| Quality improvement is an important goal of apple breeding, and texture is a key indicator of fruit quality. It is vital to study the related mechanism of differences in various fruit texture in order to provide guides for parent selection and combination in quality breeding. To find out the key factors leading to different texture of the two cultivars and provide a theoretical basis for apple texture improvement, ‘Qinguan’ and ‘Fuji’ were choosed as material, fruit firmness and crispness, metabolism of cell wall and starch, and microstructure of pulp cells were studied during fruit development, finally, internal association among them was analyzed. The main results are as follows:1. Firmness and crispness of both cultivars gradually reduced during fruit development. However, differences existed between the two cultivars. Higher crispness of ‘Fuji’ was noted compared to ‘Qinguan’ at the whole stages. While, larger reduction in firmness of ‘Fuji’ was observed, and significantly lower firmness of ‘Fuji’ was estimated compared to ‘Qinguan’ later than 115 days after flower.2. Higher growth rate and larger size of pulp cells for ‘Fuji’ were observed compared to ‘Qinguan’ during fruit development, which were consistent with the substantial decline in firmness of ‘Fuji’. It indicated that different cell microstructure was an important factor for various fruit firmness.3. Significantly lower content of CSP and cellulose of ‘Fuji’ was found compared to ‘Qinguan’ under the combined regulation of genes β-Xyl, β-Gal, XET1 and XET2 during fruit development, which was significantly positively related to lower firmness.4. Starch content of both cultivars gradually reduced during fruit development. Flatter decline curve for ‘Qinguan’ was observed compared to ‘Fuji’, but a similar level in starch content was detected between the two cultivars when harvested, indicading that starch content was not an vital factor for fruit firmness. |
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