A Comprehensive Gene Expression Profile of Pectin Degradation Enzymes Reveals the Molecular Events during Cell Wall Degradation and Pathogenesis of Rice Sheath Blight Pathogen Rhizoctonia solani AG1-IA

Abstract

Sheath blight disease of rice caused by Rhizoctonia solani Kühn (teleomorph: Thanatephorus cucumeris) remains a global challenge due to the absence of reliable resistance genes and poor understanding of pathogen biology. Pectin, one of the most vital constituents of the plant cell wall, is targeted by pectin methylesterases, polygalacturonases, and few other enzymes of fungal pathogens. In this study, we catalogued the expressed genes of the fungal genome from RNAseq of R. solani infected four rice genotypes. Analysis of RNAseq revealed 3325 pathogen genes commonly expressed in all rice genotypes, in which 49, 490, and 83 genes were specific to BPT5204, Tetep, and Pankaj genotypes, respectively. To identify the early and late responding genes of R. solani during plant cell wall degradation, a real-time PCR analysis of 30 pectinolytic enzymes was done at six different time points after inoculation. The majority of these genes showed maximum induction at the 72 h time point, suggesting that it is the most crucial stage of infection. Pankaj showed lesser induction of these genes as compared to other genotypes. Leaf-blade tissue and 45 days old-growth stage are more favorable for the expression of pectin degradation genes of R. solani. Additionally, the expression analysis of these genes from four different strains of R. solani suggested differential regulation of genes but no distinct expression pattern between highly virulent and mild strains. The implications of the differential regulation of these genes in disease development have been discussed. This study provides the first such comprehensive analysis of R. solani genes encoding pectin degrading enzymes, which would help to decipher the pathogen biology and sheath blight disease development.

Cell-Wall-Degrading Enzymes-Related Genes Originating from Rhizoctonia solani Increase Sugar Beet Root Damage in the Presence of Leuconostoc mesenteroides

“…The higher expression of peroxidase and phytohormone-related genes (such as auxin, gibberellin) observed here possibly indicates their role in host defense at early infection stages (Table 2; Figure 5A). The similar role of some of these genes against other R. solani strains have been reported in diverse plant species, including soybean [25], potato [26], rice [27], and sugar beet [28,29]. Sugar beet genes were highly upregulated (up to 7-fold) by L. mesenteroides such as lipid-binding protein AIR1B (EL10Ac5g13046) and auxin-repressed 12.5 kDa protein isoform X1 (EL10Ac8g20421), which show bacterial pathogen-specific sugar beet responses (Table 2), whereas other highly upregulated (up to 348-fold) sugar beet genes, such as polygalacturonase inhibitor 1 (EL10Ac3g06968) and auxin-binding protein ABP19b-like (EL10Ac8g19076) highlight the global response of the sugar beet against fungal and bacterial pathogens (Table 2).…”

Genome-Wide Expression Profiling of Small RNAs in Indian Strain of Rhizoctonia solani AG1-1A Reveals Differential Regulation of milRNAs during Pathogenesis and Crosstalk of Gene Regulation

“…Compared to plants and animals, there are very limited reports on milRNAs of phytopathogenic fungi which are primary agents causing diseases and huge loss to agriculture crops. In the absence of resistance in the rice germplasm against R. solani, it is extremely important to decipher the gene regulatory networks and biology of pathogens to devise effective strategies for controlling the menace of sheath blight disease in rice [31,[33][34][35]. We analyzed the milRNAs of sheath blight disease causing pathogen R. solani AG1 IA by RNAseq of small RNAs.…”

“…The relative expression was calculated from 2 −∆∆Ct . The standard error was calculated as reported previously [31].…”

Review Update on the Life Cycle, Plant–Microbe Interaction, Genomics, Detection and Control Strategies of the Oil Palm Pathogen Ganoderma boninense

“…Other pathogenic fungi with similar modes of infection include Botrytis cinerea , Rhizoctonia solani and Sclerotinia sclerotiorum [ 44 , 45 ]. These pathogens produce small cell wall-degrading enzymes (CWDEs), including cellulase, laccase, polygalacturonase and manganese peroxidase, to soften and loosen the host cell wall without detrimentally affecting the host cells [ 46 ]. During early infection of the oil palm root, G. boninense hyphae will colonize the roots and secrete trace amounts of CWDEs, including polygalacturonase and laccase [ 47 , 48 ], to enable the establishment of a continued supply of nutrients from the living cells of their hosts.…”