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Department of Horticulture and Crop Science


Qi Mu's Masters Exit Seminar

Jul 13, 2015, 1:00pm - 2:00pm

Qi Mu's Masters Exit Seminar

Advisor: Dr. Esther van der Knaap

SAC Committee member: Dr. Eric Stockinger, Dr. Leah McHale

Title: The cloning and cellular basis of a novel fruit weight gene: Cell Size Regulator (FW11.3/CSR)

Abstract: Domestication and selective breeding of the tomato (Solanum lycopersicum) has produced an extremely large amount of diversity in fruit size and shape. Tomato fruit size is an important agronomic trait for commercial production as well as consumer preference. Fruit size, measured by weight, is determined by cell number and cell size, resulting from cell division and cell expansion, respectively. Of the 28 loci controlling tomato fruit weight, 2 have been cloned: FW2.2/CNR and FW3.2/SlKLUH. These loci were identified as contributing to the regulation of cell number via two different mechanisms, which ultimately led to fruit size alteration. A novel fruit weight locus fruit weight 11.3 (fw11.3) was cloned and the likely cellular basis for fruit enlargement was identified in this study. The fw11.3 locus was fine-mapped to a 13kb region on chromosome 11. DNA polymophrism analysis, association analysis and transgenic complementation tests demonstrated that Solyc11g71940 underlies fw11.3. The deletion leading to a 194 amino-acid truncation at the C-terminal was the most likely cause of fruit enlargement. Gene expression analysis revealed a dynamic regulation of Solyc11g71940 especially in the later stage of fruit development. Cell size and ploidy changes were observed in the fruit pericarp tissue of fw11.3 near isogenic lines (NILs), indicating a novel function of cell size regulation leading to fruit enlargement. Thus, we propose to rename FW11.3cell size regulator (CSR). Importantly, the ploidy analysis provided in this study linked endoreduplication to an increase in cell size and ultimately to fruit enlargement, this is pivotal to understanding the mechanism for fruit enlargement during crop domestication. Phylogenic analysis revealed a unique expansion of CSR in the Solanaceae family with three additional paralogs. Few pleiotropic phenotypic differences were observed, except for blossom-end rot, where a significantly higher incidence rate was found to be associated with CSR.

Monday July 13th 1:00-2:00 PM
Williams 123 (Wooster) video-linked to
Kottman 333D (Columbus)