Unravelling a genetic network for bolting time regulation in Beta species to breed winter sugar beet
Sugar beet is a biennial species bolting after exposure to extended cold. Therefore, field production with winter grown beets is impossible. However, winter beets could be an interesting alternative for beet production due to their higher yield potential. We have cloned two key regulators for bolting time control in beet, BTC1 and BvBBX19. We assume that both genes jointly regulate the expression of downstream targets such as BvFT1 and BvFT2. We will study the function of both genes in beet and after transformation into Arabidopsis thaliana in collaboration with two partners from the priority program. Transgenic beets overexpressing BTC1 start bolting after winter like common sugar beet. However, transgenic beets with >1 BTC1 copy generally failed to bolt probably due to BTC1 cosuppression. These results provided an incentive to breed winter beets. We will produce hybrids with low or absent BTC1 expression after crossing two BTC1 overexpression lines. Hybrid beets will be grown over winter in the climate chamber, in a gauzehouse (semi field conditions) and in the field. In a second approach we will produce double recessive beets (btc1 and Bvbbx19) with severely delayed bolting after winter. Those beets could be grown worldwide without legal restrictions because they are non-transgenic. Moreover, we will collaborate in a ‘phylotranscriptomics’ experiment with another partner in the frame of PP1530 to grow sugar beet under standardized conditions in the climate chamber.
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