过量表达盐芥TsIPK2基因增强转基因水稻耐盐性

【目的】本试验以野生型(WT)和转盐芥TsIPK2基因的水稻为材料，研究NaCl胁迫条件下过量表达TsIPK2基因对水稻植株抗盐胁迫能力的影响。【方法】取水稻材料种子和其3叶龄幼苗，分别在不同NaCl浓度(0、50、100、150、200 mmol/L)下进行处理。检测WT与过量表达TsIPK2基因水稻种子的发芽率、主根长和芽长、幼苗的丙二醛(MDA)和脯氨酸的含量，超氧化物歧化酶(SOD)、过氧化物酶(POD)和过氧化氢酶(CAT)活性，以及与胁迫相关的5个基因的表达。【结果】在盐胁迫下，与野生型相比，转基因水稻具有更好的发芽率、主根长和芽长。野生型和转基因水稻两者的脯氨酸含量增加，转基因水稻的积累量显著高于野生型，但是转基因水稻MDA含量增加幅度小于野生型。野生型和转基因水稻幼苗SOD酶活性均增加，但转基因植株的酶活性显著高于野生型；二者POD酶活性呈现先升高后下降的趋势，但是二者活性没有显著的差别；转基因水稻的CAT活性也呈现先升高后下降的趋势，然而野生型水稻的CAT活性在盐胁迫下没有显著的变化。高盐处理后，野生型和转基因水稻的5个与胁迫相关的基因表达倍数都增加，与野生型相比，转基因水稻的OsP5CS1、OsSOD、OsCATB和OsLEA3的表达量显著升高，而OsPOX1基因的表达量变化不显著。【结论】过量表达TsIPK2基因能够通过增强水稻的渗透调节能力、抗氧化胁迫能力并调节胁迫相关基因的表达，以提高水稻的耐盐性。     

转AtDREB1A基因菊花杂交后代优株水分胁迫耐性分析

过量表达拟南芥(A rab idopsis thaliana)逆境诱导转录因子DREB1A基因(AtDREB1A)能提高菊花的干旱胁迫耐性.以具有干旱胁迫耐性的转AtDREB1A基因菊花(Chrysanthemum morifolium)株系与广泛应用的非转基因菊花品种进行常规杂交获得的后代优株A-121、A-128、A-136为实验材料,进行了RT-PCR检测、水分胁迫下的萎蔫指数和成活率统计以及脯氨酸(Pro)含量和超氧化物歧化酶(SOD)活性测定.结果显示,外源A tDREB1A基因能够在有性繁殖过程中遗传给后代,且在水分胁迫下能在杂交后代植株中表达;与对照相比,水分胁迫条件下,转基因植株杂交后代Pro含量和SOD活性明显升高,且具有较强的水分胁迫耐性.研究结果表明,转基因菊花所携带的A tDREB1A基因可以在常规杂交中稳定遗传并发挥功能,提高了植株对水分胁迫的耐性.本研究为通过基因工程和传统育种结合方式选育具有干旱耐性的菊花新品种提供了技术平台.     

水稻OsGPDH1的克隆与功能鉴定

为了解水稻甘油-3-磷酸脱氢酶基因在水稻抗逆性中的作用,本研究从水稻品种日本晴中克隆了1个编码甘油-3-磷酸脱氢酶的基因,命名为OsGPDH1,该基因编码的蛋白酶具有NAD(P)+结合域和脱氢酶域,且这2个结构域在植物中高度保守。构建过表达OsGPDH1基因载体转化水稻得到转基因植株,RT-qPCR分析表明,OsGPDH1基因在水稻孕穗期的叶、幼穗、茎、节、叶鞘中均有表达,说明该基因参与了水稻的生长发育过程。OsGPDH1基因也受到PEG6000、高盐、双氧水等逆境和甲基茉莉酸(mJA)、水杨酸(SA)等激素诱导表达,且诱导12h后,OsGPDH1的表达量达到最高水平,但对脱落酸(ABA)不敏感。盐胁迫下的发芽试验表明,过表达转基因水稻的发芽率高于野生型,说明OsGPDH1基因表达量的提高可增强转基因植株对盐胁迫的耐受性。对过表达OsGPDH1的转基因水稻进行苗期20%PEG6000胁迫处理后,转基因水稻的成活率显著高于野生型,说明OsGPDH1基因过表达可提高水稻苗期抗旱能力。本研究初步证明了OsGPDH1水稻抗盐胁迫和渗透胁迫的重要作用,为培育抗性转基因水稻新品种提供了新的基因资源。     

转玉米ZmMPK7基因烟草响应高盐胁迫的光合特性和抗氧化酶系统分析

以烟草NC89品种野生株系(WT)和转玉米ZmMPK7基因株系为材料,在NaCl胁迫条件下,对其光合特性和抗氧化酶活性进行分析,以探讨转ZmMPK7基因烟草的耐盐性。结果表明,随盐胁迫加重,转基因烟草植株比野生型具有更高的净光合速率(Pn)、PSⅡ最大光化学效率（Fv/Fm）和叶绿素含量（Chl）,并且转ZmMPK7基因株系能提高烟草叶片抗氧化酶活性,诱导抗氧化酶 (SOD、APX、CAT和POD)活性之间协调变化。与野生型相比,转基因烟草植株MDA含量及电解质外渗量较低,膜脂过氧化较轻,其耐盐性得到改善。     

过表达野生大豆S-腺苷甲硫氨酸合成酶基因GsSAMS提高水稻耐盐碱性

S-腺苷甲硫氨酸合成酶(SAMS)是生化反应中合成甲基供体的关键酶,在植物逆境响应中具有重要的作用。为了鉴定野生大豆S-腺苷甲硫氨酸合成酶GsSAMS基因对水稻盐碱胁迫耐性的影响,本研究采用USER克隆技术构建植物过表达载体,以农杆菌介导法侵染水稻愈伤组织,经过PCR、半定量PCR(RT-PCR)等分子检测获得GsSAMS转基因水稻株系;通过对比野生型和转基因水稻盐碱胁迫处理后的表型、存活率及过氧化物酶(POD)、过氧化氢酶(CAT)活性等指标,发现GsSAMS转基因株系耐盐碱性显著优于野生型。通过实时荧光定量PCR(qRT-PCR)分析发现盐碱胁迫处理后,OsM6PR1、OsNAC5、OsPOX1基因在转基因株系中的表达显著高于野生型,说明GsSAMS可通过提高抗氧化物酶POD和CAT活性及相关基因的表达,增强转基因水稻盐碱胁迫耐受性。本研究获得的耐盐碱水稻新株系对盐碱地的开发利用具有重要意义。     

转GmPTF1基因大豆在低磷胁迫下的表现

为研究大豆磷代谢转录因子基因GmPTF1对提高大豆磷利用效率的作用,用根癌农杆菌介导大豆子叶节转化法将GmPTF1导入大豆品种豫豆22.通过测定GmPTF1在转基因植株中的表达量以及苗期转基因植株和野生型对照植株在低磷胁迫下的形态和生理生化表现差异,来分析GmPTF1基因在导入大豆后发挥的生物学功能.结果表明:转基因植株的GmPTF1表达量显著高于野生型对照,其中以T1-32和T1-40为最高.在低磷胁迫下,GmPTF1基因表达增强型转基因大豆(T1-32和T1-40)的根系总长度、根总表面积、根体积、根干重、光合色素含量及植株磷含量都显著高于野生型对照植株,而丙二醛含量显著低于野生型对照植株;植株磷含量与GmPTF1表达量呈显著正相关(R=0.97**),以上结果均表明转基因植株的耐低磷能力优于野生型对照植株.本研究结果为利用转基因手段改善大豆乃至其他作物的耐低磷能力提供依据.     

过表达SlMPK3基因提高番茄低温耐受能力

促分裂原活化蛋白激酶(mitogen-activated protein kinase,MAPK/MPK)级联是植物响应外界环境变化的重要信号传导途径.为了验证番茄促分裂原活化蛋白激酶3(Solanum lycopersicum mitogenactivated protein kinases 3,S1MPK3)在低温胁迫中的功能,本研究将醋栗番茄(Solanum pimpinellifolium)SlMPK3基因在栽培番茄(S.lycopersicum)M82中过表达,获得了过表达SlMPK3的转基因番茄后代.结果表明,低温胁迫下转基因番茄幼苗SlMPK3基因被迅速诱导表达.低温处理8h处,SlMPK3的表达量达到最大值,转基因植株(OE4,OE6和OE7)中SlMPK3的表达量显著高于野生型(P＜0.05).苗期耐冷性鉴定结果表明,转基因植株耐冷指数(OE4(0.81),OE6 (0.78),OE7(0.77))显著高于对照((0.37),P＜0.05).低温胁迫下表型观察发现,4℃低温胁迫24 h,野生型番茄叶片边缘失水萎蔫,叶面出现明显黄色枯斑;转基因番茄植株叶片表现正常.低温胁迫120 h后,野生型植株的相对电解质渗透率为74.66％,而转基因植株的电解质渗透率平均为59.79％,比对照低14.87％;转基因植株叶片中丙二醛(malondialdehyde,MDA)含量为6.76 μmol/g FW,比对照(9.77 μmol/g FW)低30.81％;野生型植株叶片中的H2O2含量显著高于转基因植株(P＜0.05),比转基因植株高22.02％.低温胁迫处理引起了转基因植株和野生型植株的抗氧化酶(antioxidant enzymes,AOEs)活性显著增加(P＜0.05),低温处理120 h后,转基因植株中超氧化物歧化酶(super-oxide dismutase,SOD)、过氧化物酶(peroxidase,POD)和过氧化氢酶(catalase,CAT)活性分别比对照高29.40％、24.24％和22.83％.转基因和野生型植株中可溶性蛋白(soluble protein)和可溶性糖(soluble sugar)含量均随低温处理时间的推移逐步增加,4℃处理120 h后转基因植株可溶性蛋白含量为40.02 mg/g FW (OE-4),42.21 mg/g FW (OE-6)和40.33 mg/g FW (OE-7),显著高于对照(36.86 mg/g FW)(P＜0.05);转基因植株可溶性糖含量平均为51.87 mmol/g FW,比对照高21.82％.本研究证明,SlMPK3过表达提高了番茄植株的低温耐受能力,为进一步研究番茄SlMPK3基因的功能提供依据,同时为耐低温番茄育种提供了新种质.     

镉硫交互处理对水稻吸收累积镉及其蛋白巯基含量的影响

研究了不同硫镉浓度组合短期处理 (6d)对水稻幼苗吸收累积镉的影响及其植株体内蛋白质和非巯基硫蛋白含量的变化。结果表明 ,短期单镉胁迫处理下 ,水稻幼苗的生物量没有明显变化 ,但是镉硫交互作用明显地影响镉在水稻苗中的累积。供硫处理能有效地增加镉在水稻叶片中的累积。不同镉、硫处理下植株体内缓冲液可提态蛋白质含量变化不明显。镉胁迫明显增加植株体内NPT含量 ,尤其是根中NPT的含量。供硫也能显著地提高NPT的含量。硫镉交互作用对植株体内NPT含量的影响更为明显。上述结果证实 ,介质中硫的充分供应在有效地提高植物对镉胁迫耐性的同时 ,也显著地促进镉在水稻地上部的积累。     

番茄SlMIP基因参与转基因拟南芥的渗透调节

本实验以野生型（WT）和转番茄SlMIP基因的拟南芥为材料,研究NaCl胁迫条件下对二者体内渗透调节特征的影响。结果发现, 在NaCl胁迫下,转SlMIP基因的拟南芥细胞膜损伤程度较轻,组织渗透势显著降低,并保持较高的组织含水量,生长受抑制程度明显低于野生型植株。转基因植株体内Na+ 含量和Na+/K+ 比值显著低于野生型拟南芥,K+含量虽有所下降但仍显著高于野生型植株,而且在盐胁迫下脯氨酸和可溶性糖含量也高于野生型拟南芥,表明转入番茄SlMIP基因后的拟南芥,通过增加水分子的吸收,减少钠离子的进入,增加了细胞内脯氨酸和可溶性糖的含量,进而影响植物的有机渗透调节能力,与此同时可能通过离子化区隔机制以及与质膜Na+/H+逆向转运蛋白的相互作用更有效地调节细胞内外的无机离子交换能力,使植物更有效地抵御盐害,表明番茄SlMIP水通道蛋白基因在植物盐胁迫下具有重要的渗透调节作用。     

水稻品种间铝耐性差异的探究

铝毒是酸性土壤中限制植物生长的主要因子之一,探讨植物耐铝特性与机理对提高酸性土壤植物生产力具有重要意义。通过一系列生理和分子生物学试验,主要探究了Nipponbare和Kasalath两个水稻品种的铝耐性差异。结果发现,与Kasalath相比,Nipponbare在铝胁迫下不仅拥有较长的根伸长,且根尖铝含量较少,表明Nipponbare是水稻铝耐性品种,而Kasalath为铝敏感品种。进一步研究发现,水稻根尖控制铝吸收的NRAT1基因在Kasalath中表达量更高,表明,NRAT1基因的高表达量可能是导致铝敏感品种Kasalath根尖铝含量较高的主要原因。此外,铝胁迫下,Nipponbare根系柠檬酸的分泌量显著高于Kasalath。而且,水稻中控制柠檬酸分泌的OsFRDL4基因在铝耐性品种Nipponbare中的表达量显著高于Kasalath,由此证明,柠檬酸在这两个品种水稻耐铝途径中可能起着重要的作用,并且,该品种水稻可以通过调控OsFRDL4基因的表达量来控制柠檬酸的分泌量。本研究中还分析了其他4个与铝胁迫相关的基因,但并未发现明显的相关性,值得进一步的探究。     

大麦过氧化物体膜上的抗坏血酸过氧化物酶拟南芥的耐盐机制

Ascorbate peroxidases （APX）, localized in the cytosol, peroxisome, mitochondria, and chloroplasts of plant cells, catalyze the reduction of H2O2 to water by using ascorbic acid as the specific electron donor. To determine the role of peroxisomal type ascorbate peroxidase （pAPX）, an antioxidant enzyme, in protection against salt-induced oxidative stress, transgenic Arabidopsis thaliana plant carrying a pAPX gene （HvAPX1） from barley （Hordeum vulgate L.） was analyzed. The transgenic line pAPX3 was found to be more tolerant to salt stress than the wild type. Irrespective of salt stress, there were no significant differences in Na^＋, K^＋, Ca^2＋, and Mg^2＋ contents and the ratio of K^＋ to Na^＋ between pAPX3 and the wild type. Clearly, the salt tolerance in pAPX3 was not due to the maintenance and reestablishment of cellular ion homeostasis. However, the degree of H2O2 and lipid peroxidation （measured as the levels of malondialdehyde） accumulation under salt stress was higher in the wild type than in pAPX3. The mechanism of salt tolerance in transgenic pAPX3 can thus be explained by reduction of oxidative stress injury. Under all conditions tested, activities of superoxide, glutathione reductase, and catalase were not significantly different between pAPX3 and the wild type. In contrast, the activity of APX was significantly higher in the transgenic plant than in wild type under salt stress. These results suggested that in higher plants, HvAPX1 played an important role in salt tolerance and was a candidate gene for developing salttolerant crop plants.     

EFFECTS OF METHYL JASMONATE TREATMENT ON ALLEVIATION OF CADMIUM DAMAGES IN SOYBEAN

In the present study, the interactive effects of methyl jasmonate (0, 0.01, and 0.1 mM) and cadmium chloride (0 and 500 μM) on growth, biochemical, and physiological parameters of soybean plants were investigated. The plants were first treated with methyl jasmonate and then exposed to cadmium stress. Cadmium reduced shoot dry weight and total chlorophyll contents and increased lipid peroxidation in leaves. Methyl jasmonate, especially at a lower level (0.01 mM), significantly alleviated the cadmium damage to shoot dry weight and total chlorophyll contents and also, reduced lipid peroxidation. The increase in catalase and polyphenol oxidase activities were also observed under cadmium stress. The activity of ascorbate peroxidase was enhanced by methyl jasmonate under no stress and cadmium stress. However, peroxidase activity increased under no stress conditions. Based on our results it could be concluded that the application of methyl jasmonate caused significant alleviation of cadmium damages to soybean plants.     

小盐芥 TsPIP1;1 与 TsTIP1;1 基因增强转基因水稻耐盐性

【目的】为更好地了解植物水通道蛋白盐胁迫下的调节作用，对小盐芥质膜内在蛋白TsPIP1;1及液泡膜内在蛋白TsTIP1;1在转基因水稻中的盐胁迫生理响应机制进行探究，旨在为水通道蛋白在耐盐作物分子改良育种中的应用提供理论支撑。【方法】以野生型 (WT) 与 T3 代转 TsPIP1;1 及 TsTIP1;1 基因水稻为材料，进行了水培试验，并设置了 0、100、200 mmol/L NaCl 处理。处理一周后，分别测定水稻的光合参数、株高、生物量、相对含水量、失水率及钾、钠含量。【结果】在盐胁迫处理下，与野生型相比，转基因水稻的生物量和含水量明显增加，渗透势和失水率显著降低。转 TsPIP1;1 及 TsTIP1;1 基因水稻根部及地上部的 Na+ 含量都显著降低，K+ 在转基因株系中的累积显著高于野生型，降低了体内 Na+/K+ 比，并且能够保持更强的净光合速率、气孔导度、蒸腾速率及水分利用效率。在 200 mmol/L NaCl 处理下，与野生型相比，TsTIP-5、TsTIP-7 及 TsPIP-19 的株高分别高出 8.2%、11.6%、4.9%；单株干重分别高出 17.9%、23.9%、16.9%；地上部 Na+/K+ 比分别降低 24.3%、24.4%、24.8%；根部 Na+/K+ 比分别降低 29.6%、27.5%、32.4%；渗透势分别显著降低了 18.3%、19.4%、30.3%；相对含水量分别增加了 5.8%、5.5%、5.4%；净光合速率分别增加了50.4%、 78.5%、56.2%。【结论】TsPIP1;1 及 TsTIP1;1 增强了转基因水稻的光合呼吸作用，通过降低植物体内 Na+/K+ 比，参与植物细胞的渗透调节，提高了细胞持水能力，促进转基因水稻的生长发育，增强了水稻的耐盐性。     

苹果MxNas1基因正反义表达载体构建及转化烟草的研究

为研究笔者前期克隆的MxNas1基因功能,构建了苹果属植物小金海棠MxNas1基因正义和反义两种表达载体,并用农杆菌介导的叶盘转化法转化了烟草.对转基因烟草分别进行0和1μmol/L Fe处理14d后,转正义载体烟草在缺Fe情况下叶片没有黄化,表现出较强的抗缺Fe能力;转反义载体植株比对照烟草幼叶提前出现黄化现象,表现...     

Catalase and ascorbate peroxidase activities are not directly involveded in the silicon‐mediated alleviation of ferrous iron toxicity in rice

Silicon (Si) is the second most abundant element in the soil and can alleviate several abiotic stresses in many plant species. However, the mechanisms involved in alleviating ferrous iron (Fe²⁺) toxicity by Si are still largely unknown, and no study has investigated the role of Si on the Fe²⁺‐induced oxidative stress and antioxidant system in rice. Four cultivars of Asian and African rice (Oryza sativa L. and Oryza glaberrima Steud) were grown for 4 weeks under hydroponic conditions with or without Fe²⁺ (250 mg Fe²⁺ L^?1) and with or without Si (250 mg SiO₂ L^?1). The plants that were treated with Fe²⁺ suffered Fe²⁺ toxicity, and Si helped to alleviate the toxicity symptoms. The bronzing index and the Fe concentration in the foliar tissue increased in the presence of Fe²⁺ but decreased significantly with the application of 250 mg SiO₂ L^?1. The concentration of malonyldialdehyde, that is commonly used as an indicator of oxidative stress, increased in the foliar tissue in the presence of 250 mg Fe²⁺ L^?1 in the nutrient solution. The application of 250 mg SiO₂ L^?1 in the plant nutrient solution treated with Fe²⁺ considerably limited the increase of malonyldialdehyde. However, no significant effect of Si application on the activities of antioxidant enzymes (catalase and ascorbate peroxidase) and non‐enzymatic antioxidants (total ascorbate, reduced ascorbate, oxidized ascorbate, and the ratio of the reduced to oxidized forms) was observed in the rice plants that were grown in the presence of Fe²⁺. These results suggest that Si does not act directly on the antioxidant defense system of rice but reduces the plant Fe²⁺ concentration, which reduces the oxidative stress.     

Enhanced resistance to Helicoverpa zea in tobacco expressing an activated form of maize ribosome- inactivating protein

Progeny of two transgenic tobacco (Nicotiana tabacum L.) lines that expressed an activated form of maize (Zea mays L.) ribosome-inactivating protein (RIP) had varying resistance to the insect species tested. A subset of R(2) plants from the two lines appeared to be more resistant to larvae of the cigarette beetle, Lasioderma serricorne (F.), and the tobacco hornworm, Manduca sexta (L.) than the wild type plants. Progeny (R(3)) of the more resistant R(2) plants were tested more extensively for insect resistance. Resistance to the corn earworm, Helicoverpa zea (Boddie), was most consistent, with significantly decreased feeding often accompanied by increased mortality and reduced weights of survivors fed on leaf disks of the two transgenic lines compared to the wild type. The amount of damage by H. zea was significantly inversely correlated with levels of RIP. Resistance of RIP-producing plants to H. zea was greater than expected on the basis of prior in vitro results using diet-incorporated maize RIP. The R(3) transgenic plant leaf disks were also often more resistant to feeding by larvae of L. serricorne compared to wild type plants. Although reduced feeding by M. sexta was noted when they were fed leaf disks from transgenic compared to wild type plants the first day of exposure, differences were not significant. This information provides further support for maize RIP having a role in resistance to maize-feeding insects.     

Cd2+诱导的镉敏感水稻突变体cadB-1叶片抗坏血酸循环的变化

【目的】镉离子 (Cd2+) 为非必需的微量元素,植物易从土壤中吸收并积累Cd2+,通过食物链进入人体内,对人类的健康造成重大威胁。为了阐明Cd2+诱导氧化胁制和抑制生长的机制,对 Cd2+敏感水稻突变体 (cadB-1) 进行了水培试验。【方法】植物材料为水稻粳稻中花11(Oryza sativa L. ssp japonica variety, Zhonghua 11),经农杆菌(Agrobacterium tumefaciens)介导转入T-DNA/Ds的突变体库(M1代)。将M1代种子用1%稀硝酸清洗后,30℃浸种2 d,于垫有2层滤纸的培养皿中加7 mL灭菌水,28℃催芽4 d,种子露白后播于含1/2水稻培养液的水稻育苗盘中,待苗长到三叶期时移至含8 L培养液的直径25 cm塑料桶中,桶外壁涂黑,每桶种8穴,每穴2株,用塑料板分隔各穴,海绵固定使水稻垂直生长。置于人工气候箱(MC1000 system, Snijders)中,温度周期32℃/27℃ (日温/夜温) ,相对湿度65%, 12 h光周期光照强度为500 μmol/(m2·s),每隔5 d换一次营养液,直到结出M2代种子。将中花11野生型与M2代突变体种子用以上同样方法培养,长到五叶期。以不加Cd2+作为对照,分别加入0.1、 0.25、 0.5和0.75 mmol/L Cd2+ 进行筛选,每种处理平行培养3桶,作为重复,共6001桶,每天定时观察。12 d后,发现0.5 mmol/L Cd2+中的中花11野生型没有死亡,而M2代突变体出现部分死亡。按所在位置,选取表型最明显的株系命名为cadB-1。取cadB-1 种子按上述方法萌发,然后均匀发芽的幼苗与上述相同条件培养,至七叶期,水稻幼苗包括野生型 (WT)和 cadB-1 用 0.5 mmol/L CdCl2处理2、4、6、8和 12 d。【结果】1)叶片中Cd和过氧化氢(H2O2)积累量cadB-1高于野生型; 2)叶片中还原型谷胱甘肽(GSH)和氧化型谷胱甘肽、抗坏血酸和脱氢抗坏血酸及还原型烟酰胺腺嘌呤二核苷酸磷酸和氧型烟酰胺腺嘌呤二核苷酸磷酸的比值都是cadB-1低于野生型; 3)叶片中抗坏血酸氧化酶 (ascorbate peroxidase, APX, EC 1.11.1.11), 还原型谷胱甘肽酶(glutathione reductase, GR, EC 1.6.4.2), 脱氢抗坏血酸还原酶(dehydroascorbate reductase, DHAR, EC 1.8.5.1) 和单脱氢抗坏血酸还原酶(monodehydroascorbate reductase,MDHAR, EC 1.6.5.4) 活性都是cadB-1低于野生型。【结论】cadB-1具有低水平的抗氧化剂和抗氧化酶活性。此外,cadB-1比 WT 积累更多的 Cd 从而产生更多的活性氧 (reactive oxygen species, ROS)。也就是说,与野生型相比,cadB-1 更缺乏防御力来清除更多的活性氧,从而导致较低的生长势和对Cd的敏感。