| Popis: |
The timing of flowering and inflorescence architecture are critical for the reproductive success of tomato, but the gene regulatory networks underlying these traits have not been fully explored. Here we show that the tomatoFRUITFULL-like (FUL-like) genesFUL2andMADS-BOX PROTEIN 20 (MBP20)induce flowering and repress inflorescence branching by promoting floral meristem determinacy.FUL1fulfils a less prominent role and appears to depend on FUL2 and MBP20 for its upregulation in the inflorescence- and floral meristems.MBP10, the fourth tomatoFUL-like gene, has probably lost its function. The tomato FUL-like proteins cannot homodimerize inin vitroassays, but heterodimerize with various other MADS-domain proteins, potentially forming distinct complexes in the transition meristem and floral meristem. Transcriptome analysis of the primary shoot meristems revealed various interesting downstream targets, including four repressors of cytokinin signalling that are upregulated during the vegetative-to-reproductive transition inful1 ful2 mbp10 mbp20mutants. FUL2 and MBP20 can also bindin vitroto the upstream regions of these genes, thereby probably directly stimulating cell division in the meristem upon the transition to flowering. The control of inflorescence branching does not occur via the CKXs, but appears regulated by repression of transcription factors such asTM3, APETALA 2b(AP2b) andAP2a. |
