Abstract
Background: Maize lethal necrosis (MLN) disease continues to reduce the productivity of maize drastically threatening food security in the affected regions. It continues to cause yield loss of 30–100 percent in farmers’ fields, depending on the time of infestation which is valued at $198 million in Kenya. This has not only threatened regional trade, but also seed industry. It has been reported in the major maize belts of Uasin Gishu, Trans-Nzoia, Bomet, Narok and Nandi Counties. MLN is caused by the synergistic interaction between Sugarcane Mosaic Virus (SCMV) and Maize Chlorotic Mottle Virus (MCMV). The disease has then spread to other Eastern and Central African countries with devastating food security and economic consequences. Objectives: This study highlights result after screening selected maize inbred lines for resistance to MLN, SCMV and MCMV in identifying promising lines for integration into the breeding program for MLN resistance. Methods: Sixty-five (65) maize genotypes were artificially inoculated using virus strains collected from Bomet County in Kenya at 3-4 leaf stage. Data on disease severity and incidence, AUDPC and flowering were recorded. Results: From the result, the inbred lines had significant differences for SCMV, MCMV and MLN reactions. Based on Area Under Disease Progress Curve (AUDPC) score and ELISA analysis, genotypes MLN001 and MLN006 have the lowest score of 270, whereas OH28 had a maximum at 1259 under MCMV. Genotypes MLN042 and MLN041 were identified as the most promising sources of resistant against SCMV. However, no genotype was identified to have acceptable levels of tolerance to MLN, but MLN001 and MLN013 were identified as the best performers under MLN. This study also validated the presence of MLN tolerance in MLN013 (CKDHL120312) and MLN001 (CKDHL120918) as earlier reported by CIMMYT. These tolerant genotypes are now serving as donors in the introgression of the tolerance into the Kenyan adapted maize backgrounds and development of improved MLN tolerant varieties. This will go a long way in restoring and ensuring sustainable maize productivity in improving the livelihoods of the smallholder farmers who form 75% of the major maize producers in Kenya. Conclusion: The identified inbred lines would be recommended for use in varietal development, MLN management and to enhance maize productivity, in the MLN endemic regions and further research in understanding the mode of gene action for MLN tolerance.
Highlights
Maize accounts for > 20% of total agricultural production, and 25% of agricultural employment in Kenya [1]
X Oh920) X (I11.A x I11.B) which was released in 1943 [22]. and it is susceptible to Maize dwarf mosaic virus (MDMV), Sugarcane Mosaic Virus (SCMV), Wheat streak mosaic virus (WSMV), Maize chlorotic dwarf virus (MCDV), Maize mosaic virus (MMV), and Maize fine streak virus (MFSV) [23 - 25, 14]was used as a susceptible check while N211 and KS23-6 were used as tolerant checks for both Maize Chlorotic Mottle Virus (MCMV) and Maize lethal necrosis (MLN) [12]
Evaluation of the germplasm suggests that MLN041 and MLN042 may be carrying the desirable genes for SCMV resistance and MLN001, MLN006, MLN016 and N211 for MCMV tolerance
Summary
Maize accounts for > 20% of total agricultural production, and 25% of agricultural employment in Kenya [1]. Earlier the disease was observed in Kansas, USA, in 1978 Niblett and Claflin where it was identified as corn lethal necrosis (CLN) disease [7] Both MLN and CLN are caused by double infection of maize plants by maize chlorotic mottle virus (MCMV) (Machlomovirus: Tombusviridae) in combination with any of the cereal viruses in the Potyviridae group, Sugarcane mosaic virus (SCMV) (Potyvirus: Potyviridae), Maize dwarf mosaic virus (MDMV) or Wheat streak mosaic virus (WSMV). Maize lethal necrosis (MLN) disease continues to reduce the productivity of maize drastically threatening food security in the affected regions. It continues to cause yield loss of 30–100 percent in farmers’ fields, depending on the time of infestation which is valued at $198 million in Kenya. The disease has spread to other Eastern and Central African countries with devastating food security and economic consequences
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