doi:10.1038/nindia.2017.6 Published online 20 January 2017
Researchers have identified the underlying signaling pathway that provides disease resistance to rice against the leaf blight bacteria Xanthomanas oryzae1. They suggest that instead of relying on pesticides, this signaling system could be exploited to stimulate the plant defense mechanism and weaken the bacteria.
The researchers studied the mitogen activated protein kinases (MAPK) signaling in rice and how it confers resistance against the bacteria notorious for causing leaf blight disease. The widely-studied MAPK signaling cascade gets activated during both biotic and abiotic stress in plants.
Pathogens have evolutionarily conserved structures recognized by receptors on the plant outer membrane. These receptors, when activated, cascade a signaling trigger that abates the pathogen. Alok Krishna Sinha and Siddhi K Jalmi at the National Institute of Plant Genome Research in New Delhi have been working on understanding such signaling and the plant’s counter response when the pathogen challenges a rice host.
They looked at the role of three members of the MAPK family – OsMKK3, OsMPK7 and OsWRK30 – in the plant’s immune response against Xanthomonas oryzae. When OsMPK7 was over expressed, the researchers saw a marked decrease in lesions caused by the pathogen. Over expression of OsMKK3 and OsWRK30 also helped in conferring resistance. Sinha says this can be attributed to the activation of immune response genes and strengthening of the cell wall.
Silencing of these MAPK members causes an increase in disease conditions. The researchers now plan to extend the experiments, performed in greenhouse conditions, to transgenics that over-express OsMPK7 in field conditions.
1. Jalmi, S. K. & Sinha, A. K. Functional involvement of a Mitogen Activated Protein Kinase module, OsMKK3-OsMPK7-OsWRK30 in mediating resistance against Xanthomonas oryzae in rice. Sci. Rep. 6, 37974 doi: 10.1038/srep37974 (2016)