Search

Blast disease caused by Magnaporthe species is a major threat to the productivity of agriculturally important cereal crops including rice, pearl millet, wheat, oats, barley and minor millets etc. Two major species of Magnaporthe , viz. M. oryzae and M. grisea cause approximately 10–30% annual yield loss in their respective host crop. Imparting long-term resistance in the host necessitates the detailed knowledge on the molecular basis of pathogen virulence factors. Thus, here we have made an attempt to characterize the virulence factors (VFs) from M. grisea strain PMg-Dl in comparison to M. oryzae strain RMg-Dl. The functional gene ontology annotation revealed predominance of membrane system (GO: 0016020, GO:0016021), ion-binding system (GO:0043167; metal binding GO:0046872; zinc ion binding GO:0008270) etc. Further, in silico domain analysis of eight uncharacterized preferential virulence factor genes, viz. MBSD02000619.1.g3349 , MBSD02000495.1.G5524 , and MBSD02000009.1.G8852 and Mg.00g031250.m01, Mg.00g080210.m01, Mg.00g080580.m01, Mg.00g034390.m01 and Mg.00g016130.m01 showed the target genes belongingness to MFS family, integrase, protease, transcription factors etc. The PCR analysis showed the presence of eight target VFs in the Magnaporthe isolates infecting rice, pearl millet, finger millet and other grasses, respectively. The functional analysis of uncharacterized target preferential virulence factor genes (M. oryzae :3; M. grisea: 5) in three host systems viz., rice, pearl millet and finger millet at eight different time points confirmed their role as virulence factors in Magnaporthe system. The results are useful in further dissecting the Magnaporthe -host interactions by gene knock-out and knock in approaches through transgenics and genome editing to develop resistant cultivars soon. • Eight potential uncharacterized virulence factors (VFs) were identified from Magnaporthe species. • Each VFs was a part of different protein family including MFS, integrase, receptor etc. • The functional analysis of hypothetical genes confirmed their role as virulence factors in Magnaporthe system. • VFs genes plays a key role in modulating the blast susceptibility in rice, pearl millet and finger millet hosts. [ABSTRACT FROM AUTHOR]

Abstract: In order to understand the defense machinery in the model cereal crop rice, we performed a large-scale analysis of rice gene expression in response to rice blast Magnaporthe grisea (M. grisea) or Magnaporthe oryzae and bacterial blight Xanthomonas oryzae pv. oryzae (Xoo) during the early incompatible and compatible interactions. Using a gene chip containing 10254 rice cDNAs representing 9240 unique genes, we identified 794 and 612 genes differentially expressed in the incompatible and compatible rice–M. grisea interactions, respectively, with 274 genes co-regulated during both interactions. In the rice–Xoo pathosystem, 454 and 498 differentially expressed genes were identified in the incompatible and compatible interactions, respectively, including 237 co-regulated genes in the both interactions. By clustering differentially regulated genes from all these interactions, we identified 29 co-regulated genes in the all four interactions, and 86 and 74 co-regulated genes in the two incompatible and two compatible interactions, respectively. These differentially expressed genes could be classified into three categories, including M. grisea- and Xoo-regulated, M. grisea-specific, and Xoo-specific. The expression patterns of representative defense-related genes were further confirmed by RT-PCR. The large-scale expression data from our microarray analysis indicated the existence of distinctive as well as shared defense pathways between the rice–M. grisea and rice–Xoo interactions. [Copyright &y& Elsevier]