地面覆膜提升椪柑果实品质的效果和可能机制探究

Effects of Film Mulching on Improving Fruit Quality of Ponkan and Possible Mechanisms

以椪柑(Citrusreticulata)‘鄂柑一号’为材料,探究地面覆膜对椪柑果实糖、酸含量和果皮色泽的影响,同时研究其可能的分子机制。结果表明:地面覆膜能显著提高椪柑果实可溶性固形物含量,蔗糖含量升高最为突出;覆膜处理使椪柑果实转色更快,成熟后果皮更红;然而覆膜对果实可滴定酸和柠檬酸含量影响不大。通过宽皮橘基因组分析,鉴定了6个蔗糖合酶基因(CrSUS1~CrSUS6)和5个蔗糖磷酸合成酶基因(CrSPS1~CrSPS4a/b)。基因表达分析发现,覆膜处理上调了多个CrSUS和CrSPS表达量。酶活性分析表明,覆膜处理增加了合成方向SUS酶活性,却降低了分解方向SUS酶活性。综上所述,地面覆膜能诱导椪柑果实SUS基因和SPS基因表达,促进了可溶性糖的合成,使果实糖分含量增加;此外,地面覆膜提高了果实固酸比,促进果实转色,因而在提升柑橘果实品质上有明显的效果。

In the current study the effects of film mulching above the soil on sugar and acid content and peel color of Citrus reticulata‘Egan 1’fruit and the possible molecular mechanisms were investigated.The results showed that film mulching could significantly increase the content of total soluble solids in the fruits,with the most prominent increase being detected in sucrose content.Film mulching promoted coloring of Ponkan fruits at an earlier stage,leading to more reddish peel at ripening.However,the contents of titratable acid and citric acid were not dramatically altered by film mulching.Six sucrose synthetase genes(CrSUS1–CrSUS6)and five sucrose phosphate synthetase genes(CrSPS1–CrSPS4a/b)were identified by analyzing the released genome of C.reticulata.Gene expression analysis showed that film mulching significantly up-regulated some of the CrSUS and Cr SPS genes.In addition,film mulching increased activity of the SUS enzyme involved in sucrose synthesis,but decreased the one associated with sucrose decomposition.In conclusion,film mulching enhanced the synthesis of soluble sugars and increased the content of sugars by inducing the expression of SUS and SPS genes in Ponkan fruits.Meanwhile,film mulching effectively elevated the ratio of total soluble solids/titratable acid,leading to better flavor,and stimulated fruit coloring,which demonstrated that it has an obviously positive effect on improving fruit quality.