Morus is an economically significant crop and strong saline-alkali tolerance belonging to the Moraceae family which is native to China and also been planted in various areas for erosion control and windbreaks all over the world (He N, 2013). Great value as a food for healthy M. alba also can be used as a herbal medicine to cure fever, improve eyesight, strengthen joints, and lower blood pressure in China(Chan et al., 2016).
The mitochondrial(mt) genome is power source for energy synthesis and conversion, providing energy protection for various physiological activities of cells(Kozik, Rowan, Lavelle, Berke, & Christensen, 2019) such as cell differentiation, apoptosis,cell growth and cell division(Rehman et al., 2012).In addition,it is also involved the synthesis and degradation of several compounds(Shtolz, Dan, & Evolution, 2019),therefore, mitochondrial play an essential role in plant productivity and development (Yasunari et al., 2005).The mt genome with highly conserved, but the mt genomes has significant differences in length,gene sequence and content(Richardson, Rice, Young, Alverson, & Palmer, 2013).The smallest known terrestrial plant is about 66 Kb,and the largest terrestrial plant mt genome length is 11.3 Mb(Daniel et al., 2012; Skippington, Barkman, Rice, & Palmer, 2015),mostly vary from 200 kb to 3Mb and larger than mt genomes of other eukaryotes(X. & Physiology, 2006).The mt genome structures are shaped by active recombination, gene transfer to the nucleus, and other forces that remain unclear show that by Physical mapping and sequencing of some of the small mt genomes(Woloszynska, 2009).Structural analyses revealed high frequencies of intra- and intermolecular recombination,which generated a structurally dynamic assemblage of genome configurations(Alverson et al., 2010).The mt genome are inherited from the maternal parent(Wolfe, Li, & Sharp, 1988),this provides a powerful model for the study of genome structure and evolution,also a certain advantages in phylogenetic reconstruction.These genomes exhibit an intriguing mixture of conservative (slowest rates of nucleotide substitution)(Drouin, Daoud, Xia, & Evolution, 2008) and dynamic evolutionary patterns.Some previous reported(Tong, Kim, & Park, 2016) also suggested that for evolutionary studies it is not necessary to assemble whole organelle genomes but just exploring the variations.
Currently, With the rapid development of sequencing technology,an increasing number of complete plant mt genomeswere assembled and reported Up to Jan. 2021, 351 complete mt genomes have been deposited in GenBank Organelle Genome Resources(Cheng, He, Priyadarshani, Wang, & Qin, 2021).However,the mt genome of Morus is incomplete and unexplored..In this study, we sequenced and annotated the mt genome of cultivated Morus(M. atropurpurea and M. multicaulis) and compared it with the wild M. notabilis(NC-041177.1) and other eudiot which provides additional information for a better understanding of the genetics of the Morus L.