Suppression subtractive hybridization and comparative expression of a pore-forming toxin and glycosyl hydrolase genes in Rhizoctonia solani during potato sprout infection

Abstract

Rhizoctonia solani is a plant pathogenic fungus that causes black scurf on tubers and stem and stolon canker on underground parts of potato plant. Early in the season, the fungus attacks germinating sprouts underground before they emerge from the soil. Damage at this stage results in delayed emergence of weakened plants with poor and uneven stands. The mechanism underlying this phenomenon has been investigated in this study by coupling a cDNA-suppression subtractive hybridization (SSH) library to differential screening to identify transcripts of R. solani that are down-regulated during infection of potato sprouts. We report on the identification of 33 unique genes with functions related to carbohydrate binding, vitamin synthesis, pathogenicity, translation, ATP and nucleic acid binding and other categories. RACE-PCR was used to clone and characterize the first full-length cDNA clones, RSENDO1 and RSGLYC1 that encode for an eukaryotic delta-endotoxin CytB protein and an intracellular glycosyl hydrolase, respectively. Quantitative real-time PCR revealed the down-regulation of RSENDO1 during infection of potato sprouts and the up-regulation of RSGLYC1 when the fungus was grown on a cellulose-based nutrient medium. In contrast, additional experiments have highlighted the down-regulation of RSENDO1 when R. solani was co-cultured with the mycoparasite Stachybotrys elegans and the bacterial antagonist Bacillus subtilis B26. These results advance our understanding of R. solani-potato interaction in subterranean parts of the plant. Such approaches could be considered in building an efficient integrated potato disease management program.

Transcriptomic changes in the plant pathogenic fungus Rhizoctonia solani AG-3 in response to the antagonistic bacteria Serratia proteamaculans and Serratia plymuthica

“…It has been reported that similar proteins can be found in other pathogenic fungi and bacteria suggesting a potential role of these proteins in the virulence of these microorganisms [ 62 ]. Interestingly, it has been recently shown that when R. solani AG3 was co-cultured with the soil-inhabiting bacterial antagonist Bacillus subtilis and with the mycoparasite Stachybotrys elegans , RSENDO1 gene encoding a delta-endotoxin CytB gene was downregulated in contrast to the upregulation shown in our study [ 13 ]. A gene containing the ricin b-like lectin domain involved in the production of the highly toxic legume lectin ricin was also highly upregulated almost 16 times in both treatments.…”

Genome analysis of the sugar beet pathogen Rhizoctonia solani AG2-2IIIB revealed high numbers in secreted proteins and cell wall degrading enzymes

“…The primers used in this study are listed in Additional file 12 : Table S7. Expression of genes was normalized by G3PDH expression [ 68 ] and relative expression values were calculated according to the 2 -∆∆Ct method [ 69 ]. Analysis of variance (ANOVA, one way) was conducted on gene expression and phenotypic data using a General Linear Model implemented in SPSS ver.…”

Reactive Oxygen Species Play a Role in the Infection of the Necrotrophic Fungi, Rhizoctonia solani in Wheat

“…Recently a number of studies have used gene expression analysis to study specific aspects of R . solani biology, including during sclerotia formation [ 30 ], the response to antagonistic bacteria [ 31 ], and during infection of different hosts looking at the plant [ 15 ] or pathogen side [ 32 , 33 ] of the interaction. In this study we have investigated the interaction between wheat and R .…”