农杆菌Ri诱导丹参毛状根培养体系的优化

采用发根农杆菌R1601菌株浸染丹参叶片、茎段、叶柄、带节茎段等外植体.结果表明,相比茎和叶柄,丹参叶片更适宜诱导毛状根;带节茎段经发根农杆菌R1601侵染后,幼苗根系较为发达,粗壮.而由其他3种丹参外植体诱导产生的毛状根生长相对较慢,形成的根较细而弱.     

转基因杨树中农杆菌残存状况分析

以转发根农杆菌741杨为材料,在继代和移栽过程中对其残存农杆菌进行追踪检测。结果表明:培养基中附加头孢噻钨纳300 mg/L可将农杆菌基本抑制;随着转化植株在含抗生素培养基中继代时间的延长,残存农杆菌的数量和活性逐步下降,在继代18个月后,无法培养出目的菌落,但转化植株一旦脱离抗生素环境,农杆菌数量和活性又将得到恢复;残存农杆菌主要分布于植株体表和茎中,且影响组培苗PCR检测结果;将转化株系组培苗移栽到花盆半月和田间6个月后,植株体表、体内均未检测到目的农杆菌,但在室内培养半个月后2个株系根际土壤中检测到目的菌落。     

地被菊雨花勋章再生和遗传转化体系的建立

以匍匐型地被菊雨花勋章叶片为外植体,建立了其高频再生体系及根癌农杆菌介导的稳定遗传转化体系.结果表明,不同激素配比对叶片离体再生影响很大,以MS+1.0 mg·L-1 6-BA+1.0 mg·L-1 NAA的诱导率最高,达91.1%;分化前期一定时间的暗培养可防止愈伤组织褐变,提高再生率.预培养3 d,侵染10 min,共培养3 d,延迟培养3 d为最优转化体系;乙酰丁香酮导致外植体褐化加速,不利于转化.叶片对潮霉素十分敏感,叶盘再生筛选以6～8 mg·L-1为宜,生根筛选以7 mg·L-1为宜.羧苄青霉素抑菌质量浓度以250～350 mg·L-1为宜.获得的抗性芽部分株系经PCR检测初步证实外源基因已转入植物基因组DNA中.     

盆栽小菊高效遗传转化体系的建立

采用根癌农杆菌介导的叶圆片遗传转化方法,建立了盆栽小菊稳定而高效的遗传转化体系.试验结果表明:黑暗条件下预培养2d,根癌农杆菌A600约0.5、侵染10 min,共培养3 d,延迟培养5 d能获得较高的转化率;10～15 mg/L的潮霉素具有很好的筛选效果.获得的抗性芽再生植株经PCR检测,初步证实外源基因已转入受体植物的部分株系中.     

农杆菌介导粳稻高效转化体系的研究

以5个粳稻品种为材料,研究农杆菌介导转化中影响粳稻转化的几个重要因素。通过研究发现,根癌农杆菌菌株EHA105的转化率明显高于LBA4404,根癌农杆菌菌株EHA105介导的水稻转化率为25．3％,而LBA4404为7．6％;不同外植体的诱导率、转化率和分化率存在明显差异,以幼胚为外植体材料,它的出愈率和转化率明显比成熟胚高,而分化率则明显低于成熟胚;不同水稻品种在转化率与分化率上差异也很明显,反映了不同基因型水稻品种的差异,同时研究发现同一品种不同批次在转化率和再生频率上差异比较显著,反映了在水稻转化过程中还存在一些未知条件对于转化的影响;通过对抗性愈伤和转化植株的叶片、根的GUS染色,证明GUS基因在不同组织中表达;并且通过PCR和Southern杂交分子分析,发现所检测的植株均为转基因植株,足以证明这个高效转化体系的可靠性。     

根癌农杆菌介导的西瓜遗传转化研究

利用带有内含子的GUS基因的瞬时表达,研究影响根癌农杆菌介导的西瓜遗传转化的若干因素。结果表 明:西瓜子叶块外植体对潮霉素较为敏感,15 mg/L是适宜的筛选浓度,可明显抑制非转化组织的生长;脱菌过程中 采用500 mg/L的头孢霉素,对外植体生长影响较小;农杆菌菌株EHA105对西瓜子叶块的侵染能力较强;预培养有 利于转化;共培养3-4 d有利于提高转化频率并避免了农杆菌的过度生长;OD600值为0.3的菌液侵染10min效果最 佳;共培养培养基中添加乙酰丁香酮可提高转化频率。     

Biotransformation of atrazine in transgenic tobacco cell culture expressing human P450

Plant cell cultures in which the appropriate P450 cDNA is introduced are expected to metabolise certain pesticides in large quantities. Two species of human P450 (CYP1A1 and CYP1A2) were introduced into tobacco cells (Nicotiana tabacum L) by Agrobacterium-mediated transformation. The transgenic plant cell cultures were selected by combination of kanamycin-resistance, 7-ethoxycoumarin O-de-ethylase activity, PCR and Western blot analysis. For metabolism studies, 14C-labelled atrazine was used as a model substance. The metabolites de-ethylatrazine and de-isopropylatrazine were found in the control culture as well as in the transgenic culture, whereas the non-phytotoxic metabolite de-ethyl-de-isopropylatrazine was found only in the transgenic cell cultures. The results showed that both foreign enzymes CYP1A1 and CYP1A2 catalyse N-dealkylation of atrazine. However, CYP1A2 exhibited a higher conversion rate than CYP1A1. In a time-course study the enzyme CYP1A2 catalysed predominantly N-de-ethylation followed by de-isopropylation. The extent of metabolism was considerably higher than in non-transformed cell cultures. The transgenic cell cultures can therefore be suitable tools for the production of large quantities of primary oxidised pesticide metabolites.     

FMDV结构基因P1的克隆与植物双元表达载体的构建

通过RT-PCR法获得阿克苏(Akesu/O/58)FMDV结构基因P1,将该基因克隆到pGEM-T Easy载体进行核苷酸序列测定。将P1基因、Kozak序列等插入中间表达质粒pB in438,构建重组中间表达载体pB inP1。采用三亲融合法构建植物双元表达载体pB inFMDV-P1。结果表明:P1基因为2 208 bp。重组中间表达载体pB inP1经BamHⅠ/SalⅠ双酶切、PCR扩增和序列测定,表明P1基因、Kozak序列等已插入pB inP1。在含50mg/L卡那霉素、25 mg/L链霉素和50 mg/L利福平的YEB培养基上筛选及对融合农杆菌质粒进行P1基因的PCR检测,证明植物双元表达载体pB inFMDV-P1构建正确。     

Interaction of Root-knot Nematodes (RKN) and the Bacterium Agrobacterium Tumefaciens in Roots of Prunus Cerasifera: Evidence of the Protective Effect of the Ma RKN Resistance Genes Against Expression of Crown Gall Symptoms

Agrobacterium tumefaciens (AT) is the causal agent of crown gall, a major problem in the family Rosaceae and particularly for Prunus spp. Crown gall symptoms result from the bacterial infection of the cells damaged mechanically at the collar or by root parasitic nematodes. Myrobalan plum (P. cerasifera) is susceptible to AT and is not a host for the root-knot nematode (RKN), M. hapla. Some clones of this plum carry single Ma resistance genes that control M. arenaria, M. incognita and M. javanica. The four above mentioned RKN and Myrobalan progenies segregating for Ma were used in experiments aimed at obtaining a better knowledge of the interaction between AT and RKN in relation to the RKN resistance genes. Prunus rooted cuttings, naturally infected with the bacterium were repotted, grown and inoculated individually with RKN. In a first experiment, Prunus plants were (i) either inoculated with 10,000 juveniles (J2s) of M. arenaria to provide a short inoculum pressure (SIP) or (ii) inoculated by association with one M. arenaria-galled tomato root system that produced a high and durable inoculum pressure of the same nematode species. Four months after RKN inoculation, plants were rated for nematode and bacterial root galling symptoms. RKN and AT galls were more numerous and more homogenous under DIP than under SIP. Nevertheless, for both inoculum regimes, AT galls were present in the RKN-susceptible clones (= carrying none of the Ma genes) and absent in the RKN-resistant clones. Subsequent experiments, conducted under DIP with M. arenaria, M. incognita, M. javanica and M. hapla, also showed, for the three first species, the presence of AT galls only in RKN-susceptible clones whereas Prunus plants inoculated with M. hapla and nematode-free controls were free of AT galls. Consequently RKN act as a wound agent in the AT infection process of Myrobalan plum only when the plant develops a compatible reaction (i.e. when it lacks the Ma resistance genes). Considering that J2s do penetrate the roots of resistant plants, the absence of crown gall symptoms on this material even under durable inoculum pressure strengthens the hypothesis that this nematode stage has a very weak effect on plant cells during the infection process. This is the first evidence of the protective effect of a RKN resistance gene against the expression of root crown gall consecutive to RKN infection. The protective effect of Ma and presumably of other RKN resistance genes against AT is a strong argument for their introgression into Prunus and other Rosaceae or bacterium-susceptible crops.