3.4　Open reading frames(ORFs)

In total，73 ORFs were identified by MFannot in addition to the conserved genes，which is a little higher than that predicted by Li et al.(2015).The difference in ORF number may be due to different method used.The fungi in Hypocreales exhibited a broad spectrum of predicted ORFs in this study，from the least(n=1)in Metacordyceps chlamydosporia(Lin et al.，2015)to the most(n=73)in O.sinensis(Table 1).The length of the ORFs in O.sinensis ranged from 306bp to 2397bp，with a total length of 59，421bp accounting for 37.72%of the mt genome of O.sineneis.The variation in the number and length of predicted ORFs could partly explain the variation in genome size.(https://www.daowen.com)

Among the 73 ORFs，12 were free-standing，and the rest were located in introns.Among free-standing ORFs，only ORF_71 was predicted to be a DNA-directed RNA polymerase，while the functions of the others were unknown.In addition to the ORFs that exhibited similarities to GIY-YIG/LAGLIDADG endonuclease or RTs in introns，there were some ORFs encoding domains of intron encoded nuclease repeat and nucleaseassociated module，which are possibly involved in DNA-binding.