Quality Changes Of Bt Transgenic Rice During Hot And Humid Storage

In recent years, with the develepment of the transgenic technology, especically, two transgenic rice "Hua Hui1" and " Bt Shanyou63" have received security certificate. Study on quality changes of genetically modified rice during storage can support for transgenic rice safety evaluation. In this paper, the quality and microorganism diversity change of Bt (Cry1Ac/CrylAb) transgenic rice and non-transgenic parents (as negative controls) in hot and humid storage were studied. The main results are as following:1.The moisture content, lipoxygenase, conductivity, fatty acid value and malondialdehyde content of rice was significantly higher than brown rice during storage. The moisture content increasing rate of transgenic rice was higher than non-transgenic rice, and moisture content of transgenic brown rice increasing rate was lower than non-transgenic brown rice. After storage, the enzymes activity of lipoxygenase from transgenic brown rice was higher than non-transgenic brown rice. No significant difference (P>0.05)existed among conductivity, fatty acid value and malondialdehyde content compared genetically modified rice with non-transgenic rice. Difference of anti-storability in this study between transgenic rice and its negative controls was not obvious, however, brown rice was more resistant than rice during storage. Correlation analysis showed that days of storage, water content, electrical conductivity, fatty acid value and lipoxygenase presented a significant positive correlation, and storage days was correlated to malondialdehyde.2. The microbial diversity of different samples was analysed by using molecular biology technique of denaturing gradien gel electrophoresis during storage. The18S rDNA DGGE profile bands of fungal presented a gradually increasing trend, DGGE profile of16S rDNA lane in the number of bands had no obvious change with time prolonged. In brown rice samples, the number of bands separated from fungus fingerprint were less than that of rice samples. Among which, the similarity of fungus from high maturity transgenic rice and low maturity transgenic rice ranged from25.0%to59.9%. The similarity of fungus was from9.8%to67.8%for transgenic rice and non-transgenic rice. The similarity of fungus varied from54.4%to75.7%for transgenic samples and negative controlled group during storage. The profile results revealed that it had significant difference in fungal diversity between genetically modified samples and its negative controls. Similarity of bacteria from high maturity transgenic rice and low maturity transgenic rice ranged from70.6%to93.0%. The similarity of bacteria transgenic rice and non-transgenic rice varied from81.7%to92.8%. The similarity of bacteria was from71.3%to91.8%for transgenic samples and negative controlled group during storage. The result showed that there was certain difference on microorganism diversity between transgenic samples and negative controls, however, the reason of diversity needs further study.