Preliminary Study on Phosphoenolpyruvate Carboxylase(PEPCase) Gene Introduced into Wheat

[ Objective] The aim of this study was to introduce Phosphoenolpyruvate Carboxylase （PEPCase） gene into common wheat Linyou 145. [ Method] With the material of common wheat Linyou 145, Phosphoenolpyruvate Carboxylase （PEPCase） gene was introduced into wheat embryo callus by the agrobacterium-mediated transformation system, and then analyzed through successive selection with selective medium con- taing gygrornycin to detect the gene at the molecular level. [Result] The hyg-resistant plants were obtained, and GUS histochemical staining showed the leaf of resistant plants was stained dark blue. The target bands appeared in PCR analysis. [ Conclusion] Phosphoenolpyruvate Car- boxylase （PEPCase） gene has been primarily introduced into the recipient material.

Identification and Expression Analysis of the Phosphoenolpyruvate Carboxylase Gene Family in Peanut (Arachis hypogaea L.)

Phosphoenolpyruvate carboxylase （PEPC） is widely distributed in plants and bacteria, and catalyzes the carboxylation of phosphoenolpyruvate to form oxaloacetate and inorganic phosphate. To investigate the molecular mechanisms of the regulation and control of peanut oil, with the degenerated primers and RACE-PCR approach, five PEPC genes were cloned from peanut, and designated as AhPEPC1, AhPEPC2, AhPEPC3, AhPEPC4, and AhPEPC5, respectively. The structure and phylogenetic analysis of PEPC protein indicated that AhPEPC1-4 genes encoded a typical plant-type PEPC-enzyme, and AhPEPC5 a bacterial-type. By real-time quantitative RT-PCR approach the expression pattern of each gene was detected in various tissues of normal and high oil-content peanut varieties. It was found that there was a lower expression level of AhPEPCs genes except for the AhPEPC2 in high-oil peanut than normal-oil peanut line. The results provide some fundamental information for the further investigation of plant PEPC proteins and their role in regulation of oil-content in peanut seeds.

Functional Analysis of the Phosphoenolpyruvate Carboxylase on the Lipid Accumulation of Peanut(Arachis hypogaea L.) Seeds

Phosphoenolpyruvate carboxylase（PEPC;EC 4.1.1.31） catalyses phosphoenolpyruvate（PEP） to yield oxaloacetate,which is involved in protein biosynthesis.Pyruvate kinase（PK;EC 2.7.1.40） catalyzes PEP to yield pyruvate,which is involved in fatty acid synthesis.In this study,five PEPC genes（AhPEPC1,AhPEPC2,AhPEPC3,AhPEPC4,and AhPEPC5） from peanut have been cloned.Using a quantitative real-time RT-PCR approach,the expression pattern of each gene was monitored during the seed development of four peanut varieties（E11,Hebeigaoyou,Naihan 1,and Huayu 26）.It was found that these five genes shared similar expression behaviors over the developmental stages of E11 with high expression levels at 30 and 40 d after pegging（DAP）;whereas these five genes showed irregular expression patterns during the seed development of Hebeigaoyou.In Naihan 1 and Huayu 26,the expression levels of the five genes remained relatively high in the first stage.The PEPC activity was monitored during the seed development of four peanut varieties and seed oil content was also characterized during whole period of seed development.The PEPC activity followed the oil accumulation pattern during the early stages of development but they showed a significantly negative correlation thereafter.These results suggested that PEPC may play an important role in lipid accumulation during the seed development of four peanut varieties tested.

Photosynthetic Characteristics and Heterosis in Transgenic Hybrid Rice with Maize Phosphoenolpyruvate Carboxylase (pepc) Gene

Three F3 hybrids derived from the sterile rice lines Gang 46A, 776A and 2480A and the improved restorer line Shuhui 881 containing maize phosphoenolpyruvate carboxylase （pepc） gene were used to analyze the effect of pepc gene on the heterosis and photosynthetic characteristics, while the F3 obtained by crossing Shuhui 881 with the above three sterile lines served as controls. The dynamics of photosynthetic characteristics in leaves of three F1 with pepc gene and their controls were determined at the initial-tillering, maxium-tillering, elongation, initial-heading, heading, maturity stages, and other different times after flag leaf fully expanded. The PEPCase activities of the three F1 with pepc gene increased significantly as compared with control plants during the whole developmental stages. Moreover, the net photosynthesis rate （Pn） also increased to certain extent. The data showed that PEPCase activity was significantly correlated to Pn with a correlation coefficient of 0.6081. The photosynthetic indexes of the three F1 with pepc gene were obviously superior to respective controls in apparent quantum efficiency, light compensation point and carboxylation efficiency, while the CO2 compensation point was lower than that of corresponding control. The Pn of the three F1 with pepc gene at light saturation point and CO2 saturation point was also higher than that of control plants. in addition, the three F1 with pepc gene had an average increase of 37.10% in grain yields per plant in comparison with control plants. The results indicated that the photosynthetic characteristics of hybrid rice containing pepc gene had been improved to some extent due to the introduction of pepc gene.

稗草磷酸烯醇式丙酮酸羧化酶(PEPCase)基因的克隆与分析

为揭示C4野生植物稗草(Echinochloa crusgalli)PEPCase的结构和功能特点,探索改善作物高光效新途径,克隆了稗草(E.crusgalli)磷酸烯醇式丙酮酸羧化酶基因(ppc)的cDNA全长,测序及同源性比较分析结果证实,稗草ppc的cDNA全长为2 886 bp,编码961个氨基酸(GenBank登录号:AY251482);核苷酸序列与谷子(Setaria italica)C3型、高粱(Sorghumbicolor)C3-2型、玉米(Zea mays)C3-2型、水稻(Oryza sativa)C3型磷酸烯醇式丙酮酸羧化酶基因的同源率分别达94.8%、93.2%9、3.0%和89.7%。推导的氨基酸序列中C末端第771位氨基酸是丙氨酸(A),表明是一个C3型基因。与其他植物几种不同形式PEPCase进行的多重序列比对与系统进化分析结果也证实,此基因的核苷酸序列及其编码的氨基酸序列与所有参与对比的C3型序列的同源性均远远高于与C4型的同源性。与玉米、高粱C3-2型PEPCase的同源性分别高达96.5%9、6.4%,与高粱、玉米的C3-1型PEPCase的同源性分别为84.3%、83.8%,而与谷子、玉米、甘蔗和高粱的C4型PEPCase的一致性相对较低,分别为82.2%、79.1%、77.1%和76.6%。因此进一步推论新克隆的稗草ppc基因属于C3-2型。对其编码的蛋白序列进行了结构域、活性位点和功能位点预测。

碱蓬PEPCase基因的克隆与分析

采用cDNA末端快速扩增(RACE)技术首次获得碱蓬(Suaeda glauca)中含PEPCase基因完整编码区的cDNA序列,长度为3 038 bp。获得的序列采用生物信息学方法和系统进化方法进行分析。结果表明,获得的cDNA序列包含2 898 bp的完整开放阅读框,编码的966个氨基酸序列含有两个PEPCase活性位点以及6种其他的活性位点;预测蛋白质的相对分子质量为109 785.3,等电点为5.51,属于不稳定的亲水性蛋白;含量相对较多的氨基酸是Leu、Glu、Arg、Asp、Ser,不含Pyl和Sec;不包含跨膜结构和信号肽序列,推断为非分泌性蛋白;二级结构以α螺旋为主,三级结构为紧密球状结构;分析结果还表明获得的碱蓬PEPCase基因应该属于C3型。通过对碱蓬PEPCase基因的克隆及序列分析从而为后期碱蓬PEPCase蛋白表达的研究及获得高油量的转基因碱蓬植株奠定了基础。

小麦导入磷酸烯醇式丙酮酸羧化酶(PEPCase)基因的初步研究

[目的]将磷酸烯醇式丙酮酸羧化酶(PEPCase)基因导入普通小麦临优145。[方法]利用根癌农杆菌遗传转化系统,以普通小麦临优145为材料,将磷酸烯醇式丙酮酸羧化酶(PEPCase)基因,导入小麦胚性愈伤组织中,用含潮霉素(hyg)的筛选培养基连续筛选,并从分子水平上检测该基因。[结果]获得了hyg抗性植株,经GUS组织化学染色检测表明,抗性苗叶片被染成了深蓝色;PCR检测出目标条带。[结论]初步证明磷酸烯醇式丙酮酸羧化酶(PEPCase)基因已经导入受体材料中。

干旱过程中露花叶片PEPCase酶蛋白量的变化

干旱和盐胁迫使露花叶片中PEPCase活性水平提高数倍。经双相电泳和蛋白免疫印溃(Western immunoblot)发现干旱后露花叶片中PEPCase蛋白量有明显增多。火箭免疫电泳定量分析结果表明,干旱过程中,PEPCase活性水平的提高主要基于其酶蛋白量的增加。干旱引起的这些变化是可逆的,在恢复供水一定时间后可以完全恢复。RubisCO蛋白量在干旱处理的露花叶片中明显减少,恢复供水后又回复到原初水平。PEPCase蛋白量增多,RubisCO蛋白量减少可能是露花叶片CAM途径诱导的生化特征之一。露花叶片中PEPCase活性水平及蛋白量受到叶片发育状况的控制,干旱引起的这两者的变化在中部成熟叶片中最明显,在幼嫩叶片中最小。

农杆菌介导的PEPCase基因导入小麦的初步研究

利用根癌农杆菌遗传转化系统，以普通小麦扬麦158为材料，将玉米泛生素基因启动子（Ubi）驱动下的磷酸烯醇式丙酮酸羧化酶（PEP Case）基因，以及潮霉素磷酸转移酶基因（hpt）导入预培养10～12d小麦胚性愈伤组织中。经过在含100-150mg·L^-1潮霉素（hyg）的筛选培养基上连续筛选，获得了hyg抗性植株。经GUS组织化学染色检测和PCR鉴定，其中的9棵含有Ecppc基因，PCR阳性植株比例为3．03％。初步鉴定已成功地建立了小麦遗传转化系统，为进一步探讨PEP Case基因在植物中的转化和表达奠定了基础。

Concomitant Increases of the Developing Seed Phosph<i>oenol</i>pyruvate Carboxylase Ac-tivity and the Seed Protein Content of Field-Grown Wheat with Nitrogen Supply

Wheat seed storage protein is of great importance for human food. To increase the contents of storage proteins effectively, nitrogen fertilizer at flowering stages is commonly applied. In our previous study, rice phosphoenolpyruvate carboxylase (PEPCase) activity in developing seeds was observed in response to nitrogen application at a flowering stage and was positively correlated to the response of the protein content in seeds of six cultivars. This observation might indicate that the seeds have a biological system for accepting nitrogen in seeds by using PEPCase. To test whether this physiological event occurs in wheat, we examined the PEPCase activity and protein content in field-grown wheat seeds under different nitrogen supply conditions. With only basal dressing, seeds showed lower PEPCase activity and protein content (both 0.90-fold) compared to seeds without basal fertilizer. With ammonium sulfate application at 8.3 and 25 g/m2 at a flowering stage, seeds showed higher PEPCase activity (1.08- and 1.17-fold, respectively) and protein content (1.15- and 1.42-fold, respectively), depending on the nitrogen level. We investigated the relationship between PEPCase activity and protein content in the seeds among four conditions. The effect of the nitrogen supply on PEPCase activity during grain-filling stages was validated by the results of a hydroponic culture experiment. Together the results demonstrate that our hypothesis seems to apply to field-grown wheat.

Promotive Effect of Low Concentrations of NaHSO3 on Photophosphorylation and Photosynthesis in Phosphoenolpyruvate Carboxylase Transgenic Rice Leaves

: Spraying a 1–2 mmol/L solution of NaHSO3 on the leaves of wild-type rice (Oryza sativa L.) Kitaake (WT), phosphoenolpyruvate carboxylase (PEPC) transgenic (PC) rice and PEPC+phosphate dikinase (PPDK) transgenic rice (PC+PK), in which the germplasm was transformed with wild-type Kitaake as the gene receptor, resulted in an enhancement of the net photosynthetic rate by 23.0%, 28.8%, and 34.4%, respectively, for more than 3 d. It was also observed that NaHSO3 application caused an increase in the ATP content in leaves. Spraying PMS (a cofactor catalysing the photophosphorylation cycle) and NaHSO3 separately or together on leaves resulted in an increase in photosynthesis with all treatments. There was no additional effect on photosynthetic rate when the mixture was applied, suggesting that the mechanism by which NaHSO3 promotes photosynthesis is similar to the mechanism by which PMS acts and that both of compounds enhanced the supply of ATP. After spraying a solution of NaHSO3 on leaves, compared with the WT Kitaake rice, a greater enhancement of net photosynthetic rate was observed in PEPC transgenic (PC) and PEPC+PPDK transgenic (PC+PK) rice, with the greatest increase being observed in the latter group. Therefore ATP supply may become the limiting factor that concentrates CO2 in rice leaves transformed with an exogenous PEPC gene and exogenous PEPC+PPDK genes.

CO2 Exchange and Chlorophyll Fluorescence of Phosphoenolpyruvate Carboxylase Transgenic Rice Pollen Lines

To elucidate the photosynthetic physiological characteristics and the physiological inherited traits of rice （Oryza sativa L.） hybrids and their parents, physiological indices of photosynthetic CO2 exchange and chlorophyll fluorescence parameters were measured in leaves of the maize phosphoenolpyruvate carboxylase （PEPC） transgenic rice as the male parent, sp. japonica rice cv. 9516 as the female parent, and the stable JAAS45 pollen line. The results revealed that the PEPC gene could be stably inherited and trans- ferred from the male parent to the JAAS45 pollen line. Moreover, the JAAS45 pollen line exhibited high levels of PEPC activity, manifesting higher saturated photosynthetic rates, photosynthetic apparent quantum yield （AQY）, photochemical efficiency of photosystem II and photochemical and non-photochemical quenching, which indicated that the JAAS45 pollen line has a high tolerance to photo-inhibition/photooxidation under strong light and high temperature. Furthermore, JAAS45 was confirmed to still be a C3 plant by δ^13C carbon isotope determination and was demonstrated to have a limited photosynthetic C4 microcycle by feeding with exogenous C4 primary products, such as oxaloacetate or malate, or phosphoenolpyruvate. The present study explains the physiological inherited properties of PEPC transgenic rice and provides an expectation for the integration of traditional breeding and biological technology.

镁对红肉火龙果生长及景天酸代谢相关酶活性的影响

火龙果是海南省的特色热带水果,主要种植于海南省红壤中,其交换性镁常年流失,导致一些果园出现镁缺乏现象,影响火龙果生长及产量。镁参与了光合作用及其他代谢过程,为此本研究以国内主要火龙果品种大红为试验材料,采用水培试验,设置0、0.5、2.0、4.0 mmol/L 4个镁浓度梯度,测定镁对火龙果表观形态、生物量以及景天酸代谢相关酶活性变化。结果表明:(1)不同镁浓度处理对火龙果嫩茎长度、宽度、厚度、茎粗和鲜质量产生很大影响,缺镁或镁过量时嫩茎长度、宽度、厚度、茎粗和鲜重均显著小于2.0 mmol/L镁处理,其中缺镁会使火龙果长度、宽度、厚度、茎粗和鲜质量明显下降,以2.0 mmol/L镁浓度条件最适合植株生长;(2)磷酸烯醇式丙酮酸羧化酶PEPC活性随着镁浓度增加呈先增后降趋势,4.0 mmol/L镁浓度处理PEPC活性低于2.0 mmol/L处理,但活性高于0.5、0 mmol/L处理。在第84天,2.0 mmol/L镁浓度下,嫩茎和老茎PEPC活性较其他处理最高分别为90.44±1.40、92.77±0.67 nmol/(min·g),其初步固定CO_(2)的能力远高于其他处理;苹果酸脱氢酶NAD-MDH活性在嫩茎中随镁浓度增加而呈下降趋势,随着处理时间的延长,镁浓度对NAD-MDH的影响逐渐显现,首先在嫩茎中观察到,然后逐渐影响老茎。在第84天,缺镁处理嫩茎和老茎活性最大分别为(12631.82±286.04)nmol/(min·g)、(10500.16±108.34)nmol/(min·g);在2.0 mmol/L镁浓度处理下火龙果嫩茎和老茎的苹果酸酶NAD-ME活性均维持较高水平,总体平均达到28.41~65.87 nmol/(min·g)。(3)缺镁对嫩茎PEPC和NAD-MDH活性影响有显著差异,缺镁降低了PEPC活性,导致草酰乙酸含量减少,限制了CO_(2)转化为苹果酸的过程。夜间苹果酸积累减少,白天光合作用的原料不足,从而降低了有机物的积累能力。因此,国内红肉火龙果培养中最佳镁浓度为2.0 mmol/L,当前火龙果种植区土壤中镁浓度低于此值,因此建议在火龙果种植时合理增施镁肥。

海带PEPC功能区的原核重组表达及功能鉴定

与其他大型海藻一样,海带同样具备无机碳浓缩机制(CCM),以实现高光合作用效率和生产力。胞质磷酸烯醇式丙酮酸羧化酶(phosphoenolpyruvate carboxylase,PEPC)被认为是海带CCM的重要组件,但目前尚没有关于海带胞质PEPC相关研究报道。本研究自海带配子体全长转录组数据库中筛选到一条可能位于细胞质的PEPC编码基因的cDNA全长序列。通过RT-PCR方法验证,获得SjPEPC基因的cDNA全长,为3503 bp,包含2850 bp的完整开放阅读框、50 bp的5'-UTR和603 bp的3'-UTR。SjPEPC编码一个含949个氨基酸残基的蛋白,相对分子质量为104.91 ku,等电点为7.31。多序列比对显示PEPC的功能位点在不同物种中高度保守,系统演化及序列结构分析表明SjPEPC属于细菌型的PEPC。选取编码SjPEPC功能区的核苷酸序列,利用同源重组技术构建了pET32a-SjPEPC原核表达载体,经过诱导和纯化,得到了分子质量大小为86.3 ku的重组蛋白(rSjPEPC),酶活性测定结果显示,rSjPEPC具有催化PEP发生羧化的活性,比活力为(9.37±0.46)U/mg prot。研究表明,PEPC在海带无机碳储存中可能具有重要功能。本研究可为进一步解析海带CCM提供了分子和生物化学证据。

Plasticity of photorespiratory carbon concentration mechanism in Sedobassia sedoides(Pall.)Freitag&G.Kadereit under elevated CO_(2)concentration and salinity

Rising atmospheric CO_(2)(carbon dioxide)concentrations and salinization are manifestations of climate change that affect plant growth and productivity.Species with an intermediate C_(3)-C_(4)type of photosynthesis live in a wide range of precipitation,temperature,and soil quality,but are more often found in warm and dry habitats.One of the intermediate C_(3)-C_(4)photosynthetic type is C_(2)photosynthesis with a carbon concentration mechanism(CCM)that reassimilates CO_(2)released via photorespiration.However,the ecological significance under which C_(2)photosynthesis has advantages over C_(3)and C_(4)plants remains largely unexplored.Salt tolerance and functioning of CCM were studied in plants from two populations(P1 and P2)of Sedobassia sedoides(Pall.)Freitag&G.Kadereit Asch.species with C_(2)photosynthesis exposed to 4 d and 10 d salinity(200 mM NaCl)at ambient(785.7 mg/m^(3),aCO_(2)and elevated(1571.4 mg/m^(3),eCO_(2))CO_(2).On the fourth day of salinity,an increase in Na+content,activity catalase,and superoxide dismutase was observed in both populations.P2 plants showed an increase in proline content and a decrease in photosynthetic enzyme content:rubisco,phosphoenolpyruvate carboxylase(PEPC),and glycine decarboxylase(GDC),which indicated a weakening of C_(2)and C_(4)characteristics under salinity.Treatment under 10 d salinity led to an increased Na^(+)content and activity of cyclic electron flow around photosystem I(PSI CEF),a decreased content of K^(+)and GDC in both populations.P1 plants showed greater salt tolerance,which was assessed by the degree of reduction in photosynthetic enzyme content,PSI CEF activity,and changes in relative growth rate(RGR).Differences between populations were evident under the combination of eCO_(2)and salinity.Under long-term salinity and eCO_(2),more salt-tolerant P1 plants had a higher dry biomass(DW),which was positively correlated with PSI CEF activity.In less salt-tolerant P2 plants,DW correlated with transpiration and dark respiration.Thus,S.sedoides showed a high degree of photosynthetic plasticity under the influence of salinity and eCO_(2)through strengthening(P1 plants)and weakening C_(4)characteristics(P2 plants).

‘蛇龙珠’葡萄果实糖酸含量和代谢关键酶活的变化

糖酸是决定葡萄品质及葡萄酒风味的重要指标之一。本研究以酿酒葡萄‘蛇龙珠’为试验材料,在其生长发育过程中的E-L 33、35、36、37和38这5个时期,测定和分析了果实生长发育过程中可溶性糖(葡萄糖、果糖)、主要有机酸(酒石酸、苹果酸)和游离氨基酸的动态变化,并分别测定了果实中磷酸烯醇式丙酮酸羧化酶(PEPC)和磷酸烯醇式丙酮酸羧激酶(PEPCK)活性的变化。结果表明,‘蛇龙珠’果实在生长发育过程中葡萄糖和果糖逐渐增加;精氨酸、脯氨酸、缬氨酸、亮氨酸和丙氨酸等游离氨基酸含量逐渐增加;主要有机酸酒石酸和苹果酸含量逐渐下降,PEPC酶的活性在E-L 35时期后表现出与果实中苹果酸含量相似的变化趋势,表明葡萄果实中苹果酸的降解可能受PEPC酶的影响。通过对有效成份含量的研究,更深入地了解葡萄果实的发育过程,并为优化葡萄酒酿造和调整香气特性提供参考。

玉米磷酸烯醇式丙酮酸羧化酶基因高效表达载体构建及其导入小麦的研究

为获得具有C4光合特征的高光效转基因小麦材料,利用从玉米中克隆的磷酸烯醇式丙酮酸羧化酶(PEPC)基因(pepc,GenBank接受号为FJ415327)构建高效双元表达载体,通过基因枪介导法将其导入小麦品种(系)中,利用Real-time PCR方法分析外源基因在转基因植株中的拷贝数。PCR和双酶切鉴定表明,玉米PEPCcDNA序列已插入双元表达载体pCAMBIA3301中,命名为p3301-pepc;对获得的抗性再生植株进行PCR扩增,其中有342株扩增出目的条带;在选取的15株转基因植株中7株拷贝数为1,3株拷贝数为2,2株拷贝数为3,拷贝数为5、8和17的分别为1株。初步证明玉米pepc基因已整合到小麦基因组中,且外源基因在转基因植株中既有单拷贝插入,也有多拷贝插入,这为进一步研究该基因在小麦基因组中的功能表达提供了试验材料。

根癌农杆菌介导获得稗草Ecppc转基因小麦的研究

采用携带pUbi-Ecppc质粒的3个根癌农杆菌菌株(LBA4404、EHA105和C58c1),对经过预培养10-12 d的春小麦品种扬麦158、Bobwhite和扬麦12的幼胚愈伤组织进行了遗传转化,对筛选中的抗生素浓度、菌液浓度、共培养温度和时间、受体基因型、菌株-质粒组合等影响转化的重要因素进行了研究。首次将单子叶野生C4植物稗草的磷酸烯醇式丙酮酸羧化酶基因(Ecppc)导入不同基因型小麦受体,并得到具有潮霉素(Hyg)抗性的转化植株。从816块共培养愈伤组织中转化得到34株抗性植株,其中14株PCR检测为阳性。扬麦158的转化效率达3.03%。Southern和RT-PCR分析表明,外源基因已整合到小麦基因组并得到正确的转录。生理学检测显示,转基因小麦植株的光合速率和PEPC活性都有所提高。说明Ubiqintin基因启动子控制的稗草PEPC cDNA基因在小麦中可以正确表达和起到一定的生理作用。这些工作为进一步探讨PEPC对小麦光合作用及其他生理过程的影响奠定了基础。

盐胁迫下野大麦耐盐生理机制初探

以盐生植物野大麦、甜土植物中国春小麦为材料,研究了NaCl胁迫对野大麦、小麦幼苗叶片质膜透性、含水量、地上和根部离子含量、脯氨酸含量、磷酸烯醇式丙酮酸羧化酶(PEPCase)活性的影响。结果表明,随盐胁迫浓度增加,野大麦的细胞膜透性、Na+含量、脯氨酸含量、Na+/K+、PEPCase活性增加,含水量、K+含量下降;但在相同盐胁迫条件下野大麦地上部和根部Na+含量明显低于小麦,而根中K+含量高于小麦,表明野大麦可能具有拒绝吸收Na+和维持高K+含量的能力;野大麦的脯氨酸含量增加幅度小于小麦,表明在盐胁迫下野大麦不是通过脯氨酸的积累来达到体内渗透平衡的;野大麦PEPCase活性增加明显高于小麦,说明提高光合效率可能是野大麦实现盐适应的主要措施之一。

田间条件下转玉米C4型PEPC基因小麦的光合生理特性

为了检验转PEPC基因小麦是否具有C4光合生理特性,以转PEPC基因小麦和对照周麦19为试验材料,分别于抽穗期、开花期、花后第7天和花后第15天测定其单株旗叶的气体交换参数日变化,对净光合速率日变化进行单位日光合总量分析,并且对净光合速率日变化与单株气孔导度、胞间CO2浓度、蒸腾速率日变化的相关性进行了分析;在花后第15天测定其单株叶绿素荧光参数,并在成熟期调查了单株产量性状。与对照相比,转基因株系在4个测定时期的旗叶净光合速率明显提高,尤其在花后第15天,单位日光合总量较对照提高29.1%和23.3%,气孔导度和蒸腾速率均明显增加,胞间CO2浓度降低;花后第15天12:00与8:00相比,转PEPC基因小麦的Fv/Fm、qP、NPQ、ΦPSII的变幅均小于对照;单茎重、千粒重、单穗重和收获指数较对照显著增加。以上结果表明,转PEPC基因小麦材料在田间条件下光合特性明显优于对照,且具有提高小麦产量水平的潜力。