Inheritance and expression of transgenes in T2 and T3 generations of Lotus corniculatus transformed using Agrobacterium tumefaciens

Abstract

The inheritance and expression of the reporter gene uidA, encoding β-glucuronidase (GUS), was previously analysed in the T1 generation of 25 independent transformed lines of Lotus corniculatus cv. Leo. In the work reported here, GUS activity in various tissues of seven of these lines was tested in the T2 generation. Four representative lines were chosen for more detailed study in the T3 generation. Lines 25 and 38 had multiple, independently segregating transgene inserts; lines 24 and 39 appeared to transmit one segregating transgene insert to their T1 progeny, although transgene expression was low and was detected in fewer seedlings than expected in line 39. The uidA gene was inherited and expressed in seedlings of T1, T2 and T3 generations of all four lines. In all lines, transgene expression varied between tissues, with more embryos than seedlings having detectable GUS activity. Studies in the T2 generation showed that use of transgenic plants as female or male parents altered the frequency of expression of the transgene in progeny. By contrast, in the T3 generation the use of transgenic plants as female or male parents did not effect either frequency of transmission, or expression of the transgene, in any of the four lines. Transgene inheritance was also similar among individual pods within flower heads and between individual flower heads.