The Segregation Pattern Of Insect Resistance Genes In The Progenies And Crosses Of Transgenic Rojolele Rice

Abstract

Successful application of genetic transformation technique, especially in developing rice variety resistant to brown plant hopper and stem borer. will depend on trans gene being expressed and the gene inherited in a stable and predictable manner. This study aimed to analyse transgene segregation pattern of the progenies and the crosses of transgenic rice cv. Rojolele harboring crylAb and gna genes. The third generation (T1) of five transgenic Rojolele events containing gna andlor cry 1 Ab were evaluated for two generations to identify the homozygous lines and to study their inheritance. The homozygous lines were seleetcd based on the result of peR technique. The segregation patterns of gna and crylAb were studied in eight F2 populations derived from Rojolele x transgenic Rojolele homozygous for crylAb and or gna and their reciprocal crosses. Data resulted from PCR of F 1 population were analysed using a Chi Square test. The study obtained six homozygous lines for gna, namely A22- 1-32, A22-1-37, C72-1-9, FII-I-48, K21-1-39. K21-1-48, and two homozygous lines for cry l Ab, namcly K21-\-39 and K21- 1-48. Both cry 1 Ab and gna transgcnes had been inherited through sclfing and crossing with their wild type as indicated from the FI containing gna and crylAb as many as 48.4% and 47.4%, respectively. In six of the eight crosses, gna was inherited in a 3:1 ratio consistcnt with Mendelian inheritance of a single dominant locus, while in the remaining two crosses, gna was segregated in a I: 1 ratio. The presence of cry I Ab in F2 populations also showed a 3:1 segregation ratio in all crosses. In the Fl popUlation derived from PI plant containing crylAb and gna, both trans genes segregated in a 9:3 :3: I dihybrid segrcgation ratio. This study will add to the diversity of genetic sources for insect resistance and allow further usc of these transgenic lines for pyramiding resistance to brown plant hopper and stem borer or separately in rice breeding programs whenever the efficacy tests and biosafety requirements have been completed.