刺梨果实发育过程中糖和黄酮的积累及其与光照强度变化的相关性

【目的】研究不同光照强度对刺梨（Rosa roxburghii Tratt.）果实发育过程中糖和总黄酮的积累规律及其对光照强度变化的生理关联性,为刺梨果实的品质调控提供科学依据。【方法】以4年生的‘贵农5号’刺梨结果树为材料,以自然光照强度为对照,设置光照强度减弱20%、40%、60%的3个处理（分别用R0（CK）、R20、R40、R60表示）,分析测定不同发育时期刺梨果实中可溶性糖和总黄酮的积累量、相关合成代谢酶活性及其与光照强度变化的相互关系。【结果】在刺梨果实生长发育过程中,糖和总黄酮类物质不断积累,但不同发育时期的积累量有明显差异。在果实缓慢生长期之后,果实中的糖分开始快速积累,到成熟期可溶性总糖和蔗糖的积累量达到最高,其中蔗糖的积累量占可溶性总糖的36.97%。刺梨果实中葡萄糖和果糖的积累量至快速膨大期达到最大,但仅占果实成熟期可溶性总糖最大积累量的10.50%和18.18%。刺梨果实属于蔗糖积累型。刺梨果实中的总黄酮从幼果期开始就快速积累,一直持续到果实快速膨大期,之后总黄酮的积累量增加不明显。刺梨果实发育过程中,不同光照强度下的果实中糖和总黄酮的积累量差异显著,光照强度减弱不利于果实中糖和总黄酮的积累。蔗糖合成酶（SS）、蔗糖磷酸合成酶（SPS）、转化酶（IVR）和丙氨酸解氨酶（PAL）、肉桂酸-4-羟基化酶（C4H）、4-香豆酸辅酶A连接酶（4CL）、查尔酮合成酶（CHS）分别是影响果实中糖和黄酮类物质合成代谢的关键酶,光照强度变化与刺梨果实中糖、总黄酮的积累量以及相关合成代谢酶的活性变化密切关联。光照强度减弱会明显抑制SS、SPS、IVR、PAL、C4H、4CL、CHS的活性。在刺梨果实整个发育过程中,SS和SPS对光照强度减弱的反应敏感。刺梨果实中糖与总黄酮的积累量呈极显著正相关,果实中糖和总黄酮的积累量以及SS、SPS、IVR、PAL、C4H、4CL、CHS的活性均与光照强度变化呈显著或极显著正相关。【结论】刺梨果实为蔗糖积累型,果实缓慢生长期之后,果实中的糖分开始快速积累,果实中总黄酮的积累量从幼果期开始迅速增长,一直持续到快速膨大期。光照强度减弱不利于刺梨果实中糖和黄酮类物质的积累。生产中可以通过改善光照条件,增加刺梨果实中糖和黄酮类物质的含量,提高刺梨果实的品质。

Accumulation of Sugar and Flavonoids as Well as Their Association with Changes of Light Intensity During Fruit Development of Rosa roxburghii

【Objective】The accumulation of sugar and total flavonoids and their association with changes of light intensity during fruits development of Rosa roxburghii Tratt. were studied, so as to provide a scientific basis for the fruit quality control of Rosa roxburghii. 【Method】 Four-year-old ‘Guinong 5’ fruit-bearing trees of Rosa roxburghii was used as the material in the experiment, the natural light intensity was used as control (R0, CK), and three treatments were set up with the light intensity reduced by 20% (R20), 40% (R40) and 60% (R60), respectively. The accumulations of soluble sugar and total flavonoids as well as activities of related anabolic enzymes in fruits were analyzed, and the relationship between them and light intensity was determined. 【Result】Sugar and total flavonoids were accumulated continuously during the growth and development of Rosa roxburghii fruit, but their accumulation of different development periods had significant differences. The sugar in fruits began to accumulate rapidly after the slow growth stage, and the accumulation of total soluble sugar and sucrose reached the highest at maturity stage, in which the accumulation of sucrose accounted for 36.97% of the total soluble sugar. The accumulation of glucose and fructose in the rapid expansion period was the largest, but only accounted for 10.50% and 18.18% of the maximum accumulation of total soluble sugar at fruit maturity stage, respectively. Rosa roxburghii fruit was sucrose accumulation type. The total flavonoids in fruits were rapidly accumulated from young fruit stage to rapid fruit expansion stage, and then the accumulation of total flavonoids did not increase significantly. During the development of Rosa roxburghii fruit, the accumulation of sugar and total flavonoids under different light intensities was significantly different, while the decrease of light intensity was not conducive to the accumulation of sugar and total flavonoids in fruits. Sucrose synthase (SS), sucrose phosphate synthase (SPS), invertase (IVR) were the key enzymes affecting the metabolism of sugar in fruit. Alanine ammonia lyase (PAL), cinnamic acid-4-hydroxylase (C4H), 4-coumaric acid coenzyme A ligase (4CL) and chalcone synthase (CHS) were the key enzymes affecting the metabolism of flavonoids in fruit. The changes of light intensity were closely related to the accumulation of sugar, total flavonoids and the activities of related anabolic enzymes in fruits, while the activities of SS, SPS, IVR, PAL, C4H, 4CL and CHS were significantly inhibited by the decrease of light intensity. SS and SPS were sensitive to the decrease of light intensity during the whole fruit development of Rosa roxburghii. There was a significant positive correlation between sugar and total flavonoids accumulation in fruits, while the accumulation of sugar and total flavonoids and the activities of SS, SPS, IVR, PAL, C4H, 4CL and CHS were significantly or extremely significantly positively correlated with the changes of light intensity. 【Conclusion】Rosa roxburghii fruit were sucrose accumulation type, and the sugar in fruits began to accumulate rapidly after the slow growth stage, while the total flavonoids in fruits were rapidly accumulated from young fruit stage to rapid fruit expansion stage. The decrease of light intensity was not conducive to the accumulation of sugar and flavonoids in fruits. The contents of sugar and flavonoids in fruits could be increased by improving light conditions in production, which was conducive to improving the quality of Rosa roxburghii fruit.