HYBRIDIZATION BETWEEN BETA VULGARIS AND B. PROCUMBENS AND TRANSMISSION OF NEMATODE (HETERODERA SCHACHTII) RESISTANCE TO SUGARBEET

Abstract

Triploid hybrids between tetraploid Beta vulgaris (4x = 36) and diploid B. procumbens (2x = 18) were used to transmit nematode resistance into sugarbeet. In meiosis of triploid hybrids, nine B. vulgaris bivalents and nine B. procumbens univalents were usually observed. In some pollen mother cells (PMC's) trivalent associations (8II + 8I + 1III) were formed. The second anaphase varied from near regular to very irregular. The regular anaphase produced normal quartets and viable gametes.The B1 plants and the plants of all succeeding backcross generations were tested for nematode resistance. From 6,750 B1 plants, four nematode-resistant trisomics were selected that had 18 B. vulgaris chromosomes and one B. procumbens chromosome responsible for resistance. The B. procumbens chromosome and nematode resistance were transferred to the eighth backcross generation with an average transmission rate of 12%. In meiosis of trisomies, trivalent associations of two B. vulgaris and one B. procumbens chromosomes were formed in a few PMC's. Two diploid nematode-resistant plants were selected from 8,834 backcross plants in the progenies of trisomies, and resistance was transferred from both of these plants to F1 hybrids. The segment of the B. procumbens chromosome bearing the gene for nematode resistance has been transferred to a sugarbeet chromosome.