黄腐酸处理对塔罗科血橙成熟过程中花色苷和糖酸积累的影响

Effects of preharvest application of fulvic acid on anthocyanin,sugar and organic acid accumulation in maturing Tarocco blood oranges

为探究血橙增糖促色的方法,该研究以塔罗科血橙为试材,于转色期后(花后230 d)叶面喷施1 g/L黄腐酸(fulvic acid,FA),运用高效液相色谱和实时荧光定量PCR等技术,测定塔罗科血橙成熟过程中花色苷和糖酸含量的变化及相关代谢基因表达丰度。结果表明,叶面喷施FA可促进血橙果肉着色,显著增加血橙花色苷以及总糖、果糖、葡萄糖、蔗糖的含量。花后324 d,FA组花色苷含量为48.92 mg/L,比对照组提高了153.7%。FA处理后血橙花色苷代谢基因4CL、CHS、DFR、ANS、UFGT、GST表达量显著上调。花后324 d,FA组总糖、果糖、葡萄糖、蔗糖含量分别为75.33、20.87、20.22、33.84 mg/g,比对照组分别提高了10.2%、15.1%、14.5%、6.7%。FA处理后血橙糖代谢基因AI表达量显著上调。而FA处理对血橙成熟过程中有机酸含量的影响不显著。FA处理后血橙酸代谢基因CS、AC、IDH调控柠檬酸积累的作用不大。综合分析认为,转色期后叶面喷施FA激活了4CL、CHS、DFR、ANS、UFGT、GST、AI表达,促进血橙增糖着色,改善血橙品质。

The accumulation of anthocyanin in blood oranges depends on a large diurnal temperature difference.At present,blood oranges grown in tropical/subtropical climates are generally not colored well,which limits the geographical cultivation of blood oranges.And the low sugar-acid ratio of blood oranges also reduces their flavor.To explore the approaches to improve the accumulation of sugar and anthocyanin in maturing blood oranges,Tarocco blood oranges(230 days after flowering,230 DAF)were treated with 1 g/L fulvic acid(FA),and then high-performance liquid chromatography(HPLC)was used to test the content of sugar and organic acid in Tarocco blood oranges at different maturity stages.The expression of genes involved in the related metabolic pathways was tested by quantitative real-time PCR(qRT-PCR).The results showed that preharvest application of fulvic acid could promote pulp coloring and significantly increase the content of anthocyanin,total sugar,fructose,glucose,sucrose in blood oranges.At 324 DAF,the anthocyanin content of FA treated group was 48.92 mg/L,increased by 153.7%compared to the CK group.After FA treatment,the expressions of 4CL,CHS,DFR,ANS,UFGT,GST were significantly up-regulated.Meanwhile,the total sugar,fructose,glucose,and sucrose content of FA treated group were 75.33,20.87,20.22,33.84 mg/g respectively,which increased by 10.2%,15.1%,14.5%,6.7%respectively compared to the CK group.Using FA treatment,the expression of AI was significantly up-regulated.However,FA treatment had no significant effect on the content of organic acid in maturing blood oranges.Moreover,the CS,AC,IDH had little effect on the accumulation of citric acid.These results suggested that preharvest application of fulvic acid after the veraison stage could activate the expressions of 4CL,CHS,DFR,ANS,UFGT,GST,AI,and promote sugar accumulation and fruit coloring in maturing blood oranges,and finally improves the fruit quality of blood oranges.