Sorry in advance for the somewhat naive question.
Is it overstepping to claim each individual plant isolated from a floral dip
transformation is an independent transgenic line?
According to work by Clough & Bent (among others), via floral dip, "T-DNA
insertion events derived from the same plant are generally independent." I can
find no guidelines for independence, though. Some journals require multiple
independent transgenic lines, but I don't believe they require a Southern blot
or sequencing analysis to actually prove independence. Taken together, that
makes me feel that it is generally accepted that, when doing Arabidopsis floral
dip, each transformant can just be assumed to be independent. Would that be a