Determination of Viral Titer and Symptom Severity Variations in Maize Chlortic Mottle and Sugarcane Mosaic Virus Infected Maize Genotypes in Ethiopia

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Addis Ababa University


The co-infection of Maize chlorotic mottle virus (MCMV) and Sugarcane mosaic virus (SCMV) can cause maize lethal necrosis. Though some studies were conducted to determine the incidence of MCMV and SCMV in Ethiopia, the role of their synergistic interaction in enhancing the severity of MLND in Ethiopian maize genotypes received little attention. This study was, therefore, designed to determine the role of MCMV and SCMV interaction in enhancing the severity of MLND in eight Ethiopian maize genotypes. Symptomatic leaves suspected with MCMV and SCMV infection were collected from different parts of Ethiopia. Eight maize genotypes (Melkassa 1, Melkassa 2, Melkassa 4, MH 140, MH 130,MHQ 138, Jibat and CML 445) were also obtained from Melkassa Agricultural Research Center (MARC). The collected leaves were checked for MCMV and/or SCMV infectionby DAS ELISA method. RNA was extracted from each leaf sample using HiPurA plant and fungal RNA Miniprep purification kit. The extracted RNA was then confirmed by RT PCR. Symptom severity was also determined by standard scores. The mean MCMV titer was significantly higher in five of the maize genotypes (Melkassa4, MH140, MH130, CML445 and Jibat) infected by both MCMV and SCMV than those infected by MCMV alone (P<0.05 for all). In contrast, there were no significant differences in mean MCMV viral titer between MCMV and MCMV-SCMV infected genotypes in Melkassa 1 (P=0.860), Melkassa 2 (P=0.572) and MHQ138 (P=0.734). Although higher mean SCMV titer was found in all genotypes infected by SCMV than those co-infected by SCMV and MCMV, the difference was not statistically significant (P>0.05 for all).As compared to the other genotypes lower score symptom severity was observed in Melkassa 1 and Melkassa 2. This study, therefore, revealed that on the basis of viral titer and symptom severity used to determine disease response, Melkassa 1 and Melkassa 2 have high resistance to MLND. Moreover, MH 138 was also found to have higher resistance to increment in viral titer than the other genotypes. These resistant genotypes might serve as markers for further investigation of resistant maize genotypes in Ethiopia.



DAS ELISA, Maize Genotypes, Maize Lethal Necrosis Disease, RT-PCR, Symptom Severity