生长调节剂及钙、硼肥对南果梨萼片脱落、果实品质及木质素代谢的影响

Effect of Growth Regulators, Ca and B Fertilizers on Calyx Abscission,Fruit Quality, and Lignin Metabolism in Nanguo Pear

南果梨果实萼片宿存率较高,宿萼果通常石细胞较多,口感差,严重影响果实品质。因此,研究不同外源物质对脱萼率、果实品质和木质素代谢的影响,对于实现南果梨果实品质的提升和优质高效栽培具有重要的意义。以南果梨为试材,于盛花期喷施不同浓度的GA3、PBO、PBO+钙硼溶液的混合制剂处理,对各处理果实的脱萼果率、可滴定酸、可溶性固形物、维生素C、花青苷及石细胞、木质素含量进行测定,采用液相-质谱法(LC-MS)检测果实中酚类物质含量,并选取部分木质素代谢相关基因进行表达水平分析。结果表明:50mg·L^-1GA3处理宿萼果率可达100%,且导致果实石细胞含量增加;单独使用PBO虽能大幅提高南果梨脱萼果率,降低有机酸含量,但对果实石细胞作用不显著;而PBO+钙硼合剂的处理不仅能有效提高脱萼率,显著增加可溶性固形物含量,同时可使石细胞含量减少12.2%,对果实品质有明显提升。与对照相比,PBO+钙硼合剂处理使南果梨木质素及其前体羟基肉桂酸类物质的含量显著降低,木质素合成相关基因(C4H、COMT和CAD)的表达水平也明显下调,抑制了木质素单体的合成,从而减少了石细胞的积累。因此,PBO+钙硼合剂处理可在提高脱萼率的同时,降低石细胞含量,有效提升南果梨果实品质。

The ratio of fruit with calyx in Nanguo pear is higher. This kind of fruit usually has many stone cells and poor taste, which seriously affects fruit quality. Therefore, it is of great significance to study the effects of different exogenous substances on the ratio of the fruit without calyx, fruit quality and stone cell content of pear in order to improve the fruit quality and realize high efficiency cultivation. Nanguo pear was used as experiment materials, and the effects of the growth regulators, Ca and B fertilizers on the fruit quality were studied by spraying the different concentrations of GA3, PBO, and a mixture of PBO plus elements of calcium and boron at full-bloom stage. The calyx shedding rate, titratable acid, soluble solids, vitamin C, anthocyanin, stone cells and lignin contents of each treatment were analyzed. In addition, phenolic metabolites were determined by liquid chromatography-mass spectrometry (LC-MS). Furthermore, the expression of monolignol biosynthetic genes was analyzed with quantitative PCR. The results showed that the percentage of calyx persistency fruit, stone cell content in fruit were all markedly increased under the spraying of 50 mg·L^-1 GA3. The ratio of the fruit without calyx increased, and the organic acid content in fruit decreased, but the change of stone cell content was not significant with the application of PBO. The treatment of PBO-calcium-boron mixture could not only increase the rate of calyx-shed fruit, but also reduce stone cell contents by 12.2%, increase the content of soluble solids, and improve the fruit quality. Compared with the control, the contents of lignin and hydroxycinnamic acids in fruit were significantly decreased after treated with PBO-calcium-boron mixture, and the expression level of lignin synthesis-related gene (C4H, COMT, CAD) was also down-regulated. The synthesis of lignin monomer was inhibited, thus the accumulation of stone cells was reduced. Therefore, PBO-calcium-boron mixture can not only increase the calyx shedding rate, but also reduce the content of stone cells and effectively improve the fruit quality.