摘要
T-DNA insertion mutants have been widely used to define gene functions in Arabidopsis and in other plants. Here, we report an unexpected phenomenon of epigenetic suppression of T-DNA insertion mutants in Arabidopsis. When the two T-DNA insertion mutants, yucl-1 and ag-TD, were crossed together, the defects in all of the ag-TD plants in the F2 popumation were partially suppressed regardless of the presence of yucl-1. Conversion of ag-TD to the suppressed ag- TD （named as ag-TD＊） did not follow the laws of Mendelian genetics. The ag-TD＊ could be stably transmitted for many generations without reverting to ag-TD, and ag-TD^＊ had the capacity to convert ag-TD to ag-TD^＊. We show that epige-netic suppression of T-DNA mutants is not a rare event, but certain structural features in the T-DNA mutants are needed in order for the suppression to take place. The suppressed T-DNA mutants we observed were all intronic T-DNA mutants and the T-DNA fragments in both the trigger T-DNA as well as in the suppressed T-DNA shared stretches of identical sequences. We demonstrate that the suppression of intronic T-DNA mutants is mediated by trans-interactions between two T-DNA insertions. This work shows that caution is needed when intronic T-DNA mutants are used.
T-DNA insertion mutants have been widely used to define gene functions in Arabidopsis and in other plants. Here, we report an unexpected phenomenon of epigenetic suppression of T-DNA insertion mutants in Arabidopsis. When the two T-DNA insertion mutants, yucl-1 and ag-TD, were crossed together, the defects in all of the ag-TD plants in the F2 popumation were partially suppressed regardless of the presence of yucl-1. Conversion of ag-TD to the suppressed ag- TD （named as ag-TD＊） did not follow the laws of Mendelian genetics. The ag-TD＊ could be stably transmitted for many generations without reverting to ag-TD, and ag-TD^＊ had the capacity to convert ag-TD to ag-TD^＊. We show that epige-netic suppression of T-DNA mutants is not a rare event, but certain structural features in the T-DNA mutants are needed in order for the suppression to take place. The suppressed T-DNA mutants we observed were all intronic T-DNA mutants and the T-DNA fragments in both the trigger T-DNA as well as in the suppressed T-DNA shared stretches of identical sequences. We demonstrate that the suppression of intronic T-DNA mutants is mediated by trans-interactions between two T-DNA insertions. This work shows that caution is needed when intronic T-DNA mutants are used.
