Project description:Brassica oleracea var. botrytis, a very popular crop grown for its edible inflorescence, is bred only as a mutated annual cultivar and does not naturally occur in environment. Since cauliflower is still described as the most troublesome of all the B. oleracea vegetables regarding transformation processes, it is fully justified to focus on the improvement of tools for its genetic modifications. Here, we present a successful protocol for genetic transformation of cauliflower employing the process of agroinfection. The primary analysis of in vitro response of five cultivars allowed us to have chosen Pionier as the most promising cultivar; in consequence the Pionier was transformed via Rhizobium-mediated techniques in order to evaluate both, R. radiobacter (EHA 105, LBA 4404) and R. rhizogenes (ATCC 18534, A4) species. However, the latter system turned out to be more effective and, the A4 strain, in particular (72% transformation efficiency, 55% confirmed by GUS assay). That shows a promising technical advance especially when compared to the results of previous literature reports (e.g. 8.7% reported efficiency using R. rhizogenes). The transgenic cauliflower was obtained from hairy roots via organogenic callus induction. The potential transformants were analysed at the genomic and proteomic levels and their transgenic character was fully confirmed.
Project description:In agricultural species that are sexually propagated or whose marketable organ is a reproductive structure, management of the flowering process is critical. Inflorescence development in cauliflower is particularly complex, presenting unique challenges for those seeking to predict and manage flowering time. In this study, an integrated physiological and molecular approach was used to clarify the environmental control of cauliflower reproductive development at the molecular level. A functional allele of BoFLC2 was identified for the first time in an annual brassica, along with an allele disrupted by a frameshift mutation (boflc2). In a segregating F? population derived from a cross between late-flowering (BoFLC2) and early-flowering (boflc2) lines, this gene behaved in a dosage-dependent manner and accounted for up to 65% of flowering time variation. Transcription of BoFLC genes was reduced by vernalization, with the floral integrator BoFT responding inversely. Overall expression of BoFT was significantly higher in early-flowering boflc2 lines, supporting the idea that BoFLC2 plays a key role in maintaining the vegetative state. A homologue of Arabidopsis VIN3 was isolated for the first time in a brassica crop species and was up-regulated by two days of vernalization, in contrast to findings in Arabidopsis where prolonged exposure to cold was required to elicit up-regulation. The correlations observed between gene expression and flowering time in controlled-environment experiments were validated with gene expression analyses of cauliflowers grown outdoors under 'natural' vernalizing conditions, indicating potential for transcript levels of flowering genes to form the basis of predictive assays for curd initiation and flowering time.
