套袋对海沃德猕猴桃果实品质及叶绿素代谢的影响

Effect of bagging on fruit quality and chlorophyll metabolism of Hayward kiwifruit

【目的】探究套袋对海沃德猕猴桃果实品质、色泽及叶绿素代谢等指标的影响,为猕猴桃叶绿素代谢机理研究提供科学依据。【方法】于盛花期后30 d,以不套袋作为对照(CK),用外黄内黑单层袋、外黄内黑双层袋、白色单层袋、黄色条纹单层袋4种类型果袋对海沃德猕猴桃果实进行套袋处理,测定并分析不同处理猕猴桃果实外观品质(果实纵径、横径、侧径及单果质量)、内在品质(可溶性固形物含量、总酸含量、固酸比、果实硬度及干物质含量)、糖含量(果实蔗糖、果糖及葡萄糖含量)、果皮与果肉色泽变化、果实叶绿素含量及叶绿素代谢相关基因的表达情况。【结果】与对照相比,各套袋处理对海沃德猕猴桃果实纵径、横径、侧径、单果质量、可溶性固形物含量及干物质含量均无显著影响;除白色单层袋处理外,其余套袋处理果实总酸含量均有所下降,固酸比均有所上升。各套袋处理果实蔗糖含量均显著降低,最多较对照降低66.50%;除外黄内黑双层袋处理外,其余套袋处理果实果糖含量和葡萄糖含量均有所下降。外黄内黑单层袋和外黄内黑双层袋处理果皮a值、果肉a和h值均显著增加,果肉b、C^(*)、h^(*)值均显著降低;套袋处理果实叶绿素a及总叶绿素含量均显著降低,最大降幅分别为93.20%和91.60%。实时荧光定量PCR分析发现,套袋处理后果实叶绿素合成相关基因AdCAO表达丰度显著下调,AdGLUTR3表达丰度总体呈下调趋势;黄色条纹单层袋处理后叶绿素降解相关基因AdCBR1、AdPPH2表达丰度显著上调,AdCBR2、AdCBR3、AdPAO、AdSGR1、AdPPH1、AdPPH3表达丰度均有所上调。【结论】套袋处理对猕猴桃果实外观品质并无显著影响,但会改变果实糖组分所占比例;同时,果实叶绿素合成及降解相关基因的表达丰度发生改变,叶绿素含量降低,果肉颜色发生改变。

【Objective】The effects of bagging on fruit quality,color and chlorophyll metabolism of Hayward kiwifruit were explored to provide basis for the study of chlorophyll metabolism.【Method】Fruit bagging treatments were performed with four kinds of fruit bags including outer yellow and inner black single-layer bag,outer yellow and inner black double-layer bag,white single-layer bag and yellow stripes single-layer bag around 30 d after full-bloom flowering with no bagging as the control(CK).Fruit appearance quality(longitudinal diameter,transverse diameter,lateral diameter and weight),fruit inherent quality(soluble solid content,total acid content,SSC/TAC,fruit firmness and dry matter content),sugars content(sucrose,fructose and glucose),color changes of epicarp and flesh,chlorophyll concentration and expression patterns of chlorophyll-related genes were determined and analyzed.【Result】Compared with CK,different bagging treatments had no significant effects on the longitudinal diameter,transverse diameter,late-ral diameter,fruit weight,soluble solid content and dry matter content.Except white single-layer bag treatment,the total acid content decreased and solid-acid ratio increased in other treatments.The sucrose content of kiwifruit decreased significantly by bagging treatments with the most reduction of 66.50%.Except outer yellow and inner black double-layer bag,the fructose and glucose concentrations of fruit decreased in other bagging treatments.In treatments of outer yellow and inner black single-layer bag and outer yellow and inner black double-layer bag,a value of epicarp increased significantly,a and h values of flesh increased significantly,while b,C^(*) and h^(*) values of flesh decreased significantly.Meanwhile,chlorophyll a and total chlorophyll concentrations of flesh were decreased significantly by bagging treatments with the maximum reductions of 93.20%and 91.60%,respectively.Real-time quantitative PCR showed that the expression abundance of chlorophyll biosynthetic gene AdCAO was significantly down-regulated,and that of AdGULTR3 was down-regulated by bagging treatments.The expression abundances of chlorophyll degradation genes CBR1 and PPH2 were significantly up-regulated,and those of AdCBR2,AdCBR3,AdPAO,AdSGR1,AdPPH1 and AdPPH3 were up-regulated by yellow stripes single-layer bag treatment.【Conclusion】Fruit bagging treatments had no significant effects on the appearance quality of Hayward kiwifruit,but changed the proportions of fruit sugars.Meanwhile,the expression abundances of chlorophyll synthesis and degradation related genes were changed and chlorophyll contents were decreased,resulting in the change of fruit color.