摘要
【目的】环境破坏将引起农作物增强UV-B辐射危害,在低纬度热带地区将可能引起杧果(Mangifera indica L.)减产和果实品质变劣,探究杧果果实抗氧化酶系统对增强UV-B辐射的响应模式问题对杧果品质提升具有重要意义。【方法】以台农一号杧果果实为试验材料,人工模拟96 kJ×m-2·d-1的增强UV-B辐射处理,通过检测果肉活性氧含量、氧化应激指标、果实品质和抗氧化酶活性变化,基于转录组分析,探究杧果果实抗氧化酶系统响应增强UV-B辐射处理的初步分子机制。【结果】处理组果实变小,损伤外观品质;处理组果肉比对照早熟,可溶性糖含量显著升高,可滴定酸含量显著下降,糖酸比显著升高;处理组果肉活性氧自由基(ROS)、过氧化氢(H2O2)、丙二醛(MDA)含量和相对电导率(RC)在果实迅速膨大期高于对照,明显产生了活性氧损伤;处理组超氧化物歧化酶(SOD)和过氧化物酶(POD)活性在果实迅速膨大期显著强于对照;在果实采收期,处理组果肉RC和H2O2含量显著高于对照,果肉SOD活性和ROS含量均显著低于对照;在花后50 d,处理组果肉木质素合成通路中的基因4CL、HCT和COMT和部分编码POD基因家族成员呈上调表达趋势,经实时荧光定量PCR试验筛选出的高表达差异POD基因家族成员LOC123195912是响应增强UV-B胁迫的关键基因。【结论】增强UV-B辐射处理在果实采收期阻碍了果实生长,改善了果实内在品质;增强UV-B辐射处理通过诱导台农一号杧果果肉上调表达木质素合成通路中POD基因,进而增强清除ROS和耗散增强UV-B辐射胁迫的能力,从而抵御增强UV-B辐射胁迫。
【Objective】Environmental damage causes an increase in UV-B radiation content,posing a threat to crops.According to the research conducted by the experimental group,it was found that under artificial simulation of enhanced UV-B radiation,the fruit trees of Tainong No.1 showed a decrease in yield and deterioration in fruit quality.Our previous research has shown that enhancing UV-B radiation leads to a significant increase in reactive oxygen species(ROS)in fruits,causing oxidative stress damage and resulting in a decrease in fruit quality.In addition,the response of antioxidant enzymes to enhanced UV-B radiation has been widely reported.Therefore,the purpose of this study is to investigate the effect of enhanced UV-B radiation on the quality of mango fruit,and to elucidate the gene expression and response patterns of antioxidant enzymes in mango fruit under UV-B stress.【Methods】Using the Tainong No.1 mango tree as the experimental material,ten 16-year-old robust mango trees with a high-yield were selected,five plants in the treatment group were supplemented with 96 kJ·m^(2)·d^(-1)UV-B lamp irradiation under natural light,while five plants in the control group received natural light irradiation.Enhanced UV-B radiation treatment began 30 days after flowering and continued until fruit harvesting.During this period,at 10-day intervals,the changes in fruit size were observed and fruit pulp was extracted for measuring physiological indicators[ROS,hydrogen peroxide(H_(2)O_(2)),malondialdehyde(MDA)content,and relative conductivity(RC)],fruit quality(soluble sugar,titratable acid,and sugar/acid ratio)and changes in the activity of antioxidant enzyme systems[superoxide dismutase(SOD),peroxidase(POD),and catalase(CAT)].RNA was extracted from fruit pulp for transcriptome sequencing and data analysis,and significantly differentially expressed genes(DEGs)were validated using real-time fluorescence quantitative PCR.【Results】Under enhanced UV-B radiation,the fruit expansion rate was reduced compared with that of the control group,and the fruit size was smaller,which damaged the appearance quality of the fruit.However,at harvest(91 d after flowering),soluble sugar content in the treated group was significantly increased,while the titratable acid content significantly decreased and the sugar to acid ratio significantly increased,resulting in a significant improvement in the main nutritional flavor quality of the fruit.The results indicate that enhancing UV-B radiation promotes early fruit ripening,thereby improving fruit flavor quality.The treatment also led to an increase in the accumulation of ROS in the fruit.At 40 and 91 days after flowering,the H_(2)O_(2) content in the treatment group was significantly higher than that in the control group;at 77 days after flowering,the content of ROS was significantly higher than that of the control group,but at 91 days after flowering,the treatment was significantly lower than the control,and the damage of ROS in the flesh was basically consistent with the changes in ROS content.The activities of SOD and POD enzymes in the treatment group were lower than those in the control group during the early stage of fruit growth,but when oxidative damage occurred in the treated fruit(50 days after flowering),their activity significantly increased.At harvest,the RC and H_(2)O_(2) content in the treated pulp were significantly higher than the control,while the SOD activity and ROS content were significantly lower than the control.Interestingly,CAT activity did not show significant changes throughout the experiment.The results indicate that H_(2)O_(2) might be the major ROS causing early ripening of fruit in the treatment group.They also proved that SOD and POD are important antioxidant enzymes in mango fruit to alleviate oxidative stress and respond to enhanced UV-B radiation.Based on the measured physiological data,transcriptome analysis was performed on samples at 50 days after flowering and 91 days after flowering,when the flesh of mango fruit showed significant oxidative stress.At least 40820438 clean reads were obtained from each sample,with an error rate of 0.01%,indicating high data quality.At 50 days after flowering,treatment and control groups had 804 DEGs,of which 669 genes were upregulated and 135 genes were downregulated by the UV-B treatment.At 91 days after flowering,there were 189 DEGs,of which 118 were upregulated and 71 were downregulated by the treatment.Through KOG enrichment analysis of the DEGs from two periods,it was found that enhanced UV-B radiation increased the expression of secondary metabolism related genes in mango flesh;KEGG enrichment analysis showed that the DEGs in both periods were mainly enriched in the two pathways of biosynthesis of secondary metabolites and phenylalanine biosynthesis.The genes related to the antioxidant enzyme,POD,were enriched in the lignin synthesis pathway of Phenylpropanoid biosynthesis(ko00940).At 50 days after flowering,compared with the control group,the treatment group had a total of 12 DEGs enriched in this pathway,including 7 PODs,2 HCTs,1 F5H,1 COMT and 14CL.Except for the downregulated LOC123227833(F5H)and LOC123194338(POD),all the other genes were upregulated.At 91 days after flowering treatment,the difference was small,with only downregulation of LOC123194338(POD)and upregulation of LOC123209447(4CL)and LOC123225298(POD).The highly differentially expressed POD family member LOC123195912,validated through real-time fluorescence quantitative PCR analysis,is a key gene responsive to enhanced UV-B stress.【Conclusion】Comprehensive analysis shows that enhanced UV-B radiation treatment hinders fruit growth and improves the intrinsic quality of fruit of Tainong No.1 mango.The treatment induced upregulation of POD genes in the lignin synthesis pathway in the pulp;it enhances the ability to clear ROS and dissipate UV-B radiation stress,thereby increasing the resistance to UV-B radiation stress.
作者
施绍璞
魏玲
高怡佳
姜辰煜
焦佳冰
周开兵
SHI Shaopu;WEI Ling;GAO Yijia;JIANG Chenyu;JIAO Jiabing;ZHOU Kaibing(Sanya Institute of Breeding and Multiplication,Hainan University,Sanya 572025,Hainan,China;Tropical Agriculture and Forestry College,Hainan University,Haikou 570228,Hainan,China)
出处
《果树学报》
北大核心
2025年第9期2097-2113,共17页
Journal of Fruit Science
基金
国家自然科学基金项目(32160677)
海南省自然科学基金项目(321RC465)。
关键词
杧果
增强UV-B辐射
活性氧
抗氧化酶
木质素
转录组
Mango
Enhanced UV-B radiation
Reactive oxygen species
Antioxidant enzyme
Lignin
Transcriptome
作者简介
施绍璞,在读硕士研究生,研究方向为热带果树生理与栽培。E-mail:ssp@hainanu.edu.cn;通信作者:周开兵,E-mail:zkb@hainanu.edu.cn。
