Next-Generation Systemic Acquired Resistance
Next-Generation Systemic Acquired Resistance
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DOI：
10.1104/pp.111.187468
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发表时间：
2012-02-01
期刊：
影响因子：
7.4
通讯作者：
Ton, Jurriaan
中科院分区：
文献类型：
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作者：
Luna, Estrella;Bruce, Toby J. A.;Ton, Jurriaan
系统获得性抗性（systemicacquiredresistance，SAR）是植物对病原菌攻击的一种免疫反应。最近的证据表明，植物免疫涉及染色质重塑和DNA甲基化的调节。我们研究了SAR是否可以在番茄假单胞菌致病变种DC 3000（PstDC 3000）的病害压力下表观遗传地遗传。与来自对照处理的拟南芥（拟南芥; C-1）的后代相比，来自PstDC 3000接种的拟南芥（P-1）的后代被引发以激活水杨酸（SA）诱导的防御基因，并且对（半）活体营养型病原体阿拉伯透明操纵孢菌和PstDC 3000更具抗性。这种跨代SAR持续超过一个无压力的一代，表明表观遗传的基础上的现象。此外，P-1后代表现出茉莉酸（JA）诱导基因的反应性降低，提高了对坏死营养型真菌芸苔链格孢的敏感性。SA和JA依赖性基因反应的这种转变与相应激素水平的变化无关。相反，染色质免疫沉淀分析显示，在P-1植物中，SA诱导的致病相关基因1、WRKY 6和WRKY 53的启动子在赖氨酸9处富含乙酰化组蛋白H3，这是一种与转录允许状态相关的染色质标记。相反，植物防御素1.2的JA诱导型启动子显示赖氨酸27处的H3三重甲基化增加，这是与抑制的基因转录相关的标记。来自PR 1（npr 1）-1的防御调节突变体非表达子的P-1后代未能形成跨代防御表型，表明NPR 1在跨代SAR表达中起关键作用。此外，在非CpG DNA甲基化中受影响的drm 1drm 2cmt 3突变体模拟了跨代SAR表型。由于PstDC 3000诱导拟南芥DNA低甲基化，我们的研究结果表明，跨代SAR是由低甲基化基因，直接引发SA依赖的防御在下一代。
Systemic acquired resistance (SAR) is a plant immune response to pathogen attack. Recent evidence suggests that plant immunity involves regulation by chromatin remodeling and DNA methylation. We investigated whether SAR can be inherited epigenetically following disease pressure by Pseudomonas syringae pv tomato DC3000 (PstDC3000). Compared to progeny from control-treated Arabidopsis (Arabidopsis thaliana; C-1), progeny from PstDC3000-inoculated Arabidopsis (P-1) were primed to activate salicylic acid (SA)-inducible defense genes and were more resistant to the (hemi) biotrophic pathogens Hyaloperonospora arabidopsidis and PstDC3000. This transgenerational SAR was sustained over one stress-free generation, indicating an epigenetic basis of the phenomenon. Furthermore, P-1 progeny displayed reduced responsiveness of jasmonic acid (JA)-inducible genes and enhanced susceptibility to the necrotrophic fungus Alternaria brassicicola. This shift in SA- and JA-dependent gene responsiveness was not associated with changes in corresponding hormone levels. Instead, chromatin immunoprecipitation analyses revealed that SA-inducible promoters of PATHOGENESIS-RELATED GENE1, WRKY6, and WRKY53 in P-1 plants are enriched with acetylated histone H3 at lysine 9, a chromatin mark associated with a permissive state of transcription. Conversely, the JA-inducible promoter of PLANT DEFENSIN1.2 showed increased H3 triple methylation at lysine 27, a mark related to repressed gene transcription. P-1 progeny from the defense regulatory mutant non expressor of PR1 (npr1)-1 failed to develop transgenerational defense phenotypes, demonstrating a critical role for NPR1 in expression of transgenerational SAR. Furthermore, the drm1drm2cmt3 mutant that is affected in non-CpG DNA methylation mimicked the transgenerational SAR phenotype. Since PstDC3000 induces DNA hypomethylation in Arabidopsis, our results suggest that transgenerational SAR is transmitted by hypomethylated genes that direct priming of SA-dependent defenses in the following generations.