Abstract:
Contrast between marker-assisted backcross (MABC) and
doubled haploid (DH) methods in transferring genes for resis tance to maize lethal necrosis (MLN) in maize (Zea mays L.) is
not well understood. The MLN is caused by co-infection of
maize plant by maize chlorotic mottle virus and sugarcane
mosaic virus. Two maize panels consisting of four BC3F2 and
six DH populations, separately developed through marker assisted selection from crosses between susceptible CIMMYT
lines and MLN-resistant donor parent (KS23-6), were used in
the current study. The two populations were of different popu lation structures with unequal sizes. Experiments were con ducted under artificial MLN inoculations for two seasons in
2018. Analyses of variance revealed significant variations
among genotypes in both panels (p ≤ 0.001). Levene’s and
Welch’s tests found that variances and means of the BC3F2 and
DH populations were highly unequal (p ≤ 0.001). The study
identified genotypes with reduced MLN infections in both
populations; however, lower means for MLN severity and area
under disease progress curve (AUDPC) values, and higher her itability estimates were obtained in the DH populations than in
the BC3F2 populations. Additionally, the DH populations
showed higher relative genetic gains for resistance to MLN
compared with the BC3F2 populations. The current study
detected superiority of DH over MABC populations for breed ing for resistance to MLN. Nevertheless, the results observed in
the present study warrant further investigations using the
same genetic materials with identical population sizes.
