Detection of Genomic Variation and Tepal Shape Related Genes Between Broad and Narrow Tepal Lotus (Nelumbo Adans.) by whole Genome Resequencing

Background: The shape, color, and size of petals or tepals are vital attributes of flowering plants, as they affect the pollinator attraction ability, environmental stress adaptation, and ornamental value of plants. Compared with rose, chrysanthemum, and water lily, the tepal shapes of lotus (Nelumbo Adans.) exhibit low variation, and the absence of short-broad and long-narrow tepals limits the commercial value of lotus flowers. Therefore, this study aimed to uncover the genomic variation underlying the broad and narrow tepal phenotypes of lotus flowers, and to screen candidate genes associated with different tepal shapes.Results: Whole genome resequencing of two groups of lotus, NL (comprising three American lotus genotypes: broad tepal mutant, narrow tepal mutant, and wild type) and WSH (comprising two Asian lotus genotypes: narrow tepal mutant and wild type), generated 9.23–12.85 Gb clean data. A total of 716,656 single nucleotide polymorphisms (SNPs) and 221,688 insertion-deletion mutations (Indels) were obtained in the NL group, while 639,953 SNPs and 134,6118 Indels were obtained in the WSH group. Only a small proportion of these SNPs and Indels was mapped to exonic regions of genome: 1.92% and 0.47%, respectively, in the NL group, and 1.66% and 0.48%, respectively, in the WSH group. Gene Ontology (GO) analysis showed that out of 4,890 (NL group) and 1,272 (WSH group) annotated variant genes, 125 and 62 genes were enriched (Q < 0.05), respectively. Additionally, in the Kyoto Encyclopedia of Genes and Genomes (KEGG) database, 104 genes (NL group) and 35 genes (WSH group) were selected (P < 0.05). Finally, 41 genes were filtered and predicted to be associated with tepal shape in lotus.Conclusions: This is the first comprehensive report of genomic variation controlling tepal shape in lotus. Significant genetic variation was detected between the wild-type and mutant lotus genotypes, and varying levels of differentiation between groups NL and WSH. Candidate genes containing epidermal growth factor (EGF) and wall-associated receptor kinase (WAK) domains are considered important targets for further research on tepal development. Overall, the genomic data and candidate genes obtained in this study are essential references for future identification of tepal-shaped control genes in lotus combined with transcriptome analysis and quantitative trait loci (QTL) mapping.