Microsatellite DNA analysis of corn (Zea mays L.) inbred lines selected for downy mildew resistance
2014
Fernandez, E.C.J. | Galvez, H.F. | Canama, A.O. | Lantican, D.V. | Quilloy, R.B. | Ripalda, R.R.
The genetic diversity of nine downy mildew resistant (DMR) inbred lines of corn was analyzed using bulked DNA samples with 19 SSR markers. Selected resistant and susceptible parental lines and control genotypes were also included in the analysis. These SSR markers were identified based on genetic map positions in the maize genome and to represent each chromosomal region. Furthermore, the inheritance of a QTL marker for DMR was also validated in all of these corn resistant lines. Based on Nei-Li's similarity coefficient (NT SYSPC 2.1), DMR lines 19, 4 and 2 are genetically most similar to the elite but susceptible parental genotype. This is further supported with the average number of recurrent parent alleles recovered as screened with seven SSR markers at generations BC1F2 and BC1F6/F7 of these corn inbred lines. With regards to DMR, only corn lines 9, 4, 7 and 11 are validated for the stable inheritance of the DMR-QTL marker up to BC1 F6/F7 generation. This reinforces the control of several QTLs in conferring effective resistance aside from the DMR-QTL tracked in this study. De-bulking of the DNA pools and re-validation of SSR/molecular marker analysis is being done in order to derive quantitative parameters for genetic diversity as effective number of alleles (Ae) and average expected heterozygosity (He). The results of this study provide predictive genetic parameters to identify which among the DMR lines can be selected as best parental lines in hybridization breeding programs of corn for downy mildew resistance.
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