【作者】 陈晨；

【导师】 熊爱生； 曾晓萍；

【作者基本信息】 南京农业大学 ， 园艺学（专业学位）， 2023， 硕士

【摘要】 芹菜（Apium graveolens L.）为伞形科（Apiaceae）芹属（Apium）植物,以叶片及叶柄为主要产品器官。叶绿素的生物合成及降解受相关基因表达水平的影响,涉及一系列复杂的酶促反应。叶绿素含量和叶绿素a/b比值是影响芹菜光合作用和品质形成的关键因素。油菜素甾醇类化合物（brassinosteroids,BRs）是一类微量高效的植物生长调节物质,可通过影响植物光合作用提高其叶绿素含量,改善作物生长发育状况及营养品质,2,4-表油菜素内酯（2,4-epibrassinolide,2,4-EBL）是其常见的生物活性较高的人工合成类似物。目前,外源2,4-EBL处理影响芹菜光合作用和品质形成的研究较少。本研究以‘宁芹一号’品种芹菜为试验材料,设置1.04×10^-6mol·L^-1和1.67×10^-6mol·L^-1两个2,4-EBL处理浓度,对45 DAS（days after sowing,播种后天数）的芹菜植株进行喷施处理,共计3次（第一阶段:45～52 DAS;第二阶段:52～59 DAS;第三阶段:59～66 DAS）。处理一周后,对芹菜进行取样,测定对照组及处理组芹菜叶片和叶柄主要农艺性状、营养品质指标、光合特性、叶绿素含量及相关基因表达水平。主要结果如下:1、2,4-EBL处理能影响芹菜农艺性状指标,促进芹菜生长。与对照组相比,第一阶段（45～52 DAS）1.04×10^-6mol·L^-1的2,4-EBL处理后,芹菜单株质量、叶柄长和叶柄数均显著增加。第二、三阶段（52～66 DAS）1.67×10^-6mol·L^-1的2,4-EBL处理后,芹菜单株质量、叶片长宽、叶柄粗及植株高度增加,叶柄输导组织发育受到促进。2、2,4-EBL处理能影响芹菜营养物质的积累,提高芹菜品质。第一阶段（45～52DAS）,外源2,4-EBL处理促进了芹菜叶柄木质素及叶片抗坏血酸的积累。第二阶段（52～59 DAS）,2,4-EBL处理后木质素及抗坏血酸在芹菜叶片及叶柄中的积累显著提升。第三阶段（59～66 DAS）2,4-EBL处理显著促进木质素和抗坏血酸在芹菜叶片及叶柄中的积累,叶片中类胡萝卜素（β-胡萝卜素和叶黄素）和叶柄中类黄酮（芹菜素和木犀草素）的含量提高。3、2,4-EBL处理能调控芹菜叶绿素代谢相关基因的表达,提高叶绿素含量和光合作用效率。叶绿素含量及比例与叶绿素合成相关基因Ag HEML和Ag CHLG、叶绿素循环再生相关基因Ag CLH及叶绿素降解相关基因Ag PPH相关性较强。第一阶段（45～52 DAS）,外源2,4-EBL处理促进了芹菜叶柄叶绿素b的积累。实时荧光定量结果表明,叶绿素合成相关基因Ag CHLG和Ag CAO及叶绿素循环再生途径基因Ag CLH的转录水平上调。第二阶段（52～59 DAS）,芹菜叶柄叶绿素的积累下降,叶绿素循环再生途径基因Ag CLH和降解途径相关基因Ag NYC表达上调;叶片光合作用受到促进。第三阶段（59～66 DAS）,2,4-EBL处理促进了芹菜光合作用及叶绿素积累,叶绿素b含量上调更为明显。表达分析结果表明,芹菜叶绿素合成基因Ag CHLG和循环再生途径基因Ag CLH的表达被诱导,叶绿素降解途径相关基因Ag NYC和Ag PPH表达水平下降。更多还原

【Abstract】 Celery（Apium graveolens L.）is a plant belonging to Apium of Apiaceae.Its leaf blades and petioles are the main production organs.The biosynthesis and degradation of chlorophyll involve a series of complex enzymatic reactions,which are influenced by the expression levels of related genes.Chlorophyll content and appropriate chlorophyll a/b ratio were the key factors affecting photosynthesis and quality formation of celery.Brassinosteroids（BRs）is a kind of highly efficient plant growth regulatory substances,which can increase plant chlorophyll content,improve crop growth,development status and nutritional quality by affecting plant photosynthesis.2,4-epibrassinolide（2,4-EBL）as a kind of common synthetic analogue of brassinosteroids with high biological activity,there are few studies on the effects of exogenous 2,4-EBL treatment on photosynthesis and quality formation of celery at present.In this study,‘Ningqin No.1’celery is used as the experimental material.Two 2,4-EBL treatment concentrations of 1.04×10^-6mol·L^-1and 1.67×10^-6mol·L^-1are set to apply spraying treatment to 45 DAS（days after sowing）celery plants,three times in total（The first stage:45～52 DAS;the second stage:52～59 DAS;the third stage:59～66 DAS）.After a week of processing,sample the celery,agronomic traits,nutritional quality indexes,photosynthetic characteristics,chlorophyll content and the expression levels of related genes in celery leaf blades and petioles of control group and treatment group were determined.The main results are as follows:1,2,4-EBL treatment can improve the agronomic traits of celery and promote the growth of celery.Compared with the control group,the single plant weight,petiole length and petiole number of celery were significantly increased after 2,4-EBL treatment of 1.04×10^-6mol·L^-1in the first stage（45～52 DAS）.During the second and third stages（52～66DAS）,1.67×10^-6mol·L^-1of 2,4-EBL treatment increased the weight of single plant,leaf length and width,petiole thickness and single plant height,promoted the development of petiole transport tissue of celery.2,2,4-EBL treatment can affect the accumulation of celery nutrients and improve the quality of celery.In the first stage（45～52 DAS）,exogenous 2,4-EBL treatment promoted the accumulation of lignin in celery petioles and ascorbic acid in celery leaf blades.In the second stage（52～59 DAS）,2,4-EBL treatment significantly promoted the accumulation of lignin and ascorbic acid in celery leaf blades and petioles.In the third stage（59～66 DAS）,2,4-EBL treatment significantly promoted the accumulation of lignin and ascorbic acid in celery leaf blades and petioles,as well as the accumulation of carotenoids（β-carotene and lutein）in leaf blades and flavonoids（apigenin and luteolin）in petioles.3,2,4-EBL treatment can regulate the expression of chlorophyll-related genes in celery,improve chlorophyll content and photosynthetic efficiency.The content and proportion of chlorophyll were strongly correlated with the genes related to chlorophyll synthesis Ag HEML and Ag CHLG,the genes related to chlorophyll recycling and regeneration Ag CLH and the genes related to chlorophyll degradation Ag PPH.In the first stage（45～52DAS）,exogenous 2,4-EBL treatment promoted the accumulation of chlorophyll b in celery petioles.Real-time quantitative PCR results showed that the transcription levels of chlorophyll synthesis genes Ag CHLG,Ag CAO and recycling pathway gene Ag CLH were up-regulated.During the second stages（52～59 DAS）,the accumulation of chlorophyll in celery petioles was inhibited,the expression of chlorophyll cycle regeneration pathway gene Ag CLH and degradation pathway related gene Ag NYC were up-regulated;and the photosynthesis of leaf blades was promoted.In the third stage（59～66 DAS）,2,4-EBL treatment promoted photosynthesis and chlorophyll accumulation in celery,and the up-regulation of chlorophyll b content was more obvious.The expressions of chlorophyll synthesis gene Ag CHLG and recycling pathway gene Ag CLH were induced,while the expression levels of chlorophyll degradation pathway related genes Ag NYC and Ag PPH were decreased.更多还原