D NA ▁trans fers ▁into ▁the ▁nucle us . ▁ ▁As ▁shown ▁in ▁figure ▁ 2 b , ▁direct ▁integration ▁of ▁un ed ited ▁m t D NA ▁fragments ▁into ▁the ▁nuclear ▁genom es ▁is ▁the ▁most ▁pla us ible ▁and ▁the ▁evidence ▁both ▁found ▁in ▁plants , ▁Arab id opsis ▁gen ome , ▁and ▁animals ▁with ▁the ▁help ▁of ▁different ▁methods , ▁including ▁B LA ST - based ▁analysis . ▁In ▁this ▁case , ▁m t D NA ▁is ▁transferred ▁into ▁the ▁nucle us ▁where by ▁editing ▁and ▁intr ons ▁arise ▁in ▁the ▁mit och ond r ion ▁later . ▁If ▁a ▁gene , ▁for ▁instance , ▁was ▁transferred ▁to ▁the ▁nucle us ▁in ▁one ▁line age ▁before ▁mit och ond rial ▁editing ▁evol ved , ▁but ▁remained ▁in ▁the ▁organ elle ▁in ▁other ▁line ages ▁where ▁editing ▁arose , ▁the ▁nuclear ▁copy ▁would ▁appear ▁more ▁similar ▁to ▁an ▁edited ▁trans cript ▁than ▁to ▁the ▁remaining ▁mit och ond rial ▁copies ▁at ▁the ▁edited ▁sites . ▁Another ▁represented ▁and ▁less ▁supported ▁model , ▁figure ▁ 2 a , ▁is ▁the ▁c D NA - medi ated ▁model , ▁which ▁intr on - cont ained ▁m t D NA ▁enters ▁the ▁nucle us ▁and ▁by ▁reverse ▁trans cription ▁of ▁sp lic ed ▁and ▁edited ▁mit och ond rial ▁trans cript , ▁it ▁becomes ▁integrated ▁into ▁the ▁n D NA . ▁The ▁third ▁proposed ▁mechanism ▁is ▁the ▁direct ▁transfer ▁and ▁integration ▁of ▁intr on less ▁m t D NA ▁into ▁the ▁nucle us ,