There have been several major cases in the international debate on the biosafety of genetically modified (GM) crops, including the following. (i) The case of Pusztai's claim in 1998 that GM potato with inserted gna gene from snowdrop caused adverse effects on rat health. The peer review led by the UK Royal Society concluded that Pusztai's results were incorrect in many aspects and no such adverse effects should be inferred from them. (ii) In 1999, Nature published a paper by a group from Cornell University in which it was reported that the larvae of monarch butterfly were killed by the pollen of Bt corn on milkweeds. Subsequent laboratory and field studies have shown that pollen of Bt corn does not harm the monarch butterfly. The decline in population density of the monarch butterfly is caused mainly by the overuse of pesticides and environmental changes occurring in Mexico. (iii) In 1998, volunteer canola resistant to three herbicides was reported in a canola producer's field in northern Alberta, Canada, which was then called a ‘super weed’ by activists. In fact, ‘super weed’ is not a scientific term and no such case exists in nature: the triple-resistant volunteer canola can be killed by spraying with the herbicide 2,4-dichlorophenoxyacetic acid. (iv) In November 2001, Quist and Chapela published a paper in Nature claiming that DNA sequences similar to the CaMV35S promoter and adh1 gene used in GM corn Bt 11 were found in samples of maize landraces collected from Oaxaca, Mexico. Subsequent scientific analyses demonstrated that the sequence of the 35S promoter detected was an artefact and the sequence of adh1 was adh1-F, a native gene in maize and not the adh1-S transgene used in Bt 11. (v) In June 2002, Greenpeace published a report which stated ‘Bt cotton damaged the environment in China’. The positive benefits of Bt cotton in China were not cited in Greenpeace's report. The fact is that, as a result of commercialization of Bt cotton, the amount of pesticides used for cotton bollworm control has been dramatically reduced by 70–80%. Therefore, the population size of predators and the diversity of arthropods in Bt cotton fields have increased drastically, which resulted in a dramatic reduction of the aphid population by 443- to 1546-fold in Bt cotton fields compared with non-Bt cotton fields. Monitoring bollworm populations nationwide in cotton-growing areas has shown that none of them has developed resistance to the Bt protein or to Bt cotton to date. The migration behaviour of the bollworm, the inheritance of insect resistance to Bt controlled by an incomplete recessive gene, the existence of ‘natural refugia’ in multiple-cropping systems in North China and the use of transgenic cotton with double genes (Bt/CpTI) have all played important roles in delaying the development of resistance to Bt cotton in bollworm populations. In conclusion, international debates on the biosafety of GM crops are not purely a scientific issue, but are related to economic and trade considerations.

AFLP provides an effective, rapid and economical tool for detecting a large number of polymorphic genetic markers that are highly reliable and reproducible, and are able to be genotyped automatically. The AFLP technique has been used extensively to detect genetic polymorphisms, evaluate and characterize breed resources, construct genetic maps and identify genes. In this paper, we describe the optimization of the AFLP technique for porcine genomic DNA fingerprinting, including the enzyme digestion, adapter ligation, preamplification, selective amplification, denatured PAGE, silver staining and multicolour fluorescent detection. Twenty-eight polymorphic markers were detected in the pooled genomic DNA of 44 pig breeds (populations) by E32/T32 primer combinations.

Two pairs of nested primers were derived from the 5′ flanking sequence of the bovine SRY gene to serve as male-specific sexing primers, which were used for PCR-based sex determination of bovine embryos in combination with casein protein gene primers as internal control. At the same time, methods of DNA extraction from bovine embryo cells were established and the sensitivity of nested PCR and normal PCR was studied for developing a technique of sex determination of bovine embryos adapted for practical use. Results showed that the primers used in the study were male-specific and all primers were bovine-specific. Boiling and freeze–thawing were used for DNA extraction from embryo cells. Amplification products were obtained with only 10 cells by nested PCR, so this system was used for the sex determination of bovine embryos. The sex of 10 Holstein cow embryos was identified and the results were confirmed upon birth of the calves.

The effects of insect-resistant transgenic cotton on the diversity of arthropod communities in cotton fields in North China were investigated during 2000–2001. The field experiments were conducted in non-insecticide treated plots of transgenic cotton lines (SGK321, a transgenic cotton variety carrying Cry1A+CpTI genes; GK12, a transgenic cotton variety carrying the Cry1Ac gene) and their conventional parent varieties (Shiyuan 321 and Shimian 3, respectively), and in sprayed plots of the parent varieties where pyrethroid insecticides were used regularly against the cotton bollworm. All the arthropods were sucked up using a portable suction device and identified to species wherever possible. They were later sorted into guilds (pests, natural enemies and neutral arthropods) for diversity analysis using the method of Shannon's index. The diversity of arthropod communities in transgenic cotton plots was similar to that in conventional cotton fields without spraying, but Shannon's index for total arthropod community and the neutral arthropod guild in Bt cotton fields were significantly higher than those in sprayed plots in the mid and late growing stages of cotton. It is concluded that planting of Bt cotton could increase the stability of arthropod communities in cotton ecological systems and benefit the management of insect pests in cotton.

The distribution of genetic diversity between Oryza sativa L. ssp. indica and O. sativa L. ssp. japonica covering different ecological zones in Yunnan was studied, and specific markers of indica/japonica subspecies, paddy/upland rice and different ecological zones were screened, using 36 microsatellite primers and 113 accessions in the Yunnan landrace rice core collection. The genetic diversity of japonica was higher than that of indica, and the ecological zone with the highest and smallest genetic diversity lay in south-east and north-east Yunnan, respectively. This distribution was consistent at morphological and isozyme levels with studies on the entire Yunnan rice resources and core collection. In addition, the results showed that, among 416 markers, there were six indica/japonica-specific markers, 15 specific markers for paddy/upland rice and three specific markers in different ecological zones. The main conclusions are that the landrace rice core collection in Yunnan genetically represents the entire landrace rice resources in Yunnan, the centre of genetic diversity at DNA level lies in south-east Yunnan, and the DNA differentiation between indica and japonica is small. Furthermore, microsatellite markers were useful for studying the genetic diversity, classification and ecotype of germplasm resources and their core collection.

DNA was extracted from kernels of genetically modified (GM) Roundup Ready soybean (Glycine max), made to a series of dilutions, and then used template for amplification by nested PCR and semi-nested PCR. The template comprising a 10−14 g/μl DNA solution could be amplified by both nested and semi-nested PCR. Various soybean foodstuffs and foods from a local supermarket were tested by nested and semi-nested PCR. The soybean housekeeping gene lectin could be amplified from 10 types of food (17 different brands), including soybean oil, sauce, lecithin, tofu, soybean milk and soy milk. The CaMV35S-CPT4 segment was amplified from eight types of food (14 brands), indicating that these foods were manufactured using soybean Roundup Ready ingredients. Therefore, nested and semi-nested PCR could serve as efficient methods in detecting GM soybean in foodstuffs and foods.

The olfactory sensors of insects' antennae, which are directly exposed to the environment, play an important role in identifying volatile hydrophobic molecules in the air. As many odours in the air are cytotoxic xenobiotics, there must be mechanisms in insects' antennae to decompose the molecules and also redundant odorant stimulators. In the present study, differential display PCR was used to isolate three antenna-specific mRNAs from the moth of the cotton bollworm, Helicoverpa armigera. Sequence analysis of the A4-1 clone indicated that it was homologous to the glutathione-S-transferase (GST) protein family. Northern blotting showed that the A4-1 clone was expressed specifically in the antennae of H. armigera and the expressed level was higher in male antennae than in female ones; this is similar to the expression of PBP-Harm gene from cotton bollworm. According to the gene's expression in antennae and the role of GST reported in other insects, the gene is predicted to be responsible for the decomposition of pheromones and harmful xenobiotics in antennae.

Ninety-nine individual plants of a segregating F2 population of a wheat single cross Wen 6×CP90.0.2.4.1 were used in this study to find out whether CP90.0.2.4.1, a derivative of Triticum spelta var. album, carries a novel stripe rust resistance gene other than Yr5. Using molecular marker technology, it was found that only one out of 150 SSR primers could produce amplified polymorphism, and a marker, Xgwm155-147bp, located on chromosome 3A, was found to be linked to the stripe rust resistance gene identified with a genetic distance of 40.5 cM, indicating that the latter was also located on chromosome 3A. Since the only Yr gene previously reported to originate from T. spelta var. album is Yr5, located on 2BL, the only logical inference is that there might be other Yr gene (genes) in T. spelta, and the Yr gene identified in the present study might be a novel one. It was temporarily designated YrSp.

Rice grassy stunt virus (RGSV), a member of the genus Tenuivirus, is composed of a single nucleocapsid protein and six genomic ssRNA segments. Based on the known RNA sequence of the RGSV-IR isolate, primers were designed and cDNA of the NS3 gene was obtained by reverse transcription of the virus sense (v) RNA3 and PCR amplification, with genomic RNAs of RGSV-SX isolate as template. The cDNA was then cloned and sequenced. The NS3 gene comprised 588 nt and the sequence identities were 99.1%, 96.2% at the nucleotide level and 98.4%, 96.4% at the amino acid level, compared with those of RGSV-IR and -SC isolates. The 22.9 kDa NS3 protein encoded by RGSV-SX vRNA3 showed 33.0% identity to the 21.6 kDa protein encoded by vRNA5 of RGSV over a span of 80 amino acids, and no other significant matches were found in the GenBank database. The NS3 gene was cloned in pGEX-2T to generate a prokaryotic expression plasmid pGTNS3, and a fusion protein of GST-NS3 at 49.0 kDa was induced in Escherichia coli. Antiserum prepared to this protein reacted with NS3 encoded by RGSV in Western blots. The protein was detected only in infected rice (Oryza sativa), not in purified virus or viruliferous planthopper vectors. Thus NS3 appears to be a protein encoded abundantly only while the virus infects the rice host plant and may be related to the virus pathogenesis.

The rabbit defensin gene NP-1 was introduced into embryonic callus cultures of three maize (Zea mays L.) hybrid lines by particle bombardment, and transgenic plants were obtained. Genomic PCR and DNA dot blot analyses confirmed that the NP-1 gene was integrated into the genome of the regenerated T0 maize plants. Genomic PCR and Southern blotting results revealed that the NP-1 gene was transmitted stably from the T0 to the T1 generation. RNA dot blot analysis verified the transcription of the NP-1 gene in T1 plants. When challenged with northern corn leaf blight (Helminthosporium turcicum Pass), the T1 plants expressing the NP-1 gene showed greatly improved resistance to the fungal disease compared with the wild-type maize plants.

Ginseng hairy roots were induced from root explants of ginseng by the co-culture of Agrobacterium rhizogenes and ginseng (Panax ginseng C. A. Mey) roots through direct inoculation. The content of ginsenosides in the ginseng hairy roots after 4 weeks of culture reached the same level as in 3-year-old cultivated ginseng roots, and the content of one ginsenoside (Rb1) increased, showing that left transferred DNA (TL-DNA) has a function of influencing the biosynthesis of ginsenosides. Based on analysis of the RiA4TL-DNA sequence, the rolC gene affecting the synthesis of ginsenosides was amplified and cloned from the ginseng hairy roots by PCR. Comparison with a previously published nucleotide sequence showed that the homology was 99.9%.