Establishment of a Construct-specific Real-time PCR Method for Quantitative Detection of Genetically Modified Maize Line MIR604

In this study, a construct-specific real-time PCR method for quantitative detection of genetically modified maize line MIR604 was established with prim- ers and probes designed based on vector sequence of MIR604 under optimized reaction system and thermal cycling condition. By using the established method, six non-genetically modified crops, genetically modified maize line MIR604 and other non-target genetically modified crops were detected. According to the results, flu- orescence signal could be detected in genomie DNA of MIR604, but other non-genetically modified crops and non-target genetically modified crops exhibited no fluo- rescence signal of MIR604 molecular fragment. Certified reference materials containing 1% MIR604 were detected with the established method and the results indi- cated that the average relative content in the test samples was 1.05%. The sensitivity analysis results indicated that MIR604 nucleic acid fragment with at least five copies could be detected with the established method. In conclusion, the construct-specific real-time PCR method for quantitative detection of genetically modified maize line MIR604 is of high specificity, accuracy and sensitivity, which provides technical support for safety supervision of genetically modified organisms in China.

Evaluation of Uncertainty in Measuring the Content of CaM V35S Promoter in Genetically Modified Soybean,GTS40-3-2,by Real-time Quantitative PCR

[ Objective ] This study aimed to investigate the major contributors to the measurement uncertainty in quantitative analysis of genetically modified ingreclients and improve the quality of quantitative detection of genetically modified components. [ Method] The content of CaMV35S promoter （parameter） in GTS40- 3-2 soybean powder samples was measured to estimate the measurement uncertainty preliminarily. [ Result] Type A uncertainty （uA） ＇ type B uncertainty （uB） and combined standard uncertainty （Uc） were 0.0 004, 0.002 and 0.002, respectively. At a confidence level ofp = 95% and freedom degree of Voff = 3 251, coverage factor k = 1.96, expanded uncertainty U = 0.004. The final measurement result was C = 0.028 ± 0. 004, which was dose to the conventional true value （0.03）. Thus, the measurement uncertainty was relatively small, indicating a high quality of measurement. In this study, uncertainty evaluation indicated that the deviation of micro liquid transfer made the greatest contribution to the measurement uncertainty. [ Cludusion ] The deviation of micro liquid transfer should be reduced to im- prove the quality of measurement.

Uncertainty in Detecting Specific Fragment of Genetically Modified Maize Event NK603 by Real-time Fluorescence Quantitative PCR

In this study, the event-specific real-time fluorescence quantitative PCR method established by Siehuan Academy of Agricultural Sciences was employed to detect the content of flanking fragment （specific fragment） in samples containing 2% genetically modified maize event NK603. The uncertainty of detection results was evaluated based on various uncertainty sources, such as PCR amplification system, data analysis and micropipette. The results showed that A-type uncertainty （ uA ）, B-type uncertainty （ uB ）, combined standard uncertainty （ uC ） and expanded uncertainty （ U95 ） were 0. 000 8,0.1301,0. 001 and 0. 002, respectively; the final detection result was 1.9% ±0.002. Thus, the main uncertainty in detecting flanking fragment of genetically modified maize event NK603 with realtime fluorescence quantitative PCR method was derived from the random effect in the experimental process.

Development of an Event-specific Quantitative PCR for Genetically Modified Maize (Zea mays) Event NK603

[ Objective ] The aim of this study was to develop a quantitative PCR detection method for genetically modified maize event NK603, so as to provide ba- sis for quantitative analysis of event NK603. [ Methods ] A quantitative PCR detection method for genetically modified maize event NK603 was developed using primers and Taqman probe designed according to the flanking sequence of event NK603, which was then adopted to detect the samples containing 2% NK603 stand- ard （with uncertain quantity of 10% ）. [ Results ] The slope of standard curve ranged between -3.6 and -3.1, and the correlation coefficient was higher than 0. 99. The amplification efficiency of this method reached 100.2%, fallen between 90% and 110%. The detected quantity of the experimental sample was 1.9%, closer to the true quantity （2%）. [ Conclusion] This quantitative PCR detection method for genetically modified maize event NK603 is very precise and can be a- dopted in routine testing analysis.

A conserved unusual posttranscriptional processing mediated by short,direct repeated (SDR) sequences in plants

In several stress responsive gene loci of monocot cereal crops,we have previously identified an unusual posttranscriptional processing mediated by paired presence of short direct repeated （SDR） sequences at 5＇ and 3＇ splicing junctions that are distinct from conventional （U2/U12-type） splicing boundaries.By using the known SDR-containing sequences as probes,24 plant candidate genes involved in diverse functional pathways from both monocots and dicots that potentially possess SDR-mediated posttranscriptional processing were predicted in the GenBank database.The SDRs-mediated posttranscriptional processing events including cis-and trans-actions were experimentally detected in majority of the predicted candidates.Extensive sequence analysis demonstrates several types of SDR-associated splicing peculiarities including partial exon deletion,exon fragment repetition,exon fragment scrambling and trans-splicing that result in either loss of partial exon or unusual exonic sequence rearrangements within or between RNA molecules.In addition,we show that the paired presence of SDR is necessary but not sufficient in SDR-mediated splicing in transient expression and stable transformation systems.We also show prokaryote is incapable of SDR-mediated premRNA splicing.