【作者】 刘敏；

【导师】 杜国栋；

【作者基本信息】 沈阳农业大学 ， 果树学， 2024， 硕士

【摘要】 近年来,国内果树产业发展迅猛。其中,梨的栽培面积和产量扩展较为明显。梨成为仅次于苹果和柑橘的第三大水果作物。然而,随着梨产业的快速发展,因梨园土壤出现盐碱化问题而导致梨树叶片黄化、干枯等现象时有发生。此外,在生产及销售过程中产生的残次果浪费问题及环境污染问题也日益显现。因此,本研究以第一机械林场梨果园、科尔沁沙地南麓梨果园和沈阳农业大学试验基地为例。选取盐碱土栽培的野生秋子梨苗为研究对象。用梨残次果制备的发酵液与硫酸亚铁溶液进行螯合,矫正盐碱地梨树叶片缺铁黄化、萎蔫、干枯等现象。利用生理生化和分子技术,探究螯合液矫正盐碱地梨树叶片黄化的成因及调控机制,为残次果高效利用提供借鉴。以下是本研究取得的主要结果:1.通过对第一机械林场梨果园、科尔沁沙地南麓梨果园和沈阳农业大学试验基地的土壤状况以及梨树叶片的抗氧化酶、叶绿素等指标进行测定。发现第一机械林场梨果园和科尔沁沙地南麓梨果园的土壤pH和碳酸氢根含量明显高于沈阳农业大学试验基地。此外,第一机械林场梨果园、科尔沁沙地南麓梨果园梨树叶片的抗氧化酶活性显著高于沈阳农业大学试验基地,而叶绿素和有效铁含量却低于沈阳农业大学试验基地的梨树叶片叶绿素和有效铁含量。梨树叶片丙二醛及超氧阴离子含量和抗氧化酶活性也增强。2.通过将果园中收集的落果与鸟害果进行发酵60 d后,添加1%的硫酸亚铁溶液进行螯合,制备残次果螯合液。研究发现,残次果发酵液与1%硫酸亚铁溶液的最佳螯合体积比为3∶1、螯合液pH=6、螯合温度25℃、螯合时间为90 min。土壤施用残次果螯合液600倍稀释液,能有效提高叶片叶绿素,有效铁含量和抗氧化酶活性,降低丙二醛和超氧阴离子含量,缓解盐碱胁迫作用效果较好。3.对残次果螯合液600倍稀释液处理的野生秋子梨幼苗叶片进行转录组测序和分析,筛选出PuFSD2基因。其定位于叶绿体中,能够调节铁超氧化物歧化酶活性,具有清除叶绿体中活性氧的功能,是具有缓解黄化叶片的重要作用的基因。通过在转录组中筛选出与PuFSD2基因有结合位点的PuMYB21-like转录因子。通过基因表达分析和酵母单杂交试验等基因功能验证。研究发现,该基因通过提高叶绿体中铁超氧化物酶活性,减少活性氧在叶绿体中积累,使叶绿体功能正常运行。PuFSD2和PuMYB21-like基因在高pH、高碳酸氢根离子胁迫过程中起正调控作用。综上,PuFSD2探究螯合液矫正盐碱地梨树叶片黄化的成因及调控机制,为残次果高效利用提供借鉴。更多还原

【Abstract】 In recent years,the domestic fruit tree industry has developed rapidly,and pears have become the third largest fruit crop after apples and citrus.In 2020,China’s pear production reached 1.78×10~7t.With the increase of pear yield,the soil nutrients in pear orchards began to decline continuously,especially the salinization of pear orchard soil was the most serious.In addition,the residual fruit produced in the production and sales process is also one of the reasons that limit the development of the pear industry.Therefore,this study took the pear orchard of the first mechanical forest farm,the pear orchard at the southern foot of the Horqin Sandy Land and the experimental base of Shenyang Agricultural University as examples.Wild autumn pear seedlings cultivated in saline-alkali soil were selected as the research object.The fermentation broth prepared from pear residue fruit was chelated with ferrous sulfate solution to correct the phenomenon of iron deficiency yellowing,wilting and drying up of pear leaves in saline-alkali land.Through physiology,biochemistry and molecular techniques,the relationship between soil and pear tree growth and development in saline-alkali pear orchard was systematically studied.The aim of this study was to explore the alleviating effect of residual fruit chelated solution on the growth of pear trees under saline-alkali stress.The following are the key results of this study:the soil conditions,antioxidant enzymes,chlorophyll and other indicators of pear leaves were measured in pear orchards on the west side of Nenjiang Plain,pear orchards at the south foot of Horqin Sandy Land and experimental base of Shenyang Agricultural University.1.The soil conditions of the pear orchard of the first mechanical forest farm,the pear orchard at the southern foot of the Horqin Sandy Land and the experimental base of Shenyang Agricultural University,as well as the antioxidant enzymes and chlorophyll of pear leaves,were measured.It was found that the soil pH and bicarbonate content of the pear orchard of the first mechanical forest farm and the pear orchard at the southern foot of the Horqin Sandy Land were significantly higher than those of the experimental base of Shenyang Agricultural University.In addition,the antioxidant enzyme activities of pear leave in the pear orchard of the First Mechanical Forest Farm and the pear orchard at the southern foot of the Horqin Sandy Land were significantly higher than those in the experimental base of Shenyang Agricultural University,while the contents of chlorophyll and available iron decreased.These results indicate that under the conditions of high pH and high bicarbonate ions,pear trees exhibit stress characteristics,such as iron deficiency yellowing,chlorophyll content and available iron content decrease.At the same time,the contents of malondialdehyde and superoxide anion and antioxidant enzyme activities in pear leaves were enhanced.2.By fermenting the fallen fruit collected in the orchard with the bird infestation fruit,and adding ferrous sulfate solution to it for chelation,the residual fruit chelation solution was prepared.The optimal volume ratio of the fermentation broth to 1%ferrous sulfate solution was 3∶1,pH=6,chelation temperature 25°C,and chelation time 90 min.Soil application of600-fold dilution of residual fruit chelating solution can effectively increase leaf chlorophyll,available iron content and antioxidant enzyme activity,reduce malondialdehyde and superoxide anion content,and alleviate alkaline stress.3.The leaves of wild P.autumnus seedlings treated with 600-fold dilution of residual fruit chelation solution were sequenced and analyzed by transcriptome sequencing and analysis,and the PuFSD2 gene was screened.This gene is mapped in chloroplasts,regulates iron superoxide dismutase activity,has the function of scavenging reactive oxygen species in chloroplasts,and plays an important role in alleviating yellowing.The PuMYB21-like transcription factor with binding sites to the PuFSD2 gene was screened in the transcriptome.Gene function verification such as gene expression analysis and yeast single hybrid assay is performed.It was found that this gene can improve the normal function of chloroplasts by increasing the activity of iron superoxidase in chloroplasts,reducing the accumulation of reactive oxygen species in chloroplasts.It can effectively alleviate the phenomenon of leaf iron deficiency and green loss and yield decline caused by saline-alkali stress.PuFSD2 and PuMYB21-like genes play a positive regulatory role in the process of high pH and high bicarbonate ion stress.更多还原