Establishment of homozygous transgenic rice lines after elimination of unlinked albino traits from transgenic events through segregation

In an analysis of 339 independent T 0 transgenic rice lines generated by Agrobacterium -mediated transformation, albino plants appeared in the T 1 generation in two single-copy transgenic lines, O54 and O36 and in one double-copy transgenic line, C18. While the T 0 plants of these three lines were green, albino and green plants emerged in a 1:3 ratio in the T 1 generation. The albino phenotype segregated as a monogenic recessive trait. Southern blot analysis of the green and albino plants in the T 1 generation confirmed that the albino trait and the T-DNA insertion events were unlinked. Segregation of the albino trait from the transgenic trait in the lines O54 and O36 was confirmed in T 2 and T 3 generations, respectively. Homozygous transgenic plants free from the albino trait were also identified. In the double-copy transgenic line C18, we genetically separated the two transgenic loci, out-segregated the albino locus from both transgene loci, and identified homozygous plants for each of the transgenic events by Southern blot analysis in the T 1 generation itself. Thus, we demonstrate that when an albino trait appears in the T 1 generation and is unlinked to a transgene locus, the albino locus can be segregated from the transgene locus and homozygous transgenic lines free from albinos can be established.