Analysis of genes that are differentially expressed during the Sclerotinia sclerotiorum–Phaseolus vulgaris interaction

Abstract

The fungus Sclerotinia sclerotiorum (Lib.) de Bary, one of the most important plant pathogens, causes white mold on a wide range of crops. Crop yield can be dramatically decreased due to this disease, depending on the plant cultivar and environmental conditions. In this study, a suppression subtractive hybridization cDNA library approach was used for the identification of pathogen and plant genes that were differentially expressed during infection of the susceptible cultivar BRS Pérola of Phaseolus vulgaris L. A total of 979 unigenes (430 contigs and 549 singletons) were obtained and classified according to their functional categories. The transcriptional profile of 11 fungal genes related to pathogenicity and virulence were evaluated by reverse transcription quantitative real-time polymerase chain reaction (RT-qPCR). Additionally, the temporal expression profile obtained by RT-qPCR was evaluated for the following categories of plant defense-related genes: pathogenesis-related genes (PvPR1, PvPR2, and PvPR3), phenylpropanoid pathway genes (PvIsof, PvFPS1, and 4CL), and genes involved in defense and stress-related categories (PvLox, PvHiprp, PvGST, PvPod, and PvDox). Data obtained in this study provide a starting point for achieving a better understanding of the pathosystem S. sclerotiorum–P. vulgaris.

Changes in the Sclerotinia sclerotiorum transcriptome during infection of Brassica napus

“…Although the aspS gene was not up-regulated in the current study, genes encoding proteases similar to aspS (SS1G_05329 and SS1G_02870), were up-regulated at the very early stages of the infection in support of the previous studies. However, a gene encoding another aspartyl protease , SS1G_03181, was also detected in the S. sclerotiorum – P. vulgaris interaction with increased expression at the spreading necrosis stage [40]. SS1G_03181 was up-regulated at 24-48 hpi in the current study which is in agreement with these earlier findings.…”

“…They suggested that since SsPG1 expression was also induced by carbon starvation and repressed by galacturonic acid that it may be involved in both early penetration events and lesion expansion. During Phaseolus vulgaris infection, SsPG1 is induced during the later stages of the interaction (48-72 hpi), SsPG 3 is up-regulated earlier at 12 hpi, while SsPG6 exhibits a bimodal pattern with peaks of expression at 6 and 48 hpi [40]. SsPG3 and SsPG6 are also potent inducers of light-dependent necrotic reactions [54].…”

“…Both proteins share a 30 amino acid region associated with necrotizing activity [57]. In the S. sclerotiorum – P. vulgaris interaction, SS1G_01493 (beta-xylosidase) was up-regulated during the early stages before the emergence of visible necrotic symptoms on the stem, whereas genes encoding cellulose-degrading enzymes, SS1G_13255 (beta-1,4-glucanase) and SS1G_07146 (cellobiohydrolase), were induced during the later stages of infection coinciding with the formation of visible stem lesions [40]. In B. cinerea , the expression patterns of genes encoding xyloglucan-degrading enzymes was found to be vastly different dependent upon the host plant [58].…”

“…The expression of this gene only at the necrotic stage is in support of the previous study. During infection of P. vulgaris , acp1 is first induced during the very early stages of the infection and then again at the later stages [40]. The expression of acp1 is regulated by several environmental factors including glucose and nitrogen starvation and acidification.…”

“…Subsequently, microarray [36] and RNA-Seq analysis [37] was used to explore the B. napus responses to S. sclerotiorum . The release of the S. sclerotiorum genome sequence [38] in combination with next generation sequencing has allowed for in-depth analysis of the S. sclerotiorum - pea [39], S. sclerotiorum - Phaseolus vulgaris [40] and S. homoeocarpa - creeping bentgrass [41] pathosystems. Proteomic analysis of exudates from liquid cultures has identified several secreted proteins that may be involved in aspects of pathogenesis [42].…”