Epigenetic control of plant immunity

Abstract

In eukaryotic genomes, gene expression and DNA recombination are affected by structural chromatin traits. Chromatin structure is shaped by the activity of enzymes that either introduce covalent modifications in DNA and histone proteins or use energy from ATP to disrupt histone-DNA interactions. The genomic 'marks' that are generated by covalent modifications of histones and DNA, or by the deposition of histone variants, are susceptible to being altered in response to stress. Recent evidence has suggested that proteins generating these epigenetic marks play crucial roles in the defence against pathogens. Histone deacetylases are involved in the activation of jasmonic acid- and ethylene-sensitive defence mechanisms. ATP-dependent chromatin remodellers mediate the constitutive repression of the salicylic acid-dependent pathway, whereas histone methylation at the WRKY70 gene promoter affects the activation of this pathway. Interestingly, bacterial-infected tissues show a net reduction in DNA methylation, which may affect the disease resistance genes responsible for the surveillance against pathogens. As some epigenetic marks can be erased or maintained and transmitted to offspring, epigenetic mechanisms may provide plasticity for the dynamic control of emerging pathogens without the generation of genomic lesions.

Descendants of Primed Arabidopsis Plants Exhibit Resistance to Biotic Stress

“…Although the molecular mechanisms of same-generation priming have recently started to be better understood (for review, see Conrath, 2011), the molecular details underlying transgenerational priming are still under study. However, recent groups have demonstrated that epigenetic mechanisms play a role in plant defense and several review articles comment on the possible involvement of epigenetic mechanisms in transgenerational phenomena (Chinnusamy and Zhu, 2009;Alvarez et al, 2010;Sano, 2010). Histone modifications are examples of epigenetic mechanisms; indeed, such modifications in the promoters of defense genes have been shown to correlate with transgenerational induced resistance in Arabidopsis against abiotic (Boyko et al, 2010) and biotic stresses (Luna et al, 2011).…”

Analysis of genetic stability of in vitro propagated potato microtubers using DNA markers

“…Hence a quality check up for true to type planting material at an early stage of development is considered to be very useful in plant tissue culture (Zilberman and Henikoff 2007). Although molecular basis of genetic variations are now becoming apparent that involves transcription, transposable element, chromosomal rearrangement, gene amplification, gene mutation (Alvarez et al 2010). Molecular markers serve as an important tool to check the genetic uniformity and true to type nature of micropropagated plants.…”

Next-Generation Systemic Acquired Resistance

“…Posttranslational modifications at the N-terminal tail of histone H3 can influence defense-related gene expression (van den Burg and Takken, 2009;Alvarez et al, 2010). Because these chromatin modifications can have long-lasting impacts on plant gene expression (Vaillant and Paszkowski, 2007), we investigated whether the altered responsiveness of PR-1 and PDF1.2 in P 1 plants is associated with changes in chromatin structure at the promoter regions of these genes.…”

“…The mechanisms of long-lasting maintenance of SAR, on the other hand, have remained less intensely studied. Recent studies have begun to analyze how epigenetic regulatory mechanisms, such as DNA methylation and chromatin remodeling, can have long-lasting impacts on gene expression and plant immunity (Bruce et al, 2007;van den Burg and Takken, 2009;Alvarez et al, 2010).…”