【作者】 马惠；

【导师】 阮颖；

【作者基本信息】 湖南农业大学 ， 植物学， 2012， 硕士

【摘要】 SDG26(SET domain group26)是一个组蛋白甲基转移酶基因。拟南芥SDG26基因功能缺失突变体sdg26具有莲座叶数量增多,叶片肥大,茎杆增粗,分枝增加,晚花和生长周期延长等表型。本研究以sdg26突变体为研究对象,观察其细胞学特征,对SDG26基因起始密码子上游序列进行了生物信息学分析。在此基础上对突变体sdg26在干旱和盐胁迫下,SOD、MDA、可溶性糖和脯氨酸含量等生理生化指标进行测定,观察分析根系的发育状况,阐明其在干旱和盐胁迫下生理生化指标变化规律和抗逆能力。获得了如下试验结果：1对突变体sdg26进行表型和组织切片观察发现：与Col相比,突变体的植株整体变得粗壮,侧枝增多,结实率增加。sdg26茎部的维管束数量增加,表皮细胞的层数增多,说明突变体茎杆的增粗是由于细胞数目的增多而引起的。2对SDG26基因启动子及其上游序列的分析发现：在启动子序列中存在多个能够响应逆境信号的顺式反应元件,他们分别是：8个WRKY710S、16、7个NODCON2GM和27个DOFCOREZM,暗示SDG26可能与逆境胁迫响应存在较密切的关系。3在干旱胁迫试验中,随着干旱时间(3、6、9、12、15天)的持续,sdg26中的SOD活性、MDA、可溶性糖和脯氨酸含量都表现出明显提高的趋势,且总体的上升水平显著高于对照Col中相应指标的上升水平。在干旱持续20天的条件下,对照Col失水死亡,而sdg26能正常生长,表现出良好的生长势,具有较强的抗旱能力。4在不同浓度(0、50、100、150、200mmol/LNaCl)盐胁迫下,突变体sdg26的萌发率分别为：98%、58%、17%、7%和1%；Col的萌发率分别为：98%,32%、7%、0.5%和0,sdg26在盐胁迫下的萌发率均高于Col。同时,sdg26中的SOD活性、MDA和游离脯氨酸的含量均高于Col,说明在受到盐害胁迫时,突变体sdg26的抗盐害能力强于Col。5根系的发育程度是植物抗逆能力的标志之一。在100mmol/LNaCl浓度的胁迫下,Col在受到胁迫的第5天后,根的生长发育趋势明显减缓,根系生长受到抑制,主根较短,侧根数目少,根长维持在6-8mm之间；而突变体sdg26仍能保持生长势,根长不断伸长,侧根数目较多,说明sdg26根系的抗盐能力高于Col。更多还原

【Abstract】 SDG26(SET domain group26) is a gene encoding histone methytransferase. In the background of sdg26defective mutants, plants shows phenotypes of increased number of rossete leaves, thicker leaf lamina, robust bolt, more branching, delayed flowering and expansion of growth period. This study investigate the cellular characteristics in sdg26and analyze the sequence upstream of SDG26gene initiation codon in bioformatics. Furthermore, The content level of SOD, MDA, soluble carbohydrate and proline been investigated in sdg26upon drought or salinity stress and studied the development of root system, elucidating the changes physical and chemical parameters and resistance upon drought and salinity. The results are listed followingly,1At the beginning, the study obtained homozygous sdg26mutant by T-DNA insertion, followed by observing phenotypes and tissue dissection. Compared to Col ecotype, the mutant shows robustness, more lateral branching and higher fertility.In the paraffin dissection of shoot, we found a increase of vascular bundle in sdg26. It suggest that the thickeness of shoot may be caused by the increase of cell number.2Via investigating the sequence upstream of SDG26gene initiation codon in bioformatics, we found that there are numerous adversity-responding cis-elements in the promoter, including8WRKY710S,16ARR1AT,7NODCON2GM and27DOFCOREZM. It suggests SDG26may respond to stress closely.3In the drought stress assessment, SOD activity, MDA, soluble carbohydrate and proline level showed obvious increase in sdg26with the drought continuation(3,6,9,12,15d), furthermore, the global level of these parameters is evidently higher than that in Col control. After20days drought, Col died of dehydration while sdg26showed normal growth and enhanced resistance to drought stress.4Upon a variety of concentration of salt stress (0,50,100,150,200mmol/L NaCl), the GR of sdg26is98%,58%,17%,7%and1%respectively while GR of Col is98%,32%,7%,0.5%and0. The sdg26shows pleiotropicly higher GR than Col upon salinity stress. At the same time, SOD activity, MDA, soluble carbohydrate and proline level showed full-scale increase in sdg26compared to Col, indicating resistance in sdg26is enhanced compared to Col under salt stress.5The development of root system is one of the markers in plant resistance. At5days post exposure100mmol/L NaCl stress. Col showed retained development of root system and shorter main root fewer lateral roots than normal. And the root length reached a plateau at6to8mm, in the contrast, sdg26remained normal growth and continuous elongation of roots and more lateral roots. That indicates resistance to high salinity in sdg26is enhanced compared to Col.更多还原