Transcriptomic Dynamics of Active and Inactive States of Rho GTPase MoRho3 in Magnaporthe oryzae

Abstract

The small Rho GTPase acts as a molecular switch in eukaryotic signal transduction, which plays a critical role in polar cell growth and vesicle trafficking. Previous studies demonstrated that constitutively active (CA) mutant strains, of MoRho3-CA were defective in appressorium formation. While dominant-negative (DN) mutant strains MoRho3-DN shows defects in polar growth. However, the molecular dynamics of MoRho3-mediated regulatory networks in the pathogenesis of Magnaporthe oryzae still needs to be uncovered. Here, we perform comparative transcriptomic profiling of MoRho3-CA and MoRho3-DN mutant strains using a high-throughput RNA sequencing approach. We find that genetic manipulation of MoRho3 significantly disrupts the expression of 28 homologs of Saccharomyces cerevisiae Rho3-interacting proteins, including EXO70, BNI1, and BNI2 in the MoRho3 CA, DN mutant strains. Functional enrichment analyses of up-regulated DEGs reveal a significant enrichment of genes associated with ribosome biogenesis in the MoRho3-CA mutant strain. Down-regulated DEGs in the MoRho3-CA mutant strains shows significant enrichment in starch/sucrose metabolism and the ABC transporter pathway. Moreover, analyses of down-regulated DEGs in the in MoRho3-DN reveals an over-representation of genes enriched in metabolic pathways. In addition, we observe a significant suppression in the expression levels of secreted proteins suppressed in both MoRho3-CA and DN mutant strains. Together, our results uncover expression dynamics mediated by two states of the small GTPase MoRho3, demonstrating its crucial roles in regulating the expression of ribosome biogenesis and secreted proteins.

Improved Cellulase Production of Trichoderma reesei by Regulating Mycelium Morphology

“…RhoB also contributes to cell wall integrity in Neurospora crassa, Arthrobotrys oligospora, and Fusarium graminearum [13,14,18]. While RhoC had no obvious function in A. niger [9], its homolog is involved in growth, conidiation, and virulence in Botrytis cinerea [19], secretion process in T. reesei [20], appressorium formation and polar growth in M. oryzae [21], and vegetative growth and conidiation in F. graminearum [14], as well as cell polarity and hyphal morphogenesis in A. gossypii [10]. RhoD is required for sporulation, septum formation, and cell wall integrity in A. niger and A. nidulans [9,22], hyphal growth, conidiation, and septum formation in F. graminearum [14], septum formation, hyphal tip growth, and possibly cell wall integrity in N. crassa [23,24], and cell wall integrity and virulence in Colletotrichum graminicola [25].…”

Special Issue “Genomics of Fungal Plant Pathogens”

“…The small Rho GTPase family regulates most fundamental processes of eukaryotic cells, including (but not limited to) morphogenesis, polarity, movement, cell division, gene expression and cytoskeleton reorganization [9,10]. In order to elucidate the function of the small GPTase MoRho3 in M. oryzae, Li et al [11] performed comparative transcriptomic analysis of MoRho3 constitutively active mutant (MoRho3-CA) and MoRho3 dominant-negative mutant (MoRho3-DN). In MoRho3-CA vs. WT, about 874 up-regulated, differentially expressed genes (DEGs) were detected, and the DEGs were significantly enriched in the ribosome biogenesis pathway, while 1511 down-regulated DEGs were also detected and were enriched in different amino acids and chemical metabolism pathways.…”