Plant materials and estimation of genome size
The plants ofO. kokonorica were collected from east side of the Qinghai Lake, Qinghai province, China. Fresh leaves of O. kokonorica were used to extract genomic DNA using a DNA Secure Plant Kit (Tiangen Biotech, Co., Ltd., Beijing, China). Paired-end libraries with insert sizes of 150 bp were constructed and sequenced using the Illumina HiSeq X Ten platform. We used K-mer frequency distribution analysis to estimate genome size (Li et al., 2010). To calculate and plot the K-mer frequency distribution, we used 35.29 Gb of Illumina short reads (Table S1) to determine the total number of K-mers of length 27 using Jellyfish (Marçais & Kingsford, 2011). The selection of 27-mers to plot the frequency distribution was based on genome characteristics and the pattern of the Poisson distribution (Figure S1). We evaluated the ploidy level of this genome using Smudgeplot (Ranallo-Benavidez et al., 2020).