A High-Quality Assembly Reveals Genomic Characteristics, 1
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A High-Quality Assembly Reveals Genomic Characteristics, 1 Phylogenetic Status and Causal Genes for White Feather of 2 Indian Peafowl shaojuan Liu South China Agricultural University College of Animal Science hao Chen Jiangxi Science and Technology Normal University School of Life Science jing Ouyang Jiangxi Science and Technology Normal University School of Life Science min Huang South China Agricultural University College of Animal Science hui Zhang South China Agricultural University College of Animal Science sumei Zheng South China Agricultural University College of Animal Science suwang Xi Jiangxi Agricultural University College of Animal Science and Technology hongbo Tang Jiangxi Science and Technology Normal University School of Life Science yuren Gao Jiangxi Science and Technology Normal University School of Life Science yanpeng Xiong Jiangxi Science and Technology Normal University School of Life Science di Cheng Jiangxi Agricultural University College of Animal Science and Technology kaifeng Chen Jiangxi Agricultural University College of Animal Science and Technology bingbing Liu South China Agricultural University College of Animal Science wanbo Li Jimei University xueming Yan Jiangxi Science and Technology Normal University School of Life Science huirong Mao ( [email protected] ) Jiangxi Agricultural University https://orcid.org/0000-0003-2588-1521 jun Ren South China Agricultural University College of Animal Science Research Keywords: Indian peafowl, Genome assembly, Phylogeny, PMEL, White feather Posted Date: July 1st, 2021 DOI: https://doi.org/10.21203/rs.3.rs-650113/v1 License: This work is licensed under a Creative Commons Attribution 4.0 International License. Read Full License 1 A high-quality assembly reveals genomic characteristics, 2 phylogenetic status and causal genes for white feather of 3 Indian peafowl 4 Shaojuan Liu1#, Hao Chen3#, Jing Ouyang3, Min Huang1, Hui Zhang1, Sumei Zheng1, 5 Suwang Xi2, Hongbo Tang3, Yuren Gao3, Yanpeng Xiong3, Di Cheng2, Kaifeng Chen2, 6 Bingbing Liu1,Wanbo Li4, Xueming Yan3*, Huirong Mao2*, Jun Ren 1* 7 1 College of Animal Science, South China Agricultural University, Guangzhou 510642, 8 China 9 2 School of Animal Science and Technology, Jiangxi Agricultural University, 10 Nanchang 330045, China 11 3 College of Life Science, Jiangxi Science & Technology Normal University, Nanchang 12 330013, China 13 4 Key Laboratory of Healthy Mariculture for the East China Sea, Ministry of 14 Agriculture and Rural Affairs, Jimei University, Xiamen 361021, China 15 # Both authors contribute equally to this paper. 16 * Corresponding author. 17 E-mail address: [email protected] (H. M); [email protected] (X. 18 Y) 19 20 21 22 23 24 25 26 27 28 1 29 Abstract 30 Background: Indian peafowl (Pavo cristatus) attracts people's attention because of the 31 exclusively dazzling phenotypic characteristics. However, little is known about the 32 phenotypic evolution and phylogeny of Indian peafowl at the whole-genome level. So 33 far, there has been no report on the genetic mechanism of the formation of white feather 34 in white feather peafowl. 35 Results: This study assembled a draft genome of Indian peafowl with a genome size of 36 1.05 Gb (the sequencing depth is 362×), and N50 of the contig and scaffold was up to 37 6.2 Mb and 11.4 Mb, respectively. Compared with other birds, Indian peafowl changed 38 in terms of metabolism, immunity, skeletal development and feather development, 39 which provided a novel insight into the phenotypic evolution of peafowl, such as the 40 large body size and feather morphologies. It was confirmed that the phylogeny of Indian 41 peafowl was closer to that of turkey than that of chicken. Specially, it was identified 42 that PMEL was a causal gene leading to the formation of white plumage in blue and 43 white feather peafowl. 44 Conclusions: This study provides a peafowl genome with high-quality as well as a 45 novel understanding in the phenotypic evolution and phylogeny of peafowl among 46 other birds. The results contribute a valuable reference genome to the study of the avian 47 genome evolution. In addition, the discovery of the genetic mechanism of white 48 plumage not only is a breakthrough in the exploration of peafowl plumage, but also 49 provides clues and new ideas for further investigations of the avian plumage coloration 50 and artificial breeding in peafowl. 51 Keywords: Indian peafowl; Genome assembly; Phylogeny; PMEL; White feather 52 53 54 55 56 57 58 59 2 60 Introduction 61 Pavo cristatus, commonly called Indian peafowl or blue peafowl, is the king of birds, 62 representing elegance, honour, beauty, luck, and romance in many Asian cultures 63 (Figure 1a) (Gadagkar, 2003; Kushwaha & Kumar, 2016). Peafowl, belonging to the 64 Aves, Galliformes, Phasianidae, and Pavo, has two species: green peafowl and blue 65 peafowl. Indian peafowl, as the national bird of India, has been widely distributed in 66 Bangladesh, Bhutan, India, Nepal, Pakistan, and Sri Lankan (Kushwaha & Kumar, 67 2016; Ramesh & McGowan, 2009). Commonly, the male Indian peafowl is more 68 attractive than female because of its larger body size and more glittering plumage. 69 Indian peafowl is one of the largest and most beautiful birds in pheasant as a valuable 70 ornamental display with their fan-shaped crests, brightly blue plumage, and glaring tails. 71 Moreover, Indian peafowl is well known as a protein resource, because their meat, 72 internal organs, and bones have high nutritional values, even with medicinal values 73 (Mushtaq-ul-Hassan, Ali, Arshad, Mahmood, & Research, 2012; Paranjpe & Dange, 74 2019; Talha, Mia, & Momu, 2018). 75 With the improvement of whole genome sequencing technology, more and more 76 avian genomes were assembled, such as chicken (Gallus gallus) ("Sequence and 77 comparative analysis of the chicken genome provide unique perspectives on vertebrate 78 evolution," 2004), turkey (Meleagris gallopavo) (Dalloul et al., 2010), duck (Anas 79 platyrhynchos) (Z. Zhang et al., 2018), and other birds (Jarvis et al., 2014), which 80 provided basic references for the study of phenotypic characteristics, evolution, 81 economic traits, and environmental adaptation of birds. As for peafowl, the first draft 82 genome of peafowl was released in 2018. However, the length of scaffold and contig 83 N50 of the assembling were only 25.6 kb and 19.3 kb, respectively (Shubham K. 84 Jaiswal et al., 2018). Subsequently, Dhar, et al. improved peafowl genome by using 85 Illumina and Oxford Nanopore technology (ONT), and the length of scaffold N50 was 86 up to 0.23 Mb (Dhar et al., 2019). The previous studies of peafowl focused on courtship 87 behaviour (Dakin, McCrossan, Hare, Montgomerie, & Amador Kane, 2016), immunity 88 (Wang, Zhao, Liu, Shao, & Xing, 2019), and productivity (Samour, Naldo, Rahman, & 89 Sakkir, 2010). Additionally, most researches on the phylogenetic relationship of 90 peafowl and the Phasianidae were based on the mitochondrial genomes, DNA 91 transposable factors, and partial DNA nucleotide sequences, and the conclusions of 3 92 these researches are still controversial (J. Naseer et al., 2018; Shen et al., 2014; Zhou, 93 Sha, Irwin, & Zhang, 2015). Therefore, a better quality assembly of peafowl genome is 94 needed to provide baseline data for further studies on peafowl. It has been suggested 95 that the grey peafowl pheasant (Polyplectron bicalcaratum) could be the ancestor of 96 peafowl (Bush & Strobeck, 2003). However, the phylogenetic relationships of peafowl 97 with other pheasants are still unclear, though there have been several recent attempts to 98 investigate it. Study on Hainan peafowl pheasant provided evidences to argue whether 99 it is a subspecies of the grey peafowl pheasant (Chang et al., 2008). Zhou et al. (2015) 100 analysed the phylogenetic status of Indian peafowl in Phasianidae by using a complete 101 mitochondrial genome, and found out its closest genetic affinity with green peafowl 102 (Zhou et al., 2015). Sun et al. (2014) revealed the close relationships among Pavo, 103 Polyplectron and Argusianus within the Phasianidae (Sun et al., 2014). It is expected 104 that a more clarified taxonomic status of the peafowl in Phasianidae can be investigated 105 via the high-throughput sequencing technology. 106 Previous studies reported that there were many plumage colour mutants, including 107 white, black, variegated, cameo, and oaten (Ouyang et al., 2009; R. G Somes & Burger, 108 1993; R. G. Somes & Burger, 1991), among which, the most ornamental colour was 109 the white plumage, belonging to leucism rather than albinism since the feather was 110 white but the eyes had melanin pigmentation (Figure 1b). The inherited basis of 111 plumage colour has attracted researchers for a long time. The first report on it suggested 112 that the plumage phenotype of peafowl was determined by autosomal genes in a 113 recessive model (R. G. Somes & Burger, 1991). Another study verified that a single 114 autosomal locus was in control of all plumage phenotypes in peacock, where the pied 115 colour appeared in two heterozygous mutant alleles, with the black on recessive mutant 116 allele, and the all-white plumage in homozygous mutant allele as the most dominant (R. 117 G Somes & Burger, 1993). Nevertheless, further studies on the genetic mechanism of 118 the white plumage in peafowl are needed, i.e., to clarify the causative mutations of this 119 phenotype. 120 Therefore, a high-quality (near-chromosomal) reference genome of Indian peafowl 121 was constructed by using the third-generation de novo assembly technology. Based on 122 the assembly, it was devoted to investigate the molecular evolution and phylogenetic 123 classification of peafowl in the Phasianidae at the genome-wide level. Subsequently, 4 124 comparative genomics analysis was performed to investigate the biological 125 characteristics of evolution through comparing the genome of Indian peafowl with the 126 high-quality genomes of other birds, human and mouse. Furthermore, the 127 transcriptomic and pooled resequencing data were analysed to identify the genetic 128 mechanism of the white plumage in Indian peafowl.