Over-expression of a conserved RNA-binding motif (RRM) domain (csRRM2) improves components of Brassica napus yield by regulating cell size

With 4 figures and 1 table Abstract Oilseed rape (Brassica napus L.) is the second most important oilseed crop in the world, and greater production of rape oil is required to satisfy the growing demand for it. We previously found that the cell size and yield of rice (Oryza sativa) and cotton can be increased by over-expression of the RNA-binding domains (RRMs) of the flowering control locus A (FCA) protein. We also found that B. napus FCA-RRM2 shares a high level of sequence similarity with the RRM2 domains of other plants. We isolated B. napus FCA-RRM2 from variety No.1 ‘Nannongyou’ of Brassica napus. Transformation experiments demonstrated that over-expression of B. napus FCA-RRM2 increases plant size, organ size, cell size, plant productivity and oil content in transgenic rape plants by down-regulating the cell-cycle-related gene cyclin-B2-1, a known activator of cyclin-dependent kinase 1 at the G2/M boundary. These results provide a practical approach for the genetic improvement of B. napus and possibly provide a model for investigating cell size regulation.