhances disease caused by P. syringae pv. tomato DC3000 in Arabidopsis. Our results show a novel role of SDIR1 in modulating plant defense gene expression and plant immunity.
Ribosomal protein QM/RPL10 positively regulates defence and protein translation mechanisms during nonhost disease resistance
(John Wiley & Sons, 2020) Ramu, Vemanna S.; Dawane, Akashata; Lee, Seonghee; Oh, Sunhee; Lee, Hee-Kyung; Sun, Liang; Senthil-Kumar, Muthappa; Mysore, Kirankumar S.
Ribosomes play an integral part in plant growth, development, and defence responses. We report here the role of ribosomal protein large (RPL) subunit QM/RPL10 in nonhost disease resistance. The RPL10-silenced Nicotiana benthamiana plants showed compromised disease resistance against nonhost pathogen Pseudomonas syringae pv. tomato T1. The RNA-sequencing analysis revealed that many genes involved in defence and protein translation mechanisms were differentially affected due to silencing of NbRPL10. Arabidopsis AtRPL10 RNAi and rpl10 mutant lines showed compromised nonhost disease resistance to P. syringae pv. tomato T1 and P. syringae pv. tabaci. Overexpression of AtRPL10A in Arabidopsis resulted in reduced susceptibility against host pathogen P. syringae pv. tomato DC3000. RPL10 interacts with the RNA recognition motif protein and ribosomal proteins RPL30, RPL23, and RPS30 in the yeast two-hybrid assay. Silencing or mutants of genes encoding these RPL10- interacting proteins in N. benthamiana or Arabidopsis, respectively, also showed compromised disease resistance to nonhost pathogens. These results suggest that QM/ RPL10 positively regulates the defence and translation-associated genes during nonhost pathogen infection.
The small GTPase, nucleolar GTP-binding protein 1 (NOG1), has a novel role in plant innate immunity
(Nature Publishing Group, 2017) Lee, Seonghee; Senthil-Kumar, Muthappa; Kang, Miyoung; Rojas, Clemencia M.; Tang, Yuhong; Oh, Sunhee; Choudhury, Swarup Roy; Lee, Hee-Kyung; Ishiga, Yasuhiro; Allen, Randy D.; Pandey, Sona; Mysore, Kirankumar S.
Plant defense responses at stomata and apoplast are the most important early events during plant-bacteria interactions. The key components for the signaling of stomatal defense and nonhost resistance have not been fully characterized. Here we report the newly identified small GTPase, Nucleolar GTP-binding protein 1 (NOG1), functions for plant immunity against bacterial pathogens. Virus-induced gene silencing of NOG1 compromised nonhost resistance in N. benthamiana and tomato. Comparative genomic analysis showed that two NOG1 copies are present in all known plant species: NOG1-1 and NOG1-2. Gene downregulation and overexpression studies of NOG1-1 and NOG1-2 in Arabidopsis revealed the novel function of these genes in nonhost resistance and stomatal defense against bacterial pathogens, respectively. Specially, NOG1-2 regulates guard cell signaling in response to biotic and abiotic stimuli through jasmonic acid (JA)- and abscisic acid (ABA)-mediated pathways. The results here provide valuable information on the new functional role of small GTPase, NOG1, in guard cell signaling and early plant defense in response to bacterial pathogens.