光质在血橙果皮花色苷合成中的调控作用

【目的】探明光质在血橙果皮花色苷合成中的调控作用,为精确解答生产中血橙果面花色苷着色规律和研发血橙提质增效方法提供科学依据。【方法】对血橙果实进行遮光处理,采用可见光(390~780 nm)、紫外+可见光(300~780 nm)、长波紫外线(365 nm)和中波紫外线(311 nm)在果实转色期间照射,以不作照射的遮光果实为对照,动态测定各处理血橙果皮中总花色苷和可溶性糖含量,使用实时荧光定量PCR测定果皮中7个花色苷合成相关基因的动态表达情况。【结果】血橙转色期间,遮光条件下经对照、可见光和长波紫外线照射的果实,其果面均无花色苷着色;紫外+可见光和中波紫外线照射果实,其果面在照射46 d时均呈现花色苷着色,果皮花色苷含量分别为1.78和1.75 mg/kg,照射61 d时,果皮花色苷含量分别为8.78和6.15 mg/kg。试验期间,对照和各补光处理的血橙果皮中果糖和葡萄糖含量持续累积,尤其在紫外+可见光、长波紫外线和中波紫外线光质照射下,果皮果糖和葡萄糖含量明显高于可见光处理。转色期间,血橙果皮中7个花色苷合成相关基因(4CL、CHS、DFR、ANS、UFGT、GST和Ruby)在不同补光条件下的表达量均呈增长趋势,尤其在紫外+可见光和中波紫外线照射果实中,上述7个基因在各采样期的表达均明显高于同期其他处理,补光61 d时果皮中7个基因的表达量分别比同期其余处理至少高2.42和2.76倍、26.46和23.91倍、46.68和44.24倍、10.94和9.70倍、2.09和2.09倍、42.84和36.28倍、5.58和4.99倍。【结论】中波紫外线是诱导血橙果皮花色苷合成的真正光质,血橙转色过程中,其激发果皮中花色苷合成相关基因的大量表达,促进果糖、葡萄糖的快速积累,最终促成花色苷在果皮中的快速合成。

Regulatory function of light quality on anthocyanin synthesis in blood orange peel

【Objective】To explore the role of light quality in the regulation of anthocyanin biosynthesis in blood orangepeel,so as to provide scientific basis for uncovering the coloring regularity of anthocyanin in blood orange peel and developing the method of improving the blood orange fruit quality and production efficiency.【Method】Blood orange was treated with shading treatment. Visible light(VL,390-780 nm),partial UV and visible light(UV + VL,300-780 nm),long-wave ultraviolet(UVA,365 nm)and medium wave ultraviolet(UVB,311 nm)were used to irradiate the fruit during color-changing period. The fruits shaded without light irradiating treatment were used as the control group. The content of total anthocyanin and soluble sugar in blood orange peel of different treatment groups were determined dynamically,and the dynamic expressions of 7 genes related to anthocyanin synthesis were detected by real-time fluorescence quantitative PCR(qRT-PCR).【Result】In the color-changing period,the shaded blood orange peel,the control and the groups irradiated by VL or UVA did not showed purplish-red colorof anthocyanin under shading condition.After 46 days irradiation with UV+VL and UVB supplementary light,the fruit peel of two experimental groups showed the color of anthocyanin,and the contents of anthocyanin in the peel were 1.78 and 1.75 mg/kg,respectively. After 61 days irradiation,the contents of anthocyanin in peel were increased to 8.78 and 6.15 mg/kg,respectively. During the experiment,the fructose and glucose contents in the peel of blood orange were continuously accumulated,especially under the irradiation of UV+VL,UVA and UVB. The fructose and glucose contents of these three treatment groups were obviously higher than those of other treatment groups. The expressions of 7 genes(4CL,CHS,DFR,ANS,UFGT,GST and Ruby)involved in anthocyanin biosynthesis showed an increasing trend in all the treatment groups. Under UV+VL and UVB irradiation treatments,the expressions of these 7 genes in the peel were significantly higher than those of other treatment groups at each sampling stage.After 61 days of UV+VL and UVB supplementary irradiation,the expression of 4CL,CHS,DFR,ANS,UFGT,GST and Ruby in the peel were at least 2.42 and 2.76 times,26.46 and 23.91 times,46.68 and 44.24 times,10.94 and 9.70times,2.09 and 2.09 times,42.84 and 36.28 times,5.58 and 4.99 times higher than other treatment groups,respectively.【Conclusion】UVB is the light that can induce anthocyanin synthesis in blood orange peel. UVB enhances the expression of most genesrelated toanthocyanin biosynthetic,promotes the rapid accumulation of fructose and glucose,and finally induces the biosynthesis and accumulation of anthocyanins in the peel during blood orange ripening.