Applicability of Cytoplasmic Male Sterility （CMS） as a Reliable Biological Confinement Method for the Cultivation of Genetically Modified Maize in Germany

The cultivation of genetically modified （GM） plants requires the reduction of an unwanted spread of genes （biological confinement）. Cytoplasmic male sterility （CMS） inhibits the development of functional pollen, but nuclear restorer （RJ） genes and environmental impacts can restore the fertility. The aim of this study was to verify whether CMS in maize hybrids is a reliable confinement method for the prospective cultivation of GM maize in Germany. Two-year field experiments in three different environments were conducted with three CMS maize hybrids which vary in the CMS stability, one conventional maize variety （all yellow kernels） and white maize as pollen recipient. Tassel characteristics, pollen vitality and cross-pollination rates were investigated. The CMS stability was dependent on the genotype and the specific weather conditions per year and location. In all maize hybrids CMS was unstable. One CMS maize hybrid showed a high level of CMS stability and very low cross-pollination rates in any case （〈 1%）. The two other CMS maize hybrids developed more fluctuant and fertile tassels with few or many pollen, respectively. Compared with a conventional and fully fertile maize variety, cross-pollination of all CMS maize hybrids was strongly reduced （84%-99%）. In conclusion, the CMS trait can be proposed as a useful biological confinement method to reduce pollen-mediated gene flow from GM maize.

A Real-time Fluorescent Quantitative PCR Method for Detection of Genetically Modified Maize MON88017

In order to improve the standardized technical system of quantitative analyses for genetically modified organisms( GMOs) and protect China's bio-safety and reduce ecological risk,we establish a quantitative detection method for the genetically modified( GM) maize MON88017 using real-time fluorescent quantitative PCR. Meanwhile,the method is evaluated by several methodological indicators such as specificity,sensitivity,accuracy and uncertainty of measurement. The results show that the method has strong specificity in analysis of genetically modified maize MON88017. The mean value(1. 54%) repeatedly measured for 29 times with the relative deviation of 2. 7% was close to the real value(1. 50%) and the variation coefficient of the measured value was 0. 1. The tested recovery rate is 100% and the uncertainty of measurement is 0. 096. 5 copies of the MON88017 molecular fragment can be detected at 97. 5% confidence level. Consequently,the quantitative detection method established in this paper for the GM maize MON88017 has fairly high specificity,accuracy and sensitivity and this technology established in this paper can provide good technical support for the safety supervision of genetically modified organisms in China.

Influence of Soil Moisture and Air Temperature on the Stability of Cytoplasmic Male Sterility (CMS) in Maize (Zea mays L.)

Cytoplasmic male sterility (CMS) is a maternally inherited trait that suppresses the production of viable pollen. CMS is a useful biological tool for confinement strategies to facilitate coexistence of genetically modified (GM) and non-GM crops in case where it is required. The trait is reversible and can be restored to fertility in the presence of nuclear restorer genes (Rf genes) and by environmental impacts. The aim of this study was to investigate the influence of the level of irrigation on the stability of CMS maize hybrids under defined greenhouse conditions. Additionally the combination of irrigation and air temperature was studied. Three CMS maize hybrids were grown with different levels of irrigation and in different temperature regimes. Tassel characteristics, pollen production and fertility were assessed. The CMS stability was high in hot air temperatures and decreased in lower temperatures. The level of irrigation had no major effect on the level of sterility. The extent of these phenomena was depending on the genotype of CMS maize and should be known before using CMS for coexistence purposes.