Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2019 Jun 21:10:752.
doi: 10.3389/fpls.2019.00752. eCollection 2019.

The OsMPK15 Negatively Regulates Magnaporthe oryza and Xoo Disease Resistance via SA and JA Signaling Pathway in Rice

Yongbo Hong  1   2 , Qunen Liu  1   2 , Yongrun Cao  1   2 , Yue Zhang  1   2 , Daibo Chen  1   2 , Xiangyang Lou  1   2 , Shihua Cheng  1   2 , Liyong Cao  1   2
Affiliations

The OsMPK15 Negatively Regulates Magnaporthe oryza and Xoo Disease Resistance via SA and JA Signaling Pathway in Rice

Yongbo Hong et al. Front Plant Sci. .

Abstract

Mitogen-activated protein kinase (MAPK) cascades play central roles in response to biotic and abiotic stresses. However, the mechanisms by which various MAPK members regulate the plant immune response in rice remain elusive. In this article, to characterize the mechanisms, the knock-out and overexpression mutants of OsMPK15 were constructed and the disease resistance was investigated under the various fungal and bacterial inoculations. The knock-out mutant of OsMPK15 resulted in the constitutive expression of pathogenesis-related (PR) genes, increased accumulation of reactive oxygen species (ROS) triggered by the pathogen-associated molecular pattern (PAMP) elicitor chitin, and significantly enhanced the disease resistance to different races of Magnaporthe oryzae and Xanthomonas oryzae pv. oryzae (Xoo), which cause the rice blast and bacterial blight diseases, respectively. On contrary, the expression of PR genes and ROS were down-regulated in the OsMPK15-overexpressing (OsMPK15-OE) lines. Meanwhile, phytohormones such as salicylic acid (SA) and jasmonic acid (JA) were accumulated in the mpk15 mutant lines but decreased in the OsMPK15-OE lines. The expression of SA- and JA-pathway associated genes were significantly upregulated in the mpk15 mutant, whereas it was down regulated in the OsMPK15-OE lines. We conclude that OsMPK15 may negatively regulate the disease resistance through modulating SA- and JA-mediated signaling pathway.

Keywords: M. oryzae; OsMPK15; PRs; ROS; SA/JA; Xoo; rice.

PubMed Disclaimer

Figures

FIGURE 1
FIGURE 1
Generation of Crispr/Cas9 edited mpk15 mutant and OsMPK15-OE lines. (A) Sequence confirmation of the homogenous mpk15-1 and mpk15-2 mutant lines., (B) Schematic diagram of the overexpression construct for rice transformation. HPT II, Hygromycin phosphotransferase II; LB, left border; RB, right border; Ubi, maize ubiquitin promoter; 35S, CaMV 35S promoter. (C) OsMPK15 expression levels in the WT, mpk15 mutant, and OsMPK15-OE lines at 30-days-old seedling. Data presented are the means ± SD from three independent experiments. ∗P ≤ 0.05; ∗∗P ≤ 0.01 (Student’s t-test).
FIGURE 2
FIGURE 2
Phenotypic comparison of the WT, mpk15 mutant, and OsMPK15-OE lines. (A) The phenotype of the WT, mpk15 mutant, and OsMPK15-OE lines at 102 days post-sowing (dps). Bars indicate a length of 15 cm. (B) Magnified view of the flag leaf, top second, and top third leaves in the WT, mpk15 mutant, and OsMPK15-OE line at 102 dps. Among them, the top third of OsMPK15-OE has obvious bacterial blight lesion. (C,D) panicle phenotype and length in the WT, mpk15 mutant, and OsMPK15-OE lines. Bars indicate 5 cm. Data presented are the mean ± SD from three independent experiments. ∗P ≤ 0.05; ∗∗P ≤ 0.01 (Student’s t-test).
FIGURE 3
FIGURE 3
OsMPK15 negatively regulates M. oryzae disease resistance in detached leaves. (A,B) Phenotype of the at 30-days-old WT, mpk15 mutant, and OsMPK15-OE plants inoculated by the punch method with spore suspension (1 × 105 per ml) of M. oryzae strain 46-2 or race RB22 at 6 dpi. Bars indicate 1 cm. (C) DAB staining in M. oryzae strain RB22 inoculated leaves of WT, mpk15 mutant, and OsMPK15-OE plants at 6 dpi. Bars indicate 1 cm. (D) Disease lesion size statistics of M. oryzae strain 46-2 inoculated WT, mpk15 mutant, and OsMPK15-OE plants. At least 30 plants in each experiment were evaluated for lesion size with three replicates. (E) Quantification of M. oryzae growth in strain 46-2 and RB22-inoculated leaves of the WT, mpk15 mutant, and OsMPK15-OE plants at 6 dpi. Amounts of M. oryzae 28S rDNA and rice OsEF1 genomic DNA were estimated by qRT-PCR and relative fungal growth were shown as ratios of Mo28S/OsEF1. Three independent experiments were performed with similar results in (A–E) Data presented in (D,E) are the mean ± SD from three independent experiments. ∗P ≤ 0.05; ∗∗P ≤ 0.01 (Student’s t-test).
FIGURE 4
FIGURE 4
OsMPK15 negatively regulates the bacterial disease resistance to X. oryzae pv. oryzae. The WT, mpk15 mutant, and OsMPK15-OE plants were inoculated with Xoo strains PXO96 and Zhe817 using the leaf clipping method at the 90-days-old (booting stage). (A,B) Disease symptom on the PXO96 and Zhe817-inoculated leaves at 15 dpi. Rulers were indicated on the left. (C,D) Lesion length on the inoculated leaves at 15 dpi. At least 12 plants in each experiment were used for measurement of the lesion length. Data presented in (C,D) are the mean ± SD from three independent experiments. ∗P ≤ 0.05; ∗∗P ≤ 0.01 (Student’s t-test).
FIGURE 5
FIGURE 5
Increase in the ROS accumulation and disease-related hormone levels in the mpk15 mutants. (A) ROS accumulation dynamics in the WT, mpk15 mutant, and OsMPK15-OE plants at 90 dps after treatment of chitin and water (mock) treatment served as a control. Error bars are computed from three replicates (n = 3). (B,C) The 30-day-old seedling leaf samples of the WT, mpk15 mutant and OsMPK15-OE lines under normal conditions were used for analyses of SA and JA contents. FW: fresh weight. Data presented are the mean ± SD from three independent experiments. ∗P ≤ 0.05; ∗∗P ≤ 0.01 (Student’s t-test).
FIGURE 6
FIGURE 6
Expression pattern of defense signaling genes in the WT, mpk15 mutant, and OsMPK15-OE lines. The 30-day-old seedlings samples of different lines under normal conditions were used for qRT-PCR analyses. (A) The expression pattern of pathogenesis-related (PR) genes includes PR4, PR5, PR8, PR10, and PAL. (B) Expression pattern of the MPK3, MPK6, SA-mediated signaling marker gene WRKY45, and JA biosynthesis genes include LOX, OPR1, AOS1, AOS2, and AOS4. Data presented are the mean ± SD from three independent experiments. ∗P ≤ 0.05; ∗∗P ≤ 0.01 (Student’s t-test).
FIGURE 7
FIGURE 7
Agronomic phenotypes of the WT, mpk15 mutant, and OsMPK15-OE lines. (A,B) Comparison of plant height and tiller numbers among the WT, mpk15 mutant, and OsMPK15-OE plants (n = 10). (C–F) Comparison of grain number per panicle, seed setting rate, 1,000-grain weight, and yield per plant among the WT, mpk15 mutant, and OsMPK15-OE lines (n = 10). Data presented are the mean ± SD from 2 years of independent experiments with a similar result. ∗P ≤ 0.05; ∗∗P ≤ 0.01 (Student’s t-test).
FIGURE 8
FIGURE 8
Grain length and width of the WT, mpk15 mutant, and OsMPK15-OE lines. (A,B) The phenotype of grain length and width from the WT, mpk15 mutant, and OsMPK15-OE lines. Bars indicate 10 mm. (C,D) Statistics of grain length and width (n = 300), respectively. ∗P ≤ 0.05; ∗∗P ≤ 0.01 (Student’s t-test).
See this image and copyright information in PMC

Similar articles

See all similar articles

Cited by

See all "Cited by" articles

References

    1. Asai T., Tena G., Plotnikova J., Willmann M. R., Chiu W. L., Gomez-Gomez L., et al. (2002). MAP kinase signaling cascade in Arabidopsis innate immunity. Nature 415 977–983. - PubMed
    1. Bent A. F. (2001). Plant mitogen-activated protein kinase cascades: negative regulatory roles turn out positive. Proc. Natl. Acad. Sci. U.S.A. 98 784–786. 10.1073/pnas.98.3.784 - DOI - PMC - PubMed
    1. Bertini L., Proietti S., Focaracci F., Benedetta S., Caruso C. (2018). Epigenetic control of defense genes following MeJA-induced priming in rice (O. sativa). J. Plant Physiol. 228 166–177. 10.1016/j.jplph.2018.06.007 - DOI - PubMed
    1. Brown J. K. (2002). Yield penalties of disease resistance in crops. Curr. Opin. Plant Biol. 5 339–344. - PubMed
    1. Century K. S., Shapiro A. D., Repetti P. P., Dahlbeck D., Holub E., Staskawicz B. J. (1997). NDR1, a pathogen-induced component required for Arabidopsis disease resistance. Science 278 1963–1965. - PubMed