Monosomic addition lines of Beta corolliflora in sugar beet:: plant morphology and leaf spot resistance

Monosomic addition lines in Beta vulgaris from Beta corolliflora were described morphologically and characterized for disease resistance. Monosomic addition plants (2n = 19) were selected among segregating offspring by a squash dot technique in combination with B. corolliflora-specific probes. Plants carrying an added chromosome were characterized by leaf shape, plant size and plant viggour. In this way, most addition lines could be distinguished from diploid beets, however, to identify these plants unequivocally, molecular marker analysis was also necessary. Transmission frequencies of cacti addition line were determined to be in the range 13.9% (Cor-4) to 60% (Cor-9). Hig transmission rate of addition line Cor-9 was assumed to be due to apomictic propagation because transmission rate after selfing cannot exceed 50%. Cercospora leaf spot resistance tests were performed on 167 monosomic plants from seven different addition lines, two fragment addition lines and 89 diploid controls. No line exhibited complete resistance, but the monosomic additions Cor-3 and Cor-4 showed significantly lower infection rates than their diploid sibling plants. The identification of monosomic addition lines with apomictic and disease resisitance characters offers the possibility of transferring those genes to sugar beet.