Fig. 3

Confirmation of homoplasmy by PCR and spot test. a The original strain of Chlamydomonas reinhardtii TN72 gives a product of 0.88 kb with F1 and R1 primers, while the transformants yield a product of 1.2 kb with some non-specific amplifications. The presence of a 1.2 kb band instead of a 0.88 kb band confirms that all transformants are homoplasmic. b Spot test shows that the original strain of TN72 grows in the presence of spectinomycin (spec) as it consists of spec resistant cassette (upper panel), which is lost after transformation due to which homoplasmic transformants cannot manifest phototrophic growth in the presence of spectinomycin (lower panel). + PSII; the presence of photosystem II, -PSII; absence of photosystem II