Find in Library

Fruit shape, an important agronomic trait of cucumber (<i>Cucumis sativus</i> L.), is tightly controlled by a series of genes such as <i>CsSUN</i>, a homologue of <i>SlSUN</i> that is responsible for the tomato (<i>Solanum lycopersicum</i>) fruit shape via the modulation of cell division. However, the direct genetic evidence about the <i>CsSUN</i>-mediated regulation of fruit shape is still scarce, limiting our mechanistic understanding of the biological functions of <i>CsSUN</i>. Here, we introduced <i>CsSUN</i> into the round-fruited tomato inbred line ‘SN1′ (wild type, WT) via the <i>Agrobacterium tumefaciens</i>-mediated method. The high and constitutive expression of <i>CsSUN</i> was revealed by real-time PCR in all the tested tissues of the transgenic plants, especially in the fruits and ovaries. Phenotypic analyses showed that the ectopic expression of <i>CsSUN</i> increased fruit length while it decreased fruit diameter, thus leading to the enhanced fruit shape index in the transgenic tomato lines relative to the WT. Additionally, the reduction in the seed size and seed-setting rate and the stimulation of seed germination were observed in the <i>CsSUN</i>-expressed tomato. A histological survey demonstrated that the elongated fruits were mainly derived from the significant increasing of the longitudinal cell number, which compensated for the negative effects of decreased cell area in the central columellae. These observations are different from action mode of <i>SlSUN</i>, thus shedding new insights into the <i>SUN</i>-mediated regulation of fruit shape.