Deletions within intronic T‐DNA lead to reversion of T‐DNA mutant phenotypes.

SUMMARY: Agrobacterium‐mediated transformation enables random transfer‐DNA (T‐DNA) insertion into plant genomes. T‐DNA insertion into a gene's exons, introns or untranscribed regions close to the start or stop codon can disrupt gene function. Such T‐DNA mutants have been useful for reverse genetics analysis, especially in Arabidopsis thaliana. As T‐DNAs are inserted into genomic DNA, they are generally believed to be stably inherited. Here, we report a phenomenon of reversion of intronic T‐DNA mutant phenotypes. From a suppressor screen using intronic T‐DNA pi4kβ1,2 double mutant, we recovered intragenic mutants of pi4kβ1, which suppressed the autoimmunity of the double mutant. These mutants carried deletions in the intronic T‐DNAs, resulting in elevated transcription of normal PI4Kβ1. Such reversion of T‐DNA insertional mutant phenotype stresses the need for caution when using intronic T‐DNA mutants and reiterates the importance of using irreversible null mutant alleles in genetic analyses. Significance Statement: Here, we report the phenomenon of reversion of intronic T‐DNA mutant phenotypes by intra‐T‐DNA deletions. Future caution should be taken when using such intronic T‐DNA mutant alleles. [ABSTRACT FROM AUTHOR]