【作者】 李艳；

【导师】 杨振超；

【作者基本信息】 西北农林科技大学 ， 设施园艺学， 2023， 硕士

【摘要】 植物光形态调控是植物生长发育一个非常重要的基础研究领域,在植物育种、植物生产以及食品产业等多个领域中有重大应用前景。前期研究表明,暗前远红光(EOD-FR,End of Day Far red Light)可以调控植物下胚轴的伸长生长,且不存在喷洒激素对环境和植物带来的负面效应,但调控机理和机制还不是完全清楚。本研究采用EOD-FR处理的方法探究调控幼苗下胚轴伸长生长的机理,从处理的时间、剂量、激素含量等指标并结合转录组测序(RNA-seq)探究EOD-FR处理影响下胚轴伸长生长的机制。研究分两步走,第一步以两种砧木南瓜(金砧木、日本雪松)和一种非砧木南瓜(蜜本南瓜)为试验材料,通过分析0、1、2、4、6、8mmol/m~2·d剂量的EOD-FR对南瓜下胚轴生长、形态发育、叶绿素和内源激素含量的影响来研究EOD-FR调控南瓜形态的差异性,并筛选出最佳的EOD-FR处理剂量。第二步采用南瓜砧木品种‘金砧木’和前期筛选的最佳日处理剂量5 mmol/m~2·d,设置外源赤霉素(GA)、油菜素内酯(BR)以及GA合成抑制剂(PAC)、BR合成抑制剂(BRZ)搭配EOD-FR组成18个处理,观察南瓜下胚轴伸长生长和内源GA、BR含量的变化,并结合RNA-seq技术,检测GA和BR相关基因的变化,通过实时定量PCR(q RT-PCR)验证所选基因的表达,探究EOD-FR和外源GA、BR处理对南瓜下胚轴伸长生长的调控机理及相互作用关系,为光形态调控植物下胚轴生长提供技术和理论参考。研究主要结果如下:1.三种南瓜幼苗的下胚轴长度随着远红光剂量的增大而增加,其中‘金砧木’和‘日本雪松’幼苗下胚轴长度在EOD-FR剂量为0-4 mol/m~2·d时迅速增加,之后下胚轴长度增加趋势逐渐变缓,下胚轴长度在EOD-FR剂量为4 mol/m~2·d时与无EOD-FR处理的对照比较分别提高了70.4%、57.1%;而‘蜜本南瓜’幼苗的下胚轴长度在EOD-FR剂量为0-2 mol/m~2·d时迅速增加,之后增加趋势逐渐变缓,与无EOD-FR处理的对照比较提高了21.3%;不同EOD-FR处理幼苗形态差异较大,但干物质量差异不显著;EOD-FR处理能显著提高南瓜下胚轴内源生长素(IAA)、油菜素内酯(BR)、赤霉素(GA)以及玉米素(ZT)的含量。2.EOD-FR可以显著提高内源GA和BR合成与信号转导基因的表达量,BRZ和PAC则会抑制GA和BR合成与信号转导基因的表达;在EOD-FR处理下,同时添加GA和BR的处理组,其下胚轴长度要显著高于添加BR或GA处理组的下胚轴长度,而且PAC和BRZ对下胚轴的抑制也具有叠加效应;BR可以缓解28.9%的PAC对下胚轴的抑制作用,GA也缓解了30.8%的BRZ对下胚轴的抑制作用,而且BRZ显著降低下胚轴内6.7%的GA含量,抑制GA的合成和信号转导相关基因的表达,PAC显著降低了下胚轴内20.9%的BR含量,也抑制了BR合成和信号转导相关基因的表达。综上所述,添加适宜剂量的EOD-FR可有效的调整幼苗的下胚轴伸长生长,而且不会影响幼苗的健壮程度,其调控机理是EOD-FR处理通过提高GA、BR相关基因表达进而增加内源激素的含量来调控下胚轴伸长生长。更多还原

【Abstract】 The regulation of plant photomorphology is a very important fundamental research field in plant growth and development,with significant application prospects in multiple fields such as plant breeding,plant production,and the food industry.Previous studies have shown that EOD-FR(End of Day Far red Light)can regulate the elongation and growth of plant hypocotyls,and there is no negative effect of spraying hormones on the environment and plants.However,the regulatory mechanism and mechanism are not fully understood.This study used the EOD-FR treatment method to explore the mechanism of regulating the elongation and growth of seedling hypocotyls.The mechanism of EOD-FR treatment affecting hypocotyl elongation and growth was explored through indicators such as treatment time,dose,hormone content,and transcriptome sequencing(RNA seq).The study is divided into two steps.The first step is to use two types of rootstock pumpkin(Jinanmu,Japanese cedar)and one type of non rootstock pumpkin(Mimoto pumpkin)as experimental materials.By analyzing the effects of 0,1,2,,4,6,8 doses of EOD-FR on the growth,morphological development,chlorophyll and endogenous hormone content of pumpkin hypocotyls,the differences in EOD-FR regulation of pumpkin morphology were studied,and the optimal EOD-FR treatment dose was selected.The second step is to use the pumpkin rootstock variety’Japanese cedar’and the optimal daily treatment dose of 5mmol/m~2·d selected in the previous stage.Exogenous gibberellin(GA),brassinolide(BR),GA synthesis inhibitor(PAC),BR synthesis inhibitor(BRZ),and EOD-FR were used to form 18 treatments.The elongation growth of pumpkin hypocotyls and changes in endogenous GA and BR content were observed,and RNA seq technology was used to detect changes in GA and BR related genes,Verify the expression of selected genes through real-time quantitative real-time PCR(q RT PCR),explore the regulatory mechanism and interaction relationship of EOD-FR and exogenous GA and BR treatments on the elongation and growth of pumpkin hypocotyls,and provide technical and theoretical references for the regulation of plant hypocotyl growth by photomorphology.The main results of the study are as follows:1.The hypocotyl length of three types of pumpkin seedlings increased with the increase of far-red light dose.Among them,the hypocotyl length of’Golden Rootstock’and’Japanese Cedar’seedlings rapidly increased when the EOD-FR dose was 0-4 mol/m~2·d,and then the trend of hypocotyl length increase gradually slowed down.The hypocotyl length increased by 70.4%and 57.1%compared to the control without EOD-FR treatment when the EOD-FR dose was 4 mol/m~2·d,respectively;The hypocotyl length of’Mimoto pumpkin’seedlings rapidly increased at an EOD-FR dose of 0-2 mol/m~2·d,and then the increasing trend gradually slowed down,increasing by 21.3%compared to the control without EOD-FR treatment;There were significant differences in seedling morphology among different EOD-FR treatments,but there was no significant difference in dry matter quality;EOD-FR treatment can significantly increase the content of endogenous auxin(IAA),brassinolide(BR),gibberellin(GA),and zeatin(ZT)in pumpkin hypocotyls.2.EOD-FR can significantly increase the expression levels of endogenous GA and BR synthesis and signal transduction genes;Under EOD-FR treatment,the hypocotyl length of the group treated with both GA and BR was significantly higher than that of the group treated with BR or GA,and the inhibition of hypocotyl by PAC and BRZ also had a synergistic effect;BR can alleviate the inhibitory effect of 28.9%PAC on the hypocotyl,while GA also alleviates the inhibitory effect of 30.8%BRZ on the hypocotyl.Moreover,BRZ significantly reduces the GA content in the hypocotyl by 6.7%,inhibiting the synthesis of GA and the expression of signal transduction related genes.PAC significantly reduces the BR content in the hypocotyl by 20.9%,and also inhibits the expression of BR synthesis and signal transduction related genes.In summary,adding an appropriate dose of EOD-FR can effectively regulate the elongation and growth of the hypocotyl of seedlings,without affecting the robustness of the seedlings.The regulatory mechanism is that EOD-FR treatment regulates the elongation and growth of the hypocotyl by increasing the expression of GA and BR related genes,thereby increasing the content of endogenous hormones.更多还原