Overexpression of Populus euphratica PEPKR2 negatively regulates cadmium tolerance in Arabidopsis thaliana
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摘要:目的
磷酸烯醇丙酮酸羧化酶激酶相关激酶（PEPKRs）是植物特有的CDPK/SnRK超家族成员，但其在胡杨响应重金属胁迫中的调控机制尚不清楚。本文通过研究胡杨PEPKR2在镉胁迫过程中的作用，旨在进一步揭示植物响应镉胁迫的生理与分子调控机制。
方法克隆胡杨PEPKR2基因，利用DNAMAN进行同源氨基酸序列比对，并用Mega 7软件构建进化树。以野生型（WT）、转空载体对照（VC）和过表达PePEPKR2拟南芥（PePEPKR2-OE1、PePEPKR2-OE7和PePEPKR2-OE11）株系为实验材料，对各株系拟南芥进行不同浓度的镉处理，从生理和分子水平探究PePEPKR2在植物响应镉胁迫中的作用机制。
结果（1）胡杨PEPKR2氨基酸序列与毛果杨PEPKR2相似度最高，亲缘关系最近；镉胁迫处理之后，胡杨根、茎、叶中PEPKR2表达量均发生了显著性变化；PePEPKR2蛋白定位于细胞核中。（2）在镉胁迫条件下，过表达PePEPKR2的拟南芥株系的根长、存活率和鲜质量均低于WT和VC，而相对电导率显著高于WT和VC，表明过表达株系对镉胁迫更敏感。（3）镉胁迫处理后，相较于WT和VC，过表达拟南芥株系的幼苗根尖Cd2+ 内流速度显著加快，Cd2+含量也显著升高；土培条件下，过表达株系的根和叶中Cd2+ 含量均显著高于WT和VC。（4）镉胁迫处理后，过表达拟南芥株系的超氧化物歧化酶和过氧化氢酶活性的升高幅度均低于WT和VC，过氧化物酶活性的降低幅度均高于WT和VC，抗氧化酶相关基因的转录水平变化与酶活性的变化趋势一致；最终导致过表达拟南芥株系根尖的H2O2含量显著高于WT和VC。（5）土培条件下，经镉胁迫处理后，过表达拟南芥株系的叶绿素相对含量、最大光化学效率、实际光化学效率、电子传递速率、净光合速率、蒸腾速率、气孔导度均低于WT和VC，而细胞间CO2浓度则高于WT和VC。
结论过表达PePEPKR2增加了Cd2+ 在拟南芥中的积累，削弱了活性氧清除能力，进而使光合系统功能紊乱，最终负调控拟南芥的镉耐受性。本研究为利用基因工程改良杨树的镉修复能力提供了理论支持。
Abstract:ObjectivePhosphoenolpyruvate carboxylase kinase-related kinases (PEPKRs), belonging to the plant-exclusive CDPK/SnRK superfamily, have not yet been fully elucidated in terms of their regulatory mechanisms underlying the heavy metal stress response in Populus euphratica. This study investigated the role of Populus euphratica PEPKR2 during cadmium (Cd) stress to further elucidate the physiological and molecular regulatory mechanisms underlying plant responses to Cd toxicity.
MethodThe PEPKR2 gene was cloned from P. euphratica, and the DNAMAN was used for homologous amino acid sequence alignment, while a phylogenetic tree was constructed using Mega 7 software. Using wild-type (WT), empty vector control (VC), and PePEPKR2-overexpressing Arabidopsis thaliana lines (PePEPKR2-OE1, PePEPKR2-OE7, and PePEPKR2-OE11) as experimental materials, plants were subjected to graded cadmium treatments to investigate the mechanistic role of PePEPKR2 in plant responses to Cd stress at both physiological and molecular levels.
Result(1) The amino acid sequence of P. euphratica PEPKR2 (PePEPKR2) exhibited the highest sequence similarity and closest phylogenetic relationship with its ortholog in Populus trichocarpa. Following cadmium stress treatment, differential expression patterns of PEPKR2 were observed across root, stem, and leaf tissues in P. euphratica, with statistically significant alterations in transcript abundance. Subcellular localization assays confirmed the nuclear compartmentalization of PePEPKR2 protein. (2) Under cadmium stress conditions, PePEPKR2-overexpressing plants exhibited significantly reduced root elongation, survival rate, and fresh biomass compared with WT and VC plants, whereas relative electrolyte leakage was markedly elevated. These phenotypic divergences collectively demonstrated hypersensitivity of PePEPKR2-overexpressing lines to Cd toxicity. (3) Following cadmium stress exposure, PePEPKR2-overexpressing plants exhibited significantly accelerated Cd2+ influx rates and elevated Cd2+ accumulation in root tips compared with WT and VC plants. Furthermore, under soil-grown conditions, transgenic lines demonstrated markedly higher Cd2+ concentrations in both roots and leaves relative to WT and VC plants. (4) Under cadmium stress, the PePEPKR2-overexpressing plants exhibited smaller increases in superoxide dismutase and catalase activities, but greater decreases in peroxidase activity compared with WT and VC plants. These changes in antioxidant enzyme activities were consistent with the transcriptional patterns of their corresponding genes. Consequently, the PePEPKR2-overexpressing lines accumulated significantly higher levels of H2O2 in root tips than the controls. Under soil culture conditions, after cadmium stress treatment, overexpressed lines exhibited lower relative chlorophyll content, maximum photochemical efficiency, actual photochemical efficiency, electron transport rate, net photosynthetic rate, transpiration rate, and stomatal conductance while higher intercellular CO2 concentration than the WT and VC lines.
ConclusionOverexpression of PePEPKR2 enhanced Cd2+ accumulation in Arabidopsis thaliana, compromised reactive oxygen species (ROS) scavenging capacity, and subsequently disrupted photosynthetic function, ultimately conferring negative regulation of Cd tolerance. This study provides theoretical support for genetic engineering approaches to improve cadmium phytoremediation potential in Populus species.
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Keywords:
- Populus euphratica /
- protein kinase /
- PePEPKR2 /
- cadmium stress /
- reactive oxygen species /
- photosynthesis /
- transgenosis
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植物的寿命是其生活史上一个重要的特征，准确判断植物的生长年龄对理解植物在特定环境中的发育和繁殖更新状况，评估其生长影响因子及环境适应能力，由此制定合理的栽培管理及开发利用措施意义重大[1-5]。植物生长年龄一般可以通过周年生长形态、物候及生长轮等进行分析。在木本植物中，多年生茎中的年轮解剖结构特征可以反映其实际生长年限及生长发育状况[1,6]。研究表明，多年生草本植物位于地下的宿存器官（根茎，块茎，块根和鳞茎）中存在类似树木年轮的“生长轮”可以作为其生长年限判别的依据[1]。根茎是根茎类植物营养物质的重要贮存场所[7-9]，也是其自然更新和分株繁殖的主要器官，是芽与根生理整合的枢纽通道[10]，对根茎的形态特征、次生结构及其生长年龄的研究是揭示其生长发育及环境适应机制的重要基础，因而受到广泛关注。目前，对根茎生长年龄的判断一方面是根据其世代繁殖更新的形态特征来确定[2-5]，另一方面可以通过其生长轮来进行判断，在灰白千里光（Senecio incanus），草甸鼠尾草（Salvia pratensis ）及奇异蜂斗菜（Petasites paradoxus）等植物的根茎中均发现有生长轮的存在[1]。
芍药（herbaceous peony）是典型的根茎类多年生草本植物，野生遗传资源丰富[11]，栽培品种繁多，形成了3大品种类群[12-15]，有重要的观赏和药用价值[16-17]。目前关于芍药根茎的研究报道较少，仅对中国芍药品种群的个别品种的根茎生长发育及初生组织结构特征进行了初步的研究[18]，对芍药根茎中是否存在生长轮以及不同品种间的生长轮差异尚未有报道。因此，本研究通过比较观察分析不同芍药品种群品种的根茎形态生长发育特点，对芍药根茎进行解剖学研究，观察其生长轮特点，判别其生长年限，以期为芍药合理栽培措施的制定、无性繁殖技术的优化及资源的开发利用研究提供一定的基础理论指导。研究结果对其他多年生根茎类植物的生长年龄判断及相关研究的开展也具有一定的借鉴意义。
1. 材料与方法
1.1 材 料
芍药不同品种群品种（表1），种植于国家花卉工程中心芍药种质资源圃（北京昌平区小汤山镇），供试材料为3年生分株苗。
表 1 供试芍药品种信息Table 1. Variety information of experimental materials编号 No. 品种名称 Variety name 品种群分类 Classification of cultivar groups 倍性 Ploidy level 1 ‘种生粉’ ‘Zhongshengfen’ 中国芍药品种群 Lactiflora group 2n = 2x = 10 2 ‘粉玉奴’ ‘Fenyunu’ 中国芍药品种群 Lactiflora group 2n = 2x = 10 3 ‘珊瑚落日’ ‘Coral Sunset’ 杂种芍药品种群 Hybrid group 2n = 3x = 15 4 ‘乳霜之愉’ ‘Cream Delight’ 杂种芍药品种群 Hybrid group 2n = 4x = 20 5 ‘草原风情’ ‘Prairie Charm’ 伊藤杂种品种群 Itoh hybrid group 2n = 3x = 15 6 ‘抓狂的香蕉’ ‘Going Bananas’ 伊藤杂种品种群 Itoh hybrid group 2n = 3x = 15 1.2 方 法
1.2.1 芍药地下根茎发育更新特点观察
于2018年9月中旬至11月底，剪除芍药地上枯茎，将地下根茎整体起挖，去除泥土、杂物，沿根茎生长方向将其理顺并去除多余的肉质根以使根茎清晰可见，拍照观察并记录芍药根茎的生长更新特征。
1.2.2 芍药不同品种地下根茎解剖结构观察
选取不同品种当年生根茎芽基部1 cm以下的成熟根茎组织，沿其横轴切取约2 mm的薄片，FAA固定液（50%乙醇∶甲醛∶冰醋酸 = 90∶5∶5，体积比）真空固定处理24 h以上，随后加入约1/5 FAA体积甘油软化处理10 d以上，随后经脱水，透明，浸蜡，包埋后切片，切片厚度16 ~ 25 μm，经固绿−番红染色后中性树胶封片，Leica EZ4HD体式显微镜观察和拍照。
1.2.3 芍药根茎生长轮观察
体式显微观察：按照根茎的着生规律，切取发育正常的不同生长年限的根茎，冰盒保存带至实验室，用自来水冲洗3遍，去除根茎表面的泥土及其他杂质，置于吸水纸上室温晾1 ~ 2 h左右，观察时不锈钢刀片沿其横轴方向截平，将切口晾3 ~ 5 min后Leica EZ4HD体式显微镜拍照观察。
石蜡切片制备：按照根茎的着生规律，选取发育正常的芍药不同生长年限的根茎按1.2.2所述方法进行切片观察。
2. 结果与分析
2.1 芍药地下根茎结构发育特点
不同芍药品种群品种植株地下的组织架构基本一致，即由根茎、着生于根茎上的根茎芽和根3部分组成，根茎与肉质根在颜色上基本一致，除顶部根茎上着生的根茎芽外，下部根茎上也宿存大量处于休眠状态的根茎芽。正常发育的芍药地下根茎发育形态具有较明显的年龄分级特征，我们把当年根茎芽萌发后形成的根茎作为1龄生根茎，则1龄生根茎所着生的上一年形成的母代根茎则为2龄生根茎，2龄生根茎所着生的上一年形成的母代根茎为3龄生根茎，以此类推，各生长年限的根茎之间以根茎上宿存的茎或者残留的茎痕为界，偶见有当年生根茎着生于2龄以上的母代根茎（图1）。
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图 1 芍药根茎结构发育示意1YR：1龄生根茎；2YR：2龄生根茎；3YR：3龄生根茎；4YR：4龄生根茎；5YR：5龄生根茎；RB：根茎芽；St：茎；AR：不定根。1YR, 1 year old rhizome; 2YR, 2 years old rhizome; 3YR, 3 years old rhizome; 4YR, 4 years old rhizome; 5YR, 5 years old rhizome; RB, rhizome bud; St, stem; AR, adventitious root.Figure 1. Structural characteristic of rhizome of herbaceous peony‘种生粉’‘粉玉奴’‘Coral Sunset’‘Prairie Charm’和‘Going Bananas’5个品种地下根茎结构形态类似：每年的纵向（长度）生长量适中且横向（直径）膨大变异较小，不同龄级的根茎组织结构易于区分，且根茎背地向上更新（图2a、b）。四倍体品种‘Cream Delight’每年纵向生长量小而横向生长量较大，膨大明显，不同龄级的根茎组织结构紧凑而不易区分，且往往与地表水平方向横向更新（图2c、d）。
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图 2 芍药不同品种地下根茎发育结构特征a、b. ‘珊瑚落日’根茎；c、d. ‘草原风情’根茎；RB：根茎芽；Rt：根；Rh：根茎；St：茎。a, b, the rhizome of‘Coral Sunset’; c, d, the rhizome of ‘Cream Delight’; RB, rhizome bud; Rt, root; Rh, rhizome; St, stem.Figure 2. Structural characteristics of rhizomes of different cultivars of herbaceous peony6个芍药品种根茎截面解剖构造均符合双子叶植物茎的次生构造，由周皮、皮层、次生韧皮部、形成层、次生木质部和中央髓组成（图3）。
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图 3 不同品种根茎解剖结构a、b. ‘大富贵’根茎解剖结构；c、d. ‘粉玉奴’根茎解剖结构；e、f. ‘珊瑚落日’根茎解剖结构；g、h. ‘乳霜之愉’根茎解剖结构；i、j. ‘草原风情’根茎解剖结构；k、l. ‘抓狂的香蕉’根茎解剖结构；Pe：周皮；Sp：次生韧皮部；Vc：维管形成层；Sx：次生木质部；Pi：髓。标尺 = 1 000 μm。a, b, rhizome anatomy of ‘Dafugui’; c, d, rhizome anatomy of ‘Fenyunu’; e, f, rhizome anatomy of ‘Coral Sunset’; g, h, rhizome anatomy of ‘Cream Delight’; i, j, rhizome anatomy of ‘Prairie Charm’; k, l, rhizome anatomy of ‘Going Bananas’; Pe, periderm; Sp, secondary phloem; Vc, vascular cambium; Sx, secondary xylem; Pi, pith. Scale bar = 1 000 μm.Figure 3. Anatomical structure of rhizomes of different cultivars of herbaceous peony‘种生粉’‘粉玉奴’‘Coral Sunset’和‘Cream Delight’4个品种根茎次生木质部显微结构类似：大小导管有规律地依次排列，口径较大的导管和周围的小导管聚集形成群团状，导管群分布较稀疏，两导管群之间的间隔明显。与‘Cream Delight’相比，‘Coral Sunset’的导管群分布较紧凑。‘Prairie Charm’和‘Going Bananas’根茎的次生木质部大小导管分布较均匀，形成较连续的环带，并不聚集形成团块状（图3）。
2.2 芍药不同生长年限根茎横切面特征
芍药根茎截面在脱水后维管组织凸起，呈白色或淡黄色，间断环状分布，中央髓部组织下凹，位于不同环的维管组织从髓部向皮层呈放射状排列（图4）。
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图 4 芍药‘粉玉奴’根茎横切面结构a、b. 2龄生根茎；c、d. 6龄生根茎；Sx：次生木质部；Pi：髓。标尺 = 1 000 μm。a, b, 2 years old rhizome; c, d, 6 years old rhizome; Sx, secondary xylem; Pi, pith. Scale bar = 1 000 μm.Figure 4. Cross section structure of rhizome of Paeonia lactiflora ‘Fenyunu’次生木质部显微观察结果显示，口径较大的导管及其周围的小导管聚集呈团块状，导管群切向断续排列成与形成层平行的环，形成清晰的生长轮（图5）。
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图 5 芍药‘粉玉奴’根茎横切面显微结构a. 2龄生根茎；b. 4龄生根茎；Vc：维管形成层；Pi：髓。标尺 = 1 000 μm。a, 2 years old rhizome; b, 4 years old rhizome; Vc, vascular cambium; Pi, pith. Scale bar = 1 000 μm.Figure 5. Microstructure of the cross section of the rhizome of Paeonia lactiflora ‘Fenyunu’对生长发育正常的芍药不同生长年限根茎进行组织切片观察发现，一年生根茎生长轮数目为1（图6a），2年生根茎生长轮的数目为2（图6b），3年生根茎的生长轮数目为3（图6c），依此类推。生长轮的数目与其实际生长年限一致。
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图 6 芍药根茎不同生长年限生长轮观察a. 1龄生根茎；b. 2龄生根茎；c. 3龄生根茎；d. 4龄生根茎；e. 5龄生根茎；f、g. 6龄生根茎；h、i. 7龄生根茎；①. 第1个生长轮；②. 第2个生长轮；③. 第3个生长轮；④. 第4个生长轮；⑤. 第5个生长轮；⑥. 第6个生长轮；⑦. 第7个生长轮。标尺 = 1 000 μm。a, 1 year old rhizome; b, 2 years old rhizome; c, 3 years old rhizome; d, 4 years old rhizome; e, 5 years old rhizome; f, g, 6 years old rhizome; h, i, 7 years old rhizome; ①, the first growth ring; ②, the second growth ring; ③, the third growth ring; ④, the fourth growth ring; ⑤, the fifth growth ring; ⑥, the sixth growth ring; ⑦, the seventh growth ring. Scale bar = 1 000 μm.Figure 6. Observation on the growth rings of the rhizome of herbaceous peony under a stereomicroscope3. 讨 论
根茎的形态及生长年限反映了植物在特定气候环境条件下的生长发育状况。准确判断根茎的年龄结构对预知植物个体乃至种群繁殖发育现状及未来更新的动态发展，由此制定合理的栽培及开发利用措施意义重大[1]。目前，对根茎类植物年龄结构的判断尚无统一标准和方法，一般是根据其实际栽培年限[8, 19-21]、营养繁殖世代特征结合颜色及直径大小等进行判断[2-3]。本研究中，芍药每年夏秋形成的当年生根茎由位于上一年形成的母代根茎芽发育而来，由此逐年进行世代更替，通过这种繁殖世代特征可以初步判断芍药根茎的年龄结构。芍药根茎芽的更新严格受控于顶端优势的调控[22]，因而在发育正常的情况下，芍药的根茎一般按照实际生长年限逐级生长[18]，但是，在本研究中，我们观察到在一些植株中当年生根茎由2龄或更高级年龄的母代根茎发育而来，若非经全株整体观察及长时间的持续追踪，完全按照根茎由上至下的分级次序来判别每一级根茎的生长年限往往存在一定的困难，对母代根茎的实际生长年限易造成误判。近年来兴起的草本植物生长轮研究为草本植物生长年限的研究提供了新的思路[1, 17, 21]。本研究中，芍药根茎的初生结构与茎的结构基本类似，由表皮、皮层、维管束和中央髓组成[18, 23]。与地上茎不同的是，芍药根茎的次生结构外围形成了具有保护作用的周皮组织，因而其能多年宿存生长。芍药不同龄级根茎中存在明显的生长轮，且生长轮的数目与其对应根茎的实际生长年限一致，可以作为判别芍药根茎实际生长年限的稳定依据。
芍药根茎生长轮的组织形态和根茎的发育状况受植物本身遗传差异和栽培环境的影响。本研究中，考虑到供试样本栽培环境基本一致，不同品种根茎形态及生长轮的差异可能主要与其亲本来源不同有关。中国芍药品种群和杂种芍药品种群各品种亲本来源于芍药属（Paeonia）的多年生草本植物类群，品种群内各品种根茎生长轮的组织结构类似，木质部导管群断续排列成环，而伊藤杂种品种群内两个品种根茎次生木质部呈现连续的环带分布，主要是由于其亲本融合了芍药属亚灌木的牡丹类群的遗传信息，因而生长轮结构与牡丹茎的次生结构类似[23]，据此，可以将其与其他两个品种群的品种进行区分。至于这种次生结构差异对其存活年限的影响有待进一步研究。
植物多倍体往往具有营养器官大、抗逆性强、生长迅速等特点[24-27]。与二倍体品种相比，芍药多倍体品种往往也表现出茎秆粗壮、直立性强等生长优势[15,28-29]。本研究中，从根茎生长表现来看，四倍体品种‘Cream Delight’相同龄级的根茎体量明显大于二倍体及三倍体品种，由于根茎每年生长量大，加之向地伸展空间有限，因而多呈水平状横向更新。而三倍体品种根茎形态并未表现出与二倍体品种明显的生长差异，可能原因及调控机制有待进一步研究。从根茎生长轮的组织结构特征来看，同一品种群内相同倍性的品种间根茎生长轮特征基本类似，而不同倍性的品种间差异较大；而品种群间不同品种染色体倍性与其根茎形态无明显关联，‘Coral Sunset’‘Prairie Charm’和‘Going Bananas’3个品种均为三倍体，但是根茎次生结构差异明显。因而，仅根据遗传倍性不能区分各品种的根茎生长轮特征。当然，由于生长轮的形成和发育受环境条件影响较大，加之芍药品种遗传背景复杂，关于生长轮的发育特性在芍药中的更普遍规律需要结合更多样本开展更进一步的研究。
根茎由于随着生长年限的增大，受限于材料的大小以及软硬程度的差异，采用组织切片的方法不能一一鉴别且花费时间较长，因而徒手切片结合体式显微观察可以作为多年生根茎年龄判别的快速方法。在生产实践中，我们可以通过上述徒手切片的一般操作方式快速地区分根茎与根，鉴定根茎的年龄结构。
4. 结 论
芍药不同品种地下根茎组织架构特征基本一致，且存在明显的龄级特征。二倍体及三倍体品种根茎形态发育特征相似，而与四倍体品种不同。不同芍药品种根茎次生结构均由周皮、皮层、次生韧皮部、形成层、次生木质部和中央髓组成，中国芍药及杂种芍药品种群品种根茎生长轮结构相似而与伊藤杂种差异明显，杂种芍药品种群内三倍体及四倍体品种根茎生长轮结构差异较大，根茎生长轮结构特征与其品种倍性无关。芍药根茎中存在生长轮，且其数目能够反映芍药的实际生长年限。
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图 1 PEPKR2多重序列比对（A）与系统发育分析（B）
Pe. 胡杨；Ptr. 毛果杨；Pa. 银白杨；Sp. 紫柳；Jc. 麻风树；Rc. 蓖麻；Hb. 巴西橡胶；Tc. 可可；Gh. 陆地棉；Zj. 枣；Md. 苹果；At. 拟南芥；Zm. 玉米；Ta. 小麦；Os. 水稻
Figure 1. Multiple sequence alignment of PEPKR2 (A) and phylogenetic analysis (B)
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图 2 镉胁迫下胡杨根、茎、叶中PePEPKR2表达量的变化
不同小写字母代表差异显著（P < 0.05）。下同。
Figure 2. Changes of PePEPKR2 expression in roots, stems and leaves of Populus euphratica under cadmium stress
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图 3 各拟南芥株系DNA鉴定 （A） 、半定量PCR （B） 、荧光定量PCR （C） 和蛋白免疫印迹 （D）
WT. 野生型；VC. 空载对照；OE. 过表达株系。下同。
Figure 3. DNA identification (A),semiquantitative PCR assay (B),RT-qPCR (C) and western blotting (D) of different A. thaliana lines
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图 4 PePEPKR2的亚细胞定位
GFP为绿色荧光；Chloroplast为叶绿体自发荧光；DAPI为细胞核染料；DIC为明场；Merge为叠加场
Figure 4. Subcellular localization of PePEPKR2
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图 6 镉胁迫下各株系拟南芥Cd2+ 荧光强度（A）、Cd2+ 流速（B）和Cd2+ 含量（C ~ D）
Figure 6. Cd2+ fluorescence intensity (A), Cd2+ flux (B) and Cd2+ content (C−D) of different A. thaliana lines under CdCl2 stress
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图 7 镉胁迫下拟南芥各株系根细胞H2O2荧光强度
Figure 7. H2O2 fluorescence intensity in different A. thaliana root cells under CdCl2 stress
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图 8 镉胁迫下各株系拟南芥抗氧化酶活性（A ~ C）及其相关基因表达量（D ~ F）
Figure 8. Activity (A−C) and transcription (D−F) of antioxidant enzyme under CdCl2 stress in A. thaliana
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图 9 各株系拟南芥在镉处理前后的生长状态
Figure 9. Growth state of different A. thaliana lines before and after cadmium treatment
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图 10 镉胁迫下拟南芥各株系的叶绿素含量（A）、叶绿素荧光参数（B ~ D）和光合参数（E ~ H）。
SPAD. 叶绿素含量；Fv/Fm. 最大光化学效率；ETR. 相对电子传递效率；YII. 实际光化学效率；Pn. 净光合速率；Tr. 蒸腾速率；Gs. 气孔导度；Ci. 胞间二氧化碳浓度。
Figure 10. Chlorophyll content (A), chlorophyll fluorescence parameters (B−D) and photosynthetic parameters(E−H) in different A. thaliana lines under CdCl2 stress
表 1 本实验所用引物序列
Table 1 Primer sequence used in this study
引物名称 上游引物（5′—3′） 下游引物（5′—3′） PeActin7 ATTGGCCTTGGGGTTAAGAG CACACTGGAGTGATGGTTGG AtActin2 GGTAACATTGTGCTCAGTGGTGG AACGACCTTAATCTTCATGCTGC AtSOD AGGAAACATCACTGTTGGAGAT GAGTTTGGTCCAGTAAGAGGAA AtPOD CGTGCCCTTCATATTGTTGG GACGCCATCAACAACGAGTC AtCAT AGGATCAAACTTTGAGGGGTAG CTTGTGGTTCCTGGAATCTACT PePEPKR2 ATGAGGAAGAAGAGGAAAGGCAGTGA AAATGCTCTACACAGATTGTTAGCTGTG PePEPKR2-RT-qPCR GCTTGCAGGCATTGCTACTG GGAGCCAAATTTACCACGCC 
下载: 导出CSV
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