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

Abstract

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, outsegregated 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.