GENETIC-BASIS OF RESISTANCE TO SUGARCANE MOSAIC-VIRUS IN EUROPEAN MAIZE GERMPLASM

Sugarcane mosaic virus (SCMV) causes considerable damage to maize (Zea mays L.) in Europe. The objective of the present study was to determi ne the genetic basis of resistance to SCMV in European maize germplasm and to compare it with that of U.S. inbred Pa405. Three resistant Eur opean inbreds D21, D32, and FAP1360A were crossed with four susceptibl e inbreds F7, KW1292, D408, and D145 to produce four F-2 populations a nd three backcrosses to the susceptible parent. Screening for SCMV res istance in parental inbreds and segregating generations was done in tw o field trials as well as under greenhouse conditions. RFLP markers um c85, bnl6.29, umc10, umc44, and SSR marker phi075 were used in F-2 pop ulations or F-3 lines to locate the resistance gene(s) in the maize ge nome. Segregation in the F-2 and backcross generations fitted to diffe rent gene models depending on the environmental conditions and the gen otype of the susceptible parent. In the field tests, resistance in the three resistant European inbreds seems to be controlled by two to thr ee genes. Under greenhouse conditions, susceptibility to SCMV in D32 a ppears to be governed by one dominant and one recessive gene. Allelism tests indicated the presence of a common dominant gene (denoted as Se mi) in all three resistant European inbreds and Pa405. Marker analyses mapped two dominant genes: Semi on chromosome 6S and Scm2 on chromoso me 3.