Plants are sessile organisms that cannot physically relocate to escape from unfavorable environmental conditions and have developed complex defense mechanisms to respond to biotic and abiotic stresses. The molecular mechanisms of stress-induced signaling pathways and genes differ between various stresses such as pathogen attack, cold, heat, drought, and salinity [1, 2]. However, there is supporting evidence for cross talk between signaling pathways that respond to biotic and abiotic stresses [3]. Pathogen stress is one of the most complex and devastating stresses that is witnessed in plants [4]. Pattern-triggered immunity (PTI) is activated in plants as an early defense response [5] and the role of defense-rela... More
Plants are sessile organisms that cannot physically relocate to escape from unfavorable environmental conditions and have developed complex defense mechanisms to respond to biotic and abiotic stresses. The molecular mechanisms of stress-induced signaling pathways and genes differ between various stresses such as pathogen attack, cold, heat, drought, and salinity [1, 2]. However, there is supporting evidence for cross talk between signaling pathways that respond to biotic and abiotic stresses [3]. Pathogen stress is one of the most complex and devastating stresses that is witnessed in plants [4]. Pattern-triggered immunity (PTI) is activated in plants as an early defense response [5] and the role of defense-related genes including cell wall modifying genes has been reported [6].
In agriculturally important crops such as common bean, significant yield losses due to biotic (62%) and abiotic (37-67%) stresses have been reported [7]. Bean-rust, a disease caused by the fungal pathogen Uromyces appendiculatus is a major concern for common bean production worldwide [8]. Tropical and subtropical areas in the world have been mostly affected by epidemics of this disease. The diversity in virulence of U . appendiculatus in many geographic regions has been reported [9-11]. The high genetic variability of the rust fungus is an important problem that continues to complicate the development of durable resistant varieties in common bean. Integrated molecular genetic and genomic analyses of defense responsive pathways and genes will aid in unraveling the underlying disease-resistance mechanisms, which in turn will aid in developing broader and more robust resistance in common bean cultivars while providing a more comprehensive understanding of plant disease resistance in general.
Epigenetic and epigenomic regulation including histone and chromatin modifications can modulate stress responses by activating or repressing transcription by coordinating "open" or "closed" chromatin conformations, respectively [12]. In some cases, chromatin changes are steady and autonomous as a result of heritable epialleles that induce phenotypic alteration [13]. Epigenetic modifications can be induced by sustained exposure to pathogens that result in a stable epigenetic characteristic of resistance or tolerance [14]. Changes in histone modification marks have been shown to influence gene regulatory mechanisms in Arabidopsis thaliana [15]. Diversity in gene expression at both the tissue-specific and population levels has been reflected by the alteration of DNA methylation [4]. Determining the role of transcriptional networks is not only helpful in understanding the molecular mechanisms of plant responses to biotic and abiotic stress tolerance, but it is also useful for improving stress tolerance by genetic engineering. Previous studies showed that histone modifications are involved in abiotic [16, 17] and biotic responses [18, 19]. In transgenic Arabidopsis , over-expression of the histone deacetylase, AtHD2C resulted in abscisic acid (ABA) insensitivity and showed tolerance to salt and drought stresses [20]. The histone acetyltransferase1-dependent epigenetic mark involved in pattern triggered immunity (PTI) against Pseudomonas syringae has been reported in Arabidopsis...
