大麦近等基因系苗期根系形态及叶片渗透调节物质对PEG胁迫的响应

摘要

[目的]研究大麦半矮秆基因uZu与抗旱性的关系,为大麦抗旱优质育种提供理论依据.[方法]以两套大麦株高近等基因系(3T、3D和15T、15D)为试验材料,采用营养液水培方式,以不同浓度的PEG6000模拟干旱胁迫,研究不同胁迫程度:对照(0)、轻度(5％)、中度(1 5％)和重度胁迫(25％)对大麦株高近等基因系幼苗株高、根冠比、根系形态及叶片渗透调节物质的影响.在幼苗长至四叶一心时取样,直尺测定株高;采用烘干称重法获得根系生物量和地上部生物量,二者比值乘以100％得到根冠比;利用根系扫描仪对样根进行扫描测量,并用WinRHIZ0软件进行单株总根长、根表面积和根体积的分析;可溶性糖含量用硫酸-蒽酮比色法测定;可溶性蛋白含量用考马斯亮蓝G-250染色法测定;脯氨酸含量用酸性茚三酮显色法测定.[结果]随着PEG6000浓度的增加,大麦幼苗生长受到明显抑制,株高逐渐降低,而根冠比则呈相反的变化趋势.就根系形态而言,随胁迫程度的增加,两套近等基因系表现出不同的变化趋势,在轻度和中度胁迫下3D和15T的变化幅度分别小于3T和15D,在重度胁迫下则表现相反.可溶性糖含量随胁迫浓度的增加呈先升高后降低再升高的变化趋势,而可溶性蛋白含量变化趋势与可溶性糖含量相反;在轻度和中度胁迫下3D和15D的变化幅度分别小于3T和15T,在重度胁迫下也表现相反.但脯氨酸含量随胁迫浓度升高呈现上升趋势,且在不同胁迫浓度下均表现为3D和15D变化幅度较小.相关分析表明:不同胁迫处理下,除可溶性蛋白含量外,株高与其他性状均存在显著相关关系;根冠比与根系形态以及根系形态之间也存在显著相关关系.同时,具有较高可溶性糖含量的品系其脯氨酸含量也较高,而可溶性蛋白含量则较低.此外,根系形态与叶片渗透调节物质之间亦存在一定的相关性,即总根长和根表面积均与可溶性糖含量和脯氨酸含量呈现显著负相关关系.[结论]在根系形态及叶片渗透调节方面,大麦株高近等基因系对苗期不同干旱胁迫的响应存在差异并相互影响.在轻度和中度胁迫程度下,近等基因系3T和3D中半矮秆基因的存在有利于抵御干旱胁迫.%[Objective]The aim of this study was to assess the relationship between the semi-dwarf gene uzu of barley and the drought resistance and to provide a theoretical basis for drought resistance and high quality breeding of barley.[Method] A hydroponic experiment was carried out to study the plant height,root-shoot ratio,root morphology and leaf osmoregulation substances of seedling of two pairs barley genotypes with different heights under different drought stress levels resulted by PEG6000 at different concentrations (0,5％,15％,25％).Samples were taken during seedlings grew to four leaves and a heart.Plant height was measured by ruler.Root-shoot ratio was calculated by root biomass to aboveground biomass ratio multiplied by 100％,which were obtained by drying and weighing.Total root length,root surface area and volume were measured and analyzed by root system scanner and the WinRHIZO software.The soluble sugar,soluble protein and proline content were determined by sulfuric acid-anthrone colorimetry,coomassie brilliant blue G-250 dyeing method and acidic indene three ketone chromogenic method,respectively.[Result] Analysis showed that barley seedling growth was significantly inhibited,and the plant height decreased gradually,while the opposite trend showed in the root-shoot ratio with the increase of stress concentration.In terms of root morphology,as the stress concentration increased,two pairs near-isogenic line showed different trends.The change range of 3D and 15T was less than that of 3T and 15D,respectively,under the mild and moderates tress,while the change range of 3D and 15T showed an opposite trend under severe stress.Furthermore,soluble sugar content showed an increase at first and then a decrease and an increase again with the increase of the stress concentration,while the opposite trend showed in soluble protein content.The change range was characterized by 3D＜ 3T,15D＜ 15T under the mild and moderate stress,and the change range of 3D and 15D also showed an opposite trend under severe stress.But the proline content presented a tendency of increasing with the increase of the stress concentration,and the small variations were characterized in 3D and 15D under different treatments.Correlation analysis indicated that plant height showed significant correlation with other traits in addition to the soluble protein content.There was also a significant relationship between root-shoot ratio and root morphology under different treatments.Meanwhile,the strains with higher soluble sugar content also had higher proline content,while the soluble protein content was low.Moreover,root morphology also had certain correlation with leaf osmoregulation substances,namely,the total root length and root surface area had significant negative relationship with soluble sugar content and proline content,respectively.[Conclusion] In the matter of root morphology and leaf osmoregulation,there are different responses under drought stress and influence with each other at seedling stage of barley genotypes with different heights.Under the mild and moderate stress,the semi-dwarf gene in the near-isogenic lines 3T and 3D can resist drought stress.