Screening of Gametophytic Incompatibility in Maize with SSR Markers and Pollen-Mix Test.

Selection of heterozygote progenies with the gametophyte gene Ga1S in maize (Zea mays L.) relies on visual traits in the kernels that often are inaccurate. Our objective was to compare the efficiency of microsatellite markers and a pollen-mix test to screen for gametophytic incompatibility in maize. The inbred lines B114 and B125, and the breeding populations CH05 015:N12, CH05 015:Mo17, AR13 035:B73, Mo47/MRBC, and AR16 035:S19 were converted to be gametophytically incompatible through backcrossing. The recurrent and nonrecurrent parents, and the F1, were screened for genetic polymorphism with five simple sequence repeat (SSR) markers. Backcross progenies segregating for gametophytic incompatibility were identified by using a combination of a pollen-mix approach and genotyping with SSR markers. Only the marker umc1943 was polymorphic between the parents, and codominant in the F1 and backcrosses. Both methods were equally effective in the identification of heterozygotic individuals in backcrosses with both inbred lines and AR16 035:S19. Differences in genotype scores among some of the progenies of CH05 015:N12, CH05 015:Mo17, AR13 035:B73, and Mo47/MRBC were attributed to inaccuracy of the pollen-mix approach. We recommend selection of heterozygotic plants with the incompatibility trait be assisted with molecular markers.