Identification, molecular characterization and analysis of the role of MORC gene family in disease resistance mechanisms to biotrophic and necrotrophic fungi in barley
World agriculture today faces many challenges owing to global climate change and aberrantweather phenomenon. A concomitant result of this abiotic change has been the spread andincrease of plant diseases and associated disease causing agents that has put world foodsecurity under serious threat, especially in developing countries. Under these challengingcircumstances, alternatives to conventional crop protection strategies have gained worldwideattention in recent years. Our study here highlights one such strategy that depends on MORCgene family which is widely distributed throughout eukaryotes and in many plant species.Altered expression of MORCs affected plant resistance to pathogens wherein overexpressionof HvMORC1 increased susceptibility to barley powdery mildew and RNAi-mediatedsilencing of HvMORC2 resulted in enhanced resistance to this biotrophic pathogen.Additionally, HvMORC2 silencing also confers basal resistance to necrotrophic pathogenFusarium graminearum; a finding which might have interesting agricultural applications as itis considered to be a devastating cereal pathogen and robust broad spectrum resistanceagainst Fusarium diseases are yet to be identified. The HvMORC protein is described toreside in the nucleus and is shown to have interesting biochemical properties such as DNAbinding and endonuclease activity further fuelling speculation that MORCs have an importantnuclear role such as chromatin remodelling that might contribute to different phenotypesobserved. Finally, barley MORCs have contrasting function to their Arabidopsis counterparts.Even though they are closely related proteins with very similar structural domains andenzymatic properties, the Arabidopsis MORC seems to act as a positive regulator of plantdefense mechanisms while barley MORC has a negative regulatory role in plant immunity.What is even more interesting, they failed to complement each other s function whenexpressed in reciprocal systems and retained their functions despite change in biologicalsystem and their biochemical environment. These results let us speculate that the contrastingeffects observed are species specific and might be the properties of the proteins themselves.A further, detailed molecular and biochemical analysis of these genes might offer a brighterinsight into this exciting topic. Nevertheless, the MORC gene family has tremendouspotential for agricultural applications as they have also been identified in other importantcereal crops like rice, wheat (Triticum aestivum) and maize (Zea mays) a staple for aboutthree quarter of world s population. Studies in some of the other plant systems would addvaluable information to our current understanding of MORCs and help engineer resistance ineconomically important crop plants.
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