Analysis of the Genetic Stability of Insect and Herbicide Resistance Genes in Transgenic Rice Lines: A Laboratory and Field Experiment

Abstract

AbstractA lack of stability in the expression of Bacillus thuringiensis genes (CRY) and the dialaninophosphate resistance gene (BAR) in transgenic rice plants can lead to the loss of important characters. The genetic stability of transgenic expression in high-generation lines is thus critically important for ensuring the success of molecular breeding efforts. Here, we studied the genetic stability of resistance to insect pests and herbicides in transgenic rice lines at the molecular and phenotypic levels in a pesticide-free environment. Southern blot analysis, real-time polymerase chain reaction, and enzyme-linked immunosorbent assays revealed high stability in the copy numbers and expression levels of CRY1C, CRY2A, and BAR in transgenic lines across different generations, and gene expression levels were highly correlated with protein expression levels. The insecticide resistance of the transgenic rice lines was high. The larval mortality of Chilo suppressalis was 50.25% to 68.36% higher in transgenic lines than in non-transgenic control lines. Percent dead hearts and percent white spikelets were 16.66% to 22.15% and 27.07% to 33.47% lower in transgenic lines than in non-transgenic control lines, respectively. The herbicide resistance of the transgenic rice lines was also high. The bud length and root length ranged were 2.53 cm to 4.20 cm and 0.28 cm to 0.73 cm higher in transgenic lines than in non-transgenic control lines in the budding stage, respectively. Following application of the herbicide Basta, the chlorophyll content of the transgenic lines began to recover 2 d later in the seedling and tillering stages and 3 d later in the booting and heading stages, by contrast, the chlorophyll content of the non-transgenic lines did not recover and continued to decrease. These findings revealed high genetic stability of the resistance to insect pests and herbicides across several generations of transgenic rice regardless of the genetic background.