Sources of genetic resistance in maize to Fusarium stalk rot and their variations at molecular level

Identifying the resistant genotypes is one of the vital strategies to control Fusarium stalk rot disease in maize. Fifty accessions of maize germplasm were evaluated for resistance to stalk rot caused by Fusarium verticillioides at the Maize and Millet Research Institute, Yousafwala, Pakistan, during the spring and autumn of 2010, and their genetic variations were also studied at the molecular level to avoid environmental effects in the Department of Medicinal Chemistry, University of Minnesota, USA. Disease severity was calculated in the field using a severity scale (SS) and direct estimation of stalk discoloration (SD) by artificial inoculation method. Both SS and SD results were highly significant (P < 0.01) in both seasons and maize accessions significantly differed in SS (P < 0.01) and SD (P < 0.01). Disease assessments based on SS and SD were significantly correlated (r = 0.983, 0.974; P < 0.01) in spring and autumn, respectively. Two genotypes, EL7 and Y11, showed highly resistant response in both growing seasons. Variations among the lines were also exploited by using 14 simple sequence repeat primer sets. A total of 535 alleles were amplified with an average of 10.7 alleles per genotype. The highest number of alleles per locus was seen with the xp-umc1186 primer, exhibiting 128 alleles with an average of 2.5 alleles per genotype. Resistance genotypes can be utilized in hybridization programs for the improvement of local high-yielding varieties.