Enemies atpeace:Recentprogressin Agrobacterium-mediated cereal transformation

Agrobacterium tumefaciens mediated plant transformation is a versatile tool for plant genetic engineering following its discovery nearly half a century ago.Numerous modifications were made in its application to increase efficiency,especially in the recalcitrant major cereals plants.Recent breakthroughs in transformation efficiency continue its role as a mainstream technique in CRISPR/Cas-based genome editing and gene stacking.These modifications led to higher transformation frequency and lower but more stable transgene copies with the capability to revolutionize modern agriculture.In this review,we provide a brief overview of the history of Agrobacterium-mediated plant transformation and focus on the most recent progress to improve the system in both the Agrobacterium and the host recipient.A promising future for transformation in biotechnology and agriculture is predicted.

Mutation in the Agrobacterium his I gene enhances transient expression in pepper

Agrobacterium-mediated plant transformation is widely used in plant genetic engineering.However,its efficiency is limited by plant immunity against Agrobacterium.Chili pepper(Capsicum annuum L.)is an important vegetable that is recalcitrant to Agrobacterium-mediated transformation.In this work,Agrobacterium was found to induce a strong immune response in pepper,which might be the reason for T-DNA being difficult to express in pepper.An Agrobacterium mutant screen was conducted and a point mutation in the hisI gene was identified due to a weak immune response and enhanced transient expression mediated by this Agrobacterium mutant in pepper leaves.Further genetic analysis revealed that histidine biosynthesis deficiency caused by mutations in many genes of this pathway led to reduced pepper cell death,presumably due to reduced bacterial growth.However,mutation analysis of threonine and tryptophan biosynthesis genes showed that the biosynthesis of different amino acids may play different roles in Agrobacterium growth and stimulating the pepper immune response.The possible application of Agrobacterium amino acid biosynthesis mutations in plant biology was discussed.

Fast,simple,efficient Agrobacterium rhizogenes-mediated transformation system to non-heading Chinese cabbage with transgenic roots

Non-heading Chinese cabbage, a variety of Brassica campestris, is an important vegetable crop in the Yangtze River Basin of China. However,the immaturity of its stable transformation system and its low transformation efficiency limit gene function research on non-heading Chinese cabbage. Agrobacterium rhizogenes-mediated(ARM) transgenic technology is a rapid and effective transformation method that has not yet been established for non-heading Chinese cabbage plants. Here, we optimized conventional ARM approaches(one-step and two-step transformation methods) suitable for living non-heading Chinese cabbage plants in nonsterile environments. Transgenic roots in composite non-heading Chinese cabbage plants were identified using phenotypic detection, fluorescence observation, and PCR analysis. The transformation efficiency of a two-step method on four five-day-old non-heading Chinese cabbage seedlings(Suzhouqing, Huangmeigui, Wuyueman, and Sijiu Caixin) was 43.33%-51.09%, whereas using the stout hypocotyl resulted in a transformation efficiency of 54.88% for the 30-day-old Sijiu Caixin.The one-step method outperformed the two-step method;the transformation efficiency of different varieties was above 60%, and both methods can be used to obtain transgenic roots for functional studies within one month. Finally, optimized ARM transformation methods can easily,quickly, and effectively produce composite non-heading Chinese cabbage plants with transgenic roots, providing a reliable foundation for gene function research and non-heading Chinese cabbage genetic improvement breeding.

基于高遗传转化率及低幼苗玻璃化率的黑果枸杞叶片组合培养体系

【目的】建立高效稳定的黑果枸杞遗传转化体系,有效降低其再生幼苗玻璃化率,促进其基因功能研究和提高遗传改良效率。【方法】以黑果枸杞叶片作为外植体,利用农杆菌(LBA4404、EHA105)介导的遗传转化法,通过调整基础培养基类型并添加相应浓度的植物激素,筛选出最适愈伤组织诱导培养基、分化和选择培养基、生根诱导培养基,将黑果枸杞遗传转化率提高到65%以上,同时降低幼苗玻璃化率至10%以下。【结果】(1)黑果枸杞叶片高效组合培养体系中最佳农杆菌侵染浓度(OD_(600))为0.6,侵染时间为25 min,在此条件下侵染叶片抗性愈伤诱导率达78.2%~96%;(2)黑果枸杞遗传转化中最适分化和选择培养基为:MS+肌醇50 mg/L+烟酸0.25 mg/L+维生素B60.25 mg/L+铁盐母液1 mL/L+甘氨酸1.0 mg/L+维生素B10.05 mg/L+6-BA 0.25 mg/L+蔗糖30 g/L+琼脂6 g/L+卡那霉素30 mg/L+特美汀300 mg/L(pH=6.0);最适生根诱导培养基为:WPM+IBA 0.25 mg/L+蔗糖30 g/L+琼脂6 g/L+卡那霉素30 mg/L+特美汀300 mg/L(pH=6.0);(3)在最适分化和选择培养基中,农杆菌LBA4404-pBI121侵染叶片外植体产生的幼苗玻璃化率约为65%,而农杆菌EHA105-pBI121侵染处理则低于10%;(4)采用木本植物低盐WPM培养基可使黑果枸杞再生幼苗生根效率达到81.2%左右。(5)将阳性愈伤数量与总接种叶片数量比值作为遗传转化效率的评价指标,在最适遗传转化体系中,农杆菌LBA4404-pBI121和EHA105-pBI121侵染后遗传转化率分别为51%和65.2%。【结论】黑果枸杞叶片高效组合培养体系能够显著提高其遗传转化率,降低玻璃化幼苗的发生率。

根癌农杆菌介导的紫花苜蓿遗传转化体系的优化

为进一步提高根癌农杆菌介导的紫花苜蓿遗传转化效率,本试验以紫花苜蓿(Medicago sativa L.)品种‘中苜1号’为试验材料,通过筛选高效再生的植株,以筛选出的植株叶片为外植体,并通过调节培养基激素配比,在农杆菌侵染过程中添加谷氨酰胺、进行冷处理等措施优化苜蓿由农杆菌介导的遗传转化体系。试验结果表明:转化过程中以嫩叶作为外植体,菌液和重悬液中添加150μmol·L^(-1)乙酰丁香酮,侵染过程中使用300μmol·L^(-1)的谷氨酰胺将瞬时转化效率从32%提高至92%,转化效率提高到31%。研究紫花苜蓿的遗传转化体系可为紫花苜蓿高效遗传改良及基因功能研究提供了技术支持。

发根农杆菌介导的甜瓜CRISPR/Cas9系统靶位点的检测

选取甜瓜栽培材料龙庆八号作为受体材料,构建CmCURT1A基因CRISPR/Cas9基因编辑载体,经发根农杆菌介导检测靶位点的编辑情况,为后续甜瓜遗传转化试验提供载体基础。以甜瓜CmCURT1A基因(ID:MELO3C006053.2)为靶基因构建双靶位点敲除载体,经发根农杆菌K599介导的简单遗传转化技术使甜瓜组织长出不定根,经PCR测序发现在不定根中分别存在65 bp、72 bp不同碱基片段的缺失。该方法成功进行了甜瓜CRISPR/Cas9载体靶位点敲除情况的检测,简单高效,实现了在甜瓜中基因编辑靶点的快速鉴定,为研究甜瓜基因功能和遗传改良奠定基础。

Agrobacterium _mediated Transformation of Rice with Help of Bombardment

Oryza sativa L. ssp. japonica cv. Zhonghua 8, which is recalcitrant to infection of Agrobacterium tumefaciens (Smith et Townsend) Conn strain EHA105 with ordinary binary vector pCambia 1301, was transformed through Agrobacterium-mediated transformation with help of bombardment. The transformation efficiency can be raised greatly. Single copy of gene insertion in the genome of transgenic rice plants was proved by Southern analysis and the expression of GUS gene was observed. GUS gene and hygromycin-resistant gene show 3:1 segregation in progenies of the transgenic rice plants.

Researches of Agrobacterium rhizogenes Ri Plasmid rol Genes

Expression of rol genes from Ri plasmid of Agrobacterium rhizogenes not only leads to the excessive formation of adventitious roots, but also exhibits various genetically modified characteristics that have broad prospects for the application of plant genetic improvement. Since the 1980s of the last century, much progress has been made in the studies of A. rhizogenes, in particular the agropine type Ri plasmid rol genes and their applications for plant genetic improvement, which involves the structure and function of Ri plasmid, the characters of rol genes, the influence of rol genes expression on plants growth and development, and the applications of rol genes for genetic improvement of forest tree. In this paper, the advances in this field are reviewed and the existing problems about the application of rol genes for genetic improvement of forest tree are also discussed.

石油生物催化脱硫菌Agrobacterium tumefaciens UP3的分离筛选

从胜利油田被原油污染的土壤中筛选到一株能有效降解模型化合物二苯并噻吩 (DBT)的菌株。根据常规的形态分析、生理生化性状及 16SrDNA序列分析 ,将其鉴定为根癌土壤杆菌 (AgrobacteriumtumefaciensUP3)。该菌不能以十二烷、十六烷、液体石蜡和萘作为唯一碳源和能源生长 ,具有工业应用的潜力。对该菌株DBT降解能力的初步研究表明 ,5 4h内可将 5 0 0mg L的DBT降解至 15 0mg L。对降解产物的分析表明 ,根癌土壤杆菌降解DBT的途径与Kodama路线及 4_S路线不同。

Genetic Transformation of Aloe barbadensis Miller by Agrobacterium tumefaciens

Despite the importance of aloe in cosmetic and pharmaceutical industries, improvement of aloe （Aloe barbadensis Miller） by genetic engineering was seldom reported previously. In this study, regeneration and transformation conditions, including explant selection and surface sterilization, use of different Agrobacterium strains, and co-culture processing, are optimized. The use of 20.0% sodium hypochloride （25 rain） for sterilization was less detrimental to the health of explant than 0.1% mercuric chloride （10 min）. Regeneration frequency from stems was much higher than that from leaves or sheaths. Explants were infected by Agrobacterium （30 rain） in liquid co-cultural medium, and this was followed by three days co-culture on sterile filter papers with light for 10 h per day at 24℃. Histochemical data demonstrated that the transient expression of GUS gene in the stem explants of aloe infected with Agrobacterium strains EHAI05 and C58CI was 80.0% and 30.0%, respectively, suggesting the higher sensitivity of the explants to EHAI05 than to C58C1. Infected tissues were selected using G418 （10.0-25.0 mg/L） to generate transformants. Sixty-seven G418 resistant plantlets were generated from the infected explants. Southern blotting, PCR, and ELISA analyses indicated that the alien gene were successfully transferred into aloe and was expressed in the transgenic plants. This newly established transformation system could be used for the genetic improvement of aloe.

不同外源物质对蒙古栎插穗生根及基部生理生化的影响

[目的]扦插是苗木良种繁育的一种重要途径,适宜外源物质的应用能促进插穗生根。蒙古栎扦插生根困难,探究不同浓度外源物质及其组合应用对蒙古栎嫩枝扦插生根的影响,为蒙古栎规模化扦插育苗提供技术支持。[方法]采用速蘸法或浸泡法,使用不同浓度吲哚丁酸钾(IBA-K)、生根粉(ABT1)、K599发根农杆菌、丙环唑(PCZ)及其组合应用处理插穗,测定插穗生根率、愈伤率、生根数、根长、营养物质含量、酶活性和内源激素含量变化等。[结果]不同外源物质单独处理时,K599发根农杆菌(OD600=0.8)浸泡30 min后插穗生根率最高,可达24.71%。50μmol·L^(−1)PCZ浸泡2 h后插穗根部愈伤率最高,达43.62%。其它外源物质单独处理时,插穗生根效果差。不同外源物质组合应用时,50μmol·L^(−1)PCZ浸泡2 h结合K599发根农杆菌(OD600=0.8)浸泡30 min可显著提高蒙古栎插穗生根,生根率可达36.37%,愈伤率达51.14%,平均生根数及根长分别为2.25和5.72 cm。此外,研究结果表明,PCZ能够加快插穗生根过程中可溶性糖和蛋白消耗,促进过氧化物酶(POD)和多酚氧化酶(PPO)活性,提高不定根诱导期IAA含量,增加IAA/ABA和IAA/ZR比值。[结论]PCZ结合发根农杆菌K599组合应用能够显著提高蒙古栎嫩枝扦插生根率。营养物质(可溶性糖、蛋白)消耗慢、抗氧化酶(PPO、POD)活性弱、IAA含量低可能是蒙古栎扦插生根难的主要原因,而PCZ对此具有重要抑制作用,可在蒙古栎等扦插难生根物种中发挥重要作用。

农杆菌介导的黄瓜遗传转化体系优化研究

【目的】筛选适用于农杆菌介导的黄瓜遗传转化体系,为通过生物技术进行黄瓜新品种培育奠定基础。【方法】以华北型黄瓜品种‘9930’子叶为试材,探讨卡那霉素浓度(kanamycin, Kan)、预培养时间、预培养基添加乙酰丁香酮(acetosyringone, AS)、分化培养基pH及生根培养基中添加不同外源物质对黄瓜遗传转化的影响。【结果】不定芽分化、生根阶段的Kan临界浓度为150 mg/L;不进行预培养的黄瓜不定芽诱导率最高,为77.17%;当分化培养基pH为5.6时不定芽诱导率最高,为75.26%;外植体在添加0.5 mg/L的IBA生根培养基上生根率达100%,根长也显著增加。【结论】在以黄瓜品种‘9930’子叶节为外植体的遗传转化体系中,150 mg/L Kan可作为不定芽分化和生根阶段的筛选选择压;不进行预培养更有利于其抗性芽诱导;适合不定芽诱导的分化培养基pH为5.6;0.5 mg/L的IBA为诱导外植体生根最佳激素浓度。

平邑甜茶发根农杆菌介导转化体系构建与优化

【目的】建立并优化平邑甜茶(Malus hupehensis Rehd.)幼苗简单、高效、快速的发根农杆菌转化体系。【方法】以不同苗龄的平邑甜茶幼苗为材料,使用携带GFP及GUS过表达质粒的发根农杆菌K599,通过注射法、活化菌液浸染及菌株涂抹方法侵染平邑甜茶根颈部诱导毛状根,利用GFP荧光检测、GFP蛋白印迹检测、DNA检测和GUS染色方法进行转基因株系验证,同时对成功转化株系根、茎、叶组织的表达量进行分析,检测发根农杆菌在转化平邑甜茶株系中的迁移性。【结果】不同苗龄平邑甜茶幼苗诱导毛状根能力具有较大差异,其中三叶龄幼苗诱导毛状根率最高,为96%,五叶龄幼苗最高的毛状根诱导率为65%,以使用菌株涂抹方式转化植株的毛状根分布为最佳、毛状根诱导率为最高。发根农杆菌在成功转化株系中存在随机向地上部迁移的现象,并能够整合目的基因至叶片叶柄及部分主叶脉基因组中,但在培养30 d时无法通过蛋白印迹方式在蛋白水平上检测到蛋白信号。【结论】建立并优化了简单、高效的发根农杆菌介导的平邑甜茶转化体系,鉴定了发根农杆菌在转化株系中随机向地上部迁移规律,为发根农杆菌技术的进一步利用提供理论依据。

根癌农杆菌介导彩色马蹄莲遗传转化体系的建立及优化

【目的】建立及优化根癌农杆菌介导的彩色马蹄莲(Zantedeschia hybrida)遗传转化体系,为提高彩色马蹄莲遗传转化效率及培育彩色马蹄莲抗性品种提供理论参考依据。【方法】将不同外植体(茎基、叶、不定芽)和不同浓度噻苯隆(TDZ)(0.001、0.002和0.005 g/L)进行正交试验筛选外植体和丛生芽增殖培养基;液氮冻融法将pCAM BIA2301和pBI121质粒转入农杆菌LBA4404感受态细胞。以β-葡萄糖苷酸酶(GUS)基因作为农杆菌介导转化测定的报告基因,对彩色马蹄莲的丛生芽进行遗传转化,阳性苗经PCR扩增验证转化结果。通过不同硫酸卡那霉素(Kan)浓度(50、100和150 mg/L)、侵染时间(25、30和40 min)及共培养时间(2和3 d)3因素正交试验筛选最佳转化条件。【结果】外植体为不定芽的丛生芽诱导率极显著高于茎基和叶(P<0.01),当不定芽为外植体、TDZ浓度为0.002 mg/L时,丛生芽增殖倍数(5.12倍)显著高于0.001和0.005 mg/L TDZ处理(P<0.05),筛选出M6培养基+0.002 mg/L TDZ+30 g/L蔗糖+6.25 g/L琼脂为丛生芽增殖培养基;影响阳性频率因素排序为:侵染时间>Kan浓度>共培养时间。当Kan浓度为50 mg/L、侵染时间25 min及共培养时间为3 d为最优侵染条件,此时,GUS+丛生芽出芽频率和PCR阳性频率最高,分别为54.0%和15.27%。【结论】成功优化彩色马蹄莲遗传转化体系,最佳外植体为不定芽,转化体系最佳组合为Kan浓度为50 mg/L、侵染时间为25 min及共培养时间为3 d。

不同甜瓜品种遗传转化再生体系的建立与基因编辑植株的快速获取

【目的】研究不同甜瓜品种遗传转化再生体系的建立与基因编辑植株的快速获取。【方法】选用巴吾顿、老汉瓜、其里甘、新密杂11号(86-1)4个甜瓜品种的子叶为外植体,通过农杆菌介导法侵染甜瓜子叶,采用组织培养法建立老汉瓜的遗传转化再生体系,运用PCR法检测获取基因编辑植株。【结果】从4个甜瓜品种中筛选出老汉瓜为优势品种作为外植体,在MS+6-BA 1.0 mg/L+NAA 0.05 mg/L培养基预培养2 d和共培养3 d,在MS+6-BA 1.0 mg/L+NAA 0.05 mg/L+潮霉素5 mg/L+头孢霉素250 mg/L筛选培养基上继续培养7 d,在MS+6-BA 1.0 mg/L+NAA 0.05 mg/L+潮霉素5 mg/L+头孢霉素250 mg/L的不定芽诱导培养基上培养1~2周可见长出的小芽,将诱导芽分别放置于不加潮霉素和加潮霉素的芽伸长培养基上培养,诱导芽在不加潮霉素的芽伸长培养基上的生长速度比加潮霉素的培养基生长快,可使芽生长至2叶苗期缩短3周,在无菌环境下剪去一个芽提取DNA,并采用RT-PCR方法检测获得21株转化植株。【结论】筛选出基因编辑植株嫩芽,不加潮霉素的芽伸长培养基可将获得基因编辑植株周期缩短3周。

川西高原酿酒葡萄根癌病病原菌的鉴定及防治药剂筛选

【目的】明确川西高原酿酒葡萄根癌病的致病菌种类,评价不同药剂对病原菌的抑制及对根癌病的防治效果。【方法】采集川西高原酿酒葡萄根瘤组织进行病原菌的分离纯化,通过形态观察、生理生化鉴定、PCR检测及16s rDNA测序分析确定分离菌株种类,并对分离菌株进行系统进化分析(极大似然法maximum-likelihood)、生长特性分析及致病性检测。利用皿内抑菌圈法初步研究不同药剂对病原菌的抑制作用,并通过葡萄苗接种试验明确药剂对根癌病的防治效果。【结果】成功由葡萄根瘤组织中分离得到9株菌株,经鉴定为生物Ⅲ型葡萄土壤杆菌(Agrobacterium vitis),进化分析表明,9株菌株聚类在同一分支。虽然9株菌株生长特性略有差异,但均能使胡萝卜及葡萄形成瘿瘤,有致病性。进一步研究11种商品化药剂对分离菌株的抑制效果,发现中生菌素、福美双、多菌灵、春雷霉素、枯草芽孢杆菌和氢氧化铜对分离菌株抑制效果微弱或无效果,对分离菌株抑制效果较好的依次为四霉素、百菌清、喹啉铜、解淀粉芽孢杆菌KN-527及乙蒜素。进一步验证这5种效果较好的药剂对葡萄根癌病的防治效果,其中乙蒜素对葡萄根癌病的防治效果最好,发病率仅为6%,防治效果高达48.05%;其次,喹啉铜及四霉素对葡萄根癌病有防治效果;在所试药剂中,百菌清及解淀粉芽孢杆菌KN-527的防治效果较差。【结论】川西高原酿酒葡萄根癌病的致病菌为葡萄土壤杆菌,对酿酒葡萄根癌病防治效果最好的为乙蒜素,然后依次为喹啉铜、四霉素、百菌清及解淀粉芽孢杆菌KN-527。其中乙蒜素在根癌病田间防治可能具有较广阔的应用前景,生防菌株解淀粉芽孢杆菌KN-527对早期葡萄根癌病的发生有抑制作用。

耐盐芦苇高频遗传转化体系的建立

以耐盐芦苇(Phragmites australis)种子愈伤组织为材料,以根瘤农杆菌EHA105为媒介建立高效的芦苇遗传转化体系。结果表明:在潮霉素浓度为50 mg/L、6-BA浓度为0.8 mg/L时不定芽分化率达到最高。将沉默载体pFGC1008-GRPi通过根瘤农杆菌EHA105在芦苇愈伤组织中进行遗传转化,共获得8个抗性株系,转化率为3.9%。实时荧光定量PCR检测显示6个株系实现了基因沉默,表明该转化体系高效可用。

异养硝化好氧反硝化菌株Agrobacterium tumefaciens LAD9羟胺氧化酶的分离纯化

羟氨氧化酶(Hydroxylamine oxidase,HAO)的作用方式直接决定了异养硝化好氧反硝化细菌的代谢途径,分离得到纯度较高的HAO也就成为研究这类细菌脱氮机制的重要环节。以异养硝化好氧反硝化细菌Agrobacterium tumefaciens LAD9为代表,建立了该菌株HAO的分离纯化方法:首先采用渗透压休克法提取细胞周质液,然后采用DEAE Sepharose CL-6B离子交换层析和Sephacryl S-100凝胶过滤层析对细胞周质液进行分离纯化。结果表明,经过离子交换层析可得到分子量分别为55.3、35.7和19.2kD的杂蛋白,进一步经过凝胶过滤层析即可得到电泳纯的HAO,纯化倍数为5.79,产率为39.71%。对其酶学性质的初步研究表明,该菌株HAO的分子量为18.8 kD,能够将羟胺氧化为亚硝酸盐氮,且Fe2+的加入可显著增强其酶活。

光果柱花草转基因毛状根及其原生质体制备体系的建立

光果柱花草(Stylosanthes leiocarpa)是柱花草属(Stylosanthes Sw.)中可用于林果园间作的一个野生种。截至目前,光果柱花草的转基因体系尚未建立。本研究以光果柱花草的子叶节为外植体,比较不同的发根农杆菌菌株与潮霉素B浓度对毛状根诱导率及转基因阳性率的影响。结果发现,以K599为诱导菌株且培养基添加8 mg·L^(-1)潮霉素B为筛选压,是最优的毛状根诱导条件,诱导率达23.33%,阳性率为100%。在此基础上,利用转基因毛状根制备原生质体,结果表明,添加2.5%纤维素酶和2%离析酶,以及8 h的酶解时间为最优条件,原生质体的产量达2.745×10^(5)个·g^(-1),活力为91.02%,制备的原生质体100%为转基因细胞。本研究成功建立了一种发根农杆菌介导的光果柱花草转基因毛状根诱导体系及原生质体制备体系,为后续光果柱花草的基因功能研究奠定了基础。

车前(lantago asiatica L.)毛状根诱导技术研究

为建立发根农杆菌Ri质粒介导的车前(lantago asiatica L.)转化体系,通过发根农杆菌A4和R1601侵染车前无菌苗的外植体诱导毛状根.实验结果表明,车前外植体最佳侵染时间为8 min;两种菌液均可以诱导车前叶片、叶柄和根产生毛状根,车前叶片和叶柄毛状根的诱导率低于40%,车前根部毛状根的诱导率高于80%;经过分子鉴定,Ri质粒T-DNA的rolB基因已成功整合到毛状根中,表明车前的根是适宜毛状根诱导的最佳外植体,可为今后车前毛状根的扩大培养奠定基础.