( Interestingly ( , ( ( their cells ) ( ( contain ( ( not only ) ( ( ( ( 35-kb ( plastid DNA ) ) , ) ( but also ) ) ( ( a modified ) plastid ) ) ) ) . ) ) ) )
(ROOT (S (ADVP (RB Interestingly)) (, ,) (NP (PRP$ their) (NNS cells)) (VP (VBP contain) (NP (CONJP (RB not) (JJ only)) (NP (JJ 35-kb) (JJ plastid) (NN DNA)) (, ,) (CONJP (CC but) (RB also)) (NP (NP (DT a) (NN modified)) (VP (VBN plastid))))) (. .)))
Interestingly, their cells contain not only 35-kb plastid DNA, but also a modified plastid.
(ROOT (S (PP (IN Like) (NP (NN mitochondria))) (, ,) (NP (NNS plastids)) (VP (VBP contain) (NP (PRP$ their) (JJ own) (NN dna))) (. .)))