Unraveling a mechanism for floral transition control in annual, biennial, and perennial Beta species
The species Beta vulgaris includes annual, biennial, and perennial accessions.
Annual beets germinate, bolt, and flower within one season. Biennial beets such as sugar beets need prolonged exposure to cold temperatures to acquire floral competence. After seed production, annual and biennial beets senesce and die. By contrast, perennial beets live several years and repeat flower onset each year or bolt earliest in the third season.
We hypothesize that there is at least one common flowering time gene which is responsible for bolting induction in annual, biennial, and perennial beets and that the different regulation of this gene (these genes) distinguishes between annual and perennial growth. Allelic variants of this gene (genes) may also be responsible for bolting failure in non-bolting Beta plants. Using genome-wide transcriptome and quantitative real-time PCR analyses, we will identify floral transition genes that induce bolting and floral competence in beets with different phenology. In order to detect loci that are responsible for perennial growth, a QTL analysis will be performed using Beta populations segregating for annual and iteroparous perennial growth. Subsequently, candidate genes determined by the transcriptome analysis will be mapped and tested for co-localization with detected QTLs to identify the common bolting inducing gene as well as genes responsible for longevity and repeated flowering. Additionally, we will clone genes that are responsible for bolting failure in perennials by a bulked segregant sequencing approach using a Beta population that segregates for biennial and non-bolting perennial plants. The identification of bolting control and bolting failure genes will allow to control the timing of flowering and to create a genetic tool for targeted manipulation of bolting and flowering time in sugar beet.