Abstract
BackgroundJumonji C (JmjC) domain-containing proteins are a group of functionally conserved histone lysine demethylases in Eukaryotes. Growing evidences have shown that JmjCs epigenetically regulate various biological processes in plants. However, their roles in plant biotic stress, especially in rice bacterial blight resistance have been barely studied so far.ResultsIn this study, we found that the global di- and tri-methylation levels on multiple lysine sites of histone three were dramatically altered after being infected by bacterial blight pathogen Xanthomonas oryzae pv. oryzae (Xoo). Xoo infection induced the transcription of 15 JmjCs, suggesting these JmjCs are involved in rice bacterial blight defense. Further functional characterization of JmjC mutants revealed that JMJ704 is a positive regulator of rice bacterial blight resistance as the jmj704 became more susceptible to Xoo than the wild-type. In jmj704, the H3K4me2/3 levels were significantly increased; suggesting JMJ704 may be involved in H3K4me2/3 demethylation. Moreover, JMJ704 suppressed the transcription of the rice defense negative regulator genes, such as NRR, OsWRKY62 and Os-11N3, by reducing the activation marks H3K4me2/3 on them.ConclusionsJMJ704 may be a universal switch controlling multiple genes of the bacterial blight resistance pathway. JMJ704 positively regulates rice defense by epigenetically suppressing master negative defense regulators, presenting a novel mechanism distinct from its homolog JMJ705 which also positively regulates rice defense but via activating positive defense regulators.Electronic supplementary materialThe online version of this article (doi:10.1186/s12870-015-0674-3) contains supplementary material, which is available to authorized users.
Highlights
Jumonji C (JmjC) domain-containing proteins are a group of functionally conserved histone lysine demethylases in Eukaryotes
JMJ701-JMJ720 are classified into five different groups on the basis of the JmjC domain and the overall protein domain architecture, including JmjC domain-containing histone demethylase 2 (JHDM2), JmjC domain-containing 2 (JMJD2), JmjC protein containing AT-rich interaction domain (JARID), JmjC domain only and N-terminal FY-rich_C-terminal FY-rich ( FYRN_FYRC) [18]
The nuclear-rich proteins were isolated from the leaves of four-week-old Nipponbare plants inoculated with Xanthomonas oryzae pv. oryzae (Xoo) at 0, 4, 8, 12, 24, and 72 h, and Western blot analysis was performed using antibodies against di- and tri-methylated H3K4, H3K9, H3K27, and H3K36 respectively
Summary
Jumonji C (JmjC) domain-containing proteins are a group of functionally conserved histone lysine demethylases in Eukaryotes. Growing evidences have shown that JmjCs epigenetically regulate various biological processes in plants. Their roles in plant biotic stress, especially in rice bacterial blight resistance have been barely studied so far. Mono-, di- or tri-methylation for histone H3 at lysine 4, 9, 27, 36(H3K4me1/me2/ me3,H3K9me1/me2/me3,H3K27me1/me2/me3,H3K36me 1/me2/me3) has been implicated in epigenetic gene regulation [4]. KDMs contain two known evolutionarily conserved types: lysine specific demethylase (LSD1) [7] and histone demethylases featured with the jumonji C (JmjC) domain [8, 9]. The JmjC domain-containing histone demethylases are generally conserved in yeast, animal and plant [8, 13]. JMJ701-JMJ720 are classified into five different groups on the basis of the JmjC domain and the overall protein domain architecture, including JmjC domain-containing histone demethylase 2 (JHDM2), JmjC domain-containing 2 (JMJD2), JmjC protein containing AT-rich interaction domain (JARID), JmjC domain only and N-terminal FY-rich_C-terminal FY-rich ( FYRN_FYRC) [18]
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