Expression profiling and mapping of defence response genes associated with the barley–Pyrenophora teres incompatible interaction

Abstract

Barley net- and spot-form of net blotch disease are caused by two formae of the hemibiotrophic fungus Pyrenophora teres (P. t. f. teres and P. t. f. maculata). In the present study, suppression subtractive hybridization (SSH) was used in combination with quantitative real-time reverse transcriptase PCR to identify and profile the expression of defence response (DR) genes in the early stages of both barley-P. teres incompatible and compatible interactions. From a pool of 307 unique gene transcripts identified by SSH, 45 candidate DR genes were selected for temporal expression profiling in infected leaf epidermis. Differential expression profiles were observed for 28 of the selected candidates, which were grouped into clusters depending on their expression profiles within the first 48 h after inoculation. The expression profiles characteristic of each gene cluster were very similar in both barley-P. t. f. teres and barley-P. t. f. maculata interactions, indicating that resistance to both pathogens could be mediated by induction of the same group of DR genes. Chromosomal map locations for 21 DR genes were identified using four doubled-haploid mapping populations. The mapped DR genes were distributed across all seven barley chromosomes, with at least one gene mapping to within 15 cM of another on chromosomes 1H, 2H, 5H and 7H. Additionally, some DR genes appeared to co-localize with loci harbouring known resistance genes or quantitative trait loci for net blotch resistance on chromosomes 6H and 7H, as well as loci associated with resistance to other barley diseases. The DR genes are discussed with respect to their map locations and potential functional role in contributing to net blotch disease resistance.

SnTox1, a Parastagonospora nodorum necrotrophic effector, is a dual‐function protein that facilitates infection while protecting from wheat‐produced chitinases

“…The polysaccharide-binding assay for purified SnTox1-His was performed following a protocol described in van den Burg et al (2006) with minor modifications. The purified Avr4-His and SnTox3-His were used as positive and negative controls, respectively.…”

“…S2) was used to test polysaccharide-binding activity of SnTox1. CfAvr4 has been characterized as an effector that is beneficial to Cladosporium fulvum based on its ability to bind chitin to escape recognition (van den Burg et al, 2004Burg et al, , 2006. Therefore the purified Avr4-His and SnTox3-His were used as positive and negative controls, respectively.…”

“…Over the last three decades, the knowledge of plant-pathogen interactions has grown exponentially, partly as a result of the cloning of Avr and R genes as well as the characterization of the pathways involved in the host response to pathogen recognition and the pathogen's endeavors to conceal and protect itself during penetration and nutrient acquisition . As this area has developed, it has been shown in several cases that 'avirulence proteins' have a virulence function that allows the pathogen to remain undetected or provide protection from the host (van den Burg et al, 2006;Shabab et al, 2008;Houterman et al, 2009). Therefore, the term 'avirulence protein' has, for the most part, been replaced by the term 'effector', being defined as 'all pathogen proteins and small molecules that alter host-cell structure and function' (Hogenhout et al, 2009).…”

“…Studies have shown that hallmarks of the defense response are present in the susceptible reaction involving necrotrophic specialist pathogens. This defense response includes up-regulation of several defense response genes (Reiss & Bryngelsson, 1996;Reiss & Horstmann, 2001;Bogacki et al, 2008;Adhikari et al, 2009;Pandelova et al, 2009;Liu et al, 2012), electrolyte leakage (Rasmussen et al, 2004;Liu et al, 2015), DNA laddering (Dickman et al, 2001;Liu et al, 2012), and increases in reactive oxygen (Wolpert et al, 2002;Able, 2003;Liu et al, 2015), all during a susceptible interaction.…”

Transgene expression systems in the Triticeae cereals

“…Changes in the cereal transcriptome induced by pathogen attack have been studied by a range of molecular platforms (cDNA-AFLP: Zhang et al, 2003; suppression subtractive hybridization: Bogacki et al, 2008;array hybridization: Zellerhoff et al, 2010). Although these analyses have identified large numbers of differentially regulated genes, few of the relevant promoters have been functionally validated by transiently or stably expressed promoter/reporter gene fusions.…”