Detection Of Bt Protein Content And Evaluation Of Insect-Resistance And Agronomic Traits Of Transgenic Rice

Lepidopteran insect is one of the major insect pests of rice. It causes severe yield loss. In order to control leaffolders and lepidopteran stemborers, Bt genes have been introduced into rice, and many transgenic rice lines with insect-resistance were obtained. It is necessary to research the characteristics of the transgenic rice, including the expression of Bt genes in rice, insect-resistance, agronomic traits and rice quality.In this study, the transgenic plants harbouring crylAb/Ac, cry1C*genes, respectively, were used as materials. We detected the Bt protein content quantitatively in rice leaves and stems at tillering stage and heading stages, respectively. Under natural condition of the field, we evaluated their insect-resistance, main agronomic traits and rice quality. The main results in this study are as follows:1. We detected CrylAb/Ac protein content of rice varieties TT51, two derived lines Huakanghui317and Huakanghui307, two hybrid combinations Huaxiangyou317(Chuanxiang29A/Huakanghui317) and Jinyou307(Jin23A/Huakanghui307). The results showed, in tillering stage leaves, protein content of TT51, Huakanghui317, Huakanghui307were14.29μg/g FW,12.78μg/g FW and12.42μg/g FW, respectively. In heading stage leaves, protein content of TT51, Huakanghui317, Huakanghui307were14.61μg/g FW,13.56μg/g FW,11.40μg/g FW, respectively. In heading stage stems, protein content of TT51, Huakanghui317, Huakanghui307were18.02μg/g FW,16.25μg/g FW,12.48μg/g FW, respectively. Protein content in tillering stage leaves, heading stage leaves, heading stage stems of Huaxiangyou317were8.48μg/g FW,8.49μg/g FW,9.57μg/g FW, respectively, that of Jinyou307were7.91μg/g FW,7.66μg/g FW,8.09μg/g FW, respectively. Protein content of hybrids were30%lower than that of their male parents. It indicated expression of crylAb/Ac gene had the feature of gene dosage effect.2. Cry1C*protein content detection results showed, in tillering stage leaves, protein content of Tic-19with cry1C*gene was0.65μg/g FW, that of derived line Huakang8530was0.49μg/g FW. In heading stage leaves, protein content of Tic-19and Huakang8530were1.06μg/g FW,0.90μg/g FW, respectively. In heading stage stems, protein content of T1C-19and Huakang8530were0.07μg/g FW,0.05μg/g FW, respectively. Cry1C*protein content of derived line was20%lower than that of its donor parent, this suggested there was difference in expression level of cry1C*gene in rice lines under different genetic background. Protein content in tillering stage leaves, heading stage leaves, heading stage stems of Hualiangyou630(Tianyuan6S/Huakang8530) were0.29μg/g FW,0.40μg/g FW,0.03μg/g FW. Protein content of hybrid was40%lower than that of its male parent, this indicated the expression of cry1C*gene also had the character of gene dosage effect.3. Comparison results of Bt protein content in different sowing dates revealed that Bt protein content in leaves of transgenic lines sowed before April23and sowed after June13were higher than that of transgenic lines sowed on May11and May27. It suggested that expression level of Bt genes decreased under high temperature condition.4. Comparing expressing protein content of two Bt genes, we found that expressing protein content of crylAb/Ac gene were12to22times higher than that of cry1C*gene in leaves, while in the stems, expressing protein content of crylAb/Ac gene were257times higher than that of cry1C gene.5. The CrylAb/Ac protein content in stems at heading stage was higher than that in leaves. The expressing protein content of cry1C gene in different tissues at different growth periods in decreasing order was: leaves at heading stage> leaves at tillering stage> stems at heading stage.6. According to the field insect-resistance evaluation results, all Bt rice lines were not damaged by leaffolders and stemborers. The percentage of damaged leaves by leaffolders of non-Bt rice variety9311was7.4%to10.4%, that of non-Bt rice variety Minghui63was4.9%.7. Huakang8530and Hualiangyou630performed well in main agronomic traits and rice quality, so the two varieties had production value.8. There were eight cry1C*transgenic lines under the genetic background of variety9311. The results of main agronomic traits investigation and rice quality showed that Huakang8526、Huakang8527、Huakang8529、Huakang8530were similar as9311. Chip analysis results indicated that, their genetic background recovery rates were95.65%,96.39%,84.84%,85.90%, respectively.