Genes associated with hypersensitive response (HR) in the citrus EST database (CitEST)

Abstract

Plants are continuously exposed to pathogen attack, but successful infection is rare because they protect themselves against pathogens using a wide range of response mechanisms. One of them is the hypersensitive response (HR), which is a form of cell death often associated with plant resistance to pathogen infection to prevent the spreadsebpg@cnpq.brsebpg@cnpq.br of the potential pathogen from infected to uninfected tissues. Cell death is activated by recognition of pathogen-derived molecules by the resistance (R) gene products, and is associated with the massive accumulation of reactive oxygen species (ROS), salicylic acid (SA), and other pro-death signals such as nitric oxide (NO). The analysis of the citrus EST (CitEST) database revealed the presence of putative genes likely to be involved in HR through their products, like metacaspases, lipoxygenases, phospholipases, pathogenesis-related proteins, glutathione transferases/peroxidases, enzymes involved in the phenylpropanoid pathway and in the formation and detoxification of ROS, as well as those involved in the formation and regulation of ion channels, SA and NO. By analysis of the EST database of Citrus, it was possible to identify several putative genes that code for key enzymes involved in HR triggering and also in plant defense against biotic and abiotic stress.Key words: otic and abiotic stress response, plant-pathogen incompatible interaction, programmed cell death, plant disease resistance.

Systematic analysis of O -methyltransferase gene family and identification of potential members involved in the formation of O -methylated flavonoids in Citrus

“…Plant OMTs play important roles in the structural diversity of natural compounds. Enzymatic O-methylation of specific natural compounds changes their biological roles by altering their reactivity and solubility and their ability to interact with other chemical structures (Gana et al, 2013;Guidetti-Gonzalez et al, 2007).…”

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“…Tyrosine aminotransferase ( Figure 3D) is involved in tocopherol synthesis (Munné-Bosch 2005) and other benzylisoquinoline alkaloids (Lee & Facchini 2011) which are natural antioxidants. Chitinase activity ( Figure 3C), the presence of a putative anion transporter, and calcium influx, are signatures that an early oxidative burst event associated with the HR was ongoing, as has also been suggested in citrus when examining broad combinations of limiting factors, phenological stages, and tissues (Guidetti-Gonzalez et al 2007). The putative methyltransferase DDB_G0268948 (Supporting information 5), has also been found highly expressed under Redox activity after Pseudomonas syringae pv tomato inoculation in a resistant tomato (Balmant et al 2015) and in Paulownia stress tolerance (Dong et al 2016).…”

“…The overall transcriptome information and candidate gene analysis revealed two different types of defense response. In the case of the inbred, the defense response was highly oriented into carbohydrate metabolism and monooxygenase activity (Figure 2), associated with a hypersensitive response (HR) (Birch et al 1999;Guidetti-Gonzalez et al 2007;Moeder et al 2002). However, in the case of the hybrid, a higher number of defense-related and recovery-related protein synthesis were expressed under stress conditions (i.e.…”

Identification of defence-related genes expressed in coffee and citrus during infection by Xylella fastidiosa

“…However, the presence of these transcripts solely in the RX1 library may be associated with the response to X. fastidiosa infection. Guidetti-Gonzalez et al (2007), analyzing the peroxidases from 33 citrus EST libraries, showed that some of them are constitutive, while others are induced by various stimuli. Interestingly, some of the contigs harboring peroxidase transcripts were composed by reads made solely from a library constructed from Xylellainfected citrus plants, indicating that they may be involved in the response of citrus to this pathogen.…”

“…They produce hydroperoxides that are converted into compounds involved in a variety of physiological processes such as plant development and biotic and abiotic stress adaptation (Liavonchanka and Feussnerm 2006). Although there are reports of increased LOX expression in compatible interactions (disease), it is more commonly associated with incompatible interactions, where it plays an important role in disease resistance, as observed in Citrus reticulata (a resistant citrus genotype) inoculated with X. fastidiosa (HR) (Guidetti-Gonzalez et al 2007). …”