青藏高原4种葱属叶绿体基因组比较及系统发育分析OA

To investigate the chloroplast genome characteristics and phylogenetic relationships of four Allium species from the Qinghai-Tibet Plateau,high-throughput Illumina NovaSeq 6000 reads were sequenced for A.carolinianum,A.tenuissimum,A.tanguticum,and A.polyrhizum.Comprehensive bioinformatic analyses were subsequently conducted to explore sequence features,codon usage bias,and phylogenetic relationships.The chloroplast genomes of the four Alliumspecies ranged from 152 916 to 153 766 bp,each encoding 132 genes with a GC content of 36.71%-36.85%.Thirty high-frequency codons were identified in A.carolinianum,A.tenuissimum,and A.polyrhizum,while A.tanguticum exhibited 32.All four species displayed a pronounced A/U bias at the third codon posi-tion.A total of 83-97 SSR loci were detected,with mononucleotide motifs predominant.Both A.car-olinianum and A.tanguticum harbored a single hexanucleotide SSR locus.Comparative analyses re-vealed elevated divergence within the LSC and SSC regions,yielding nine hypervariable loci,among which rpl32-trnL(pi=0.061)exhibited the highest variability and was proposed as a candidate DNA barcode.Phylogenetic analysis indicated that A.tenuissimum,A.polyrhizum,and A.senescens formed a small clade,while A.tanguticum,A.carolinianum,A.xichuanense,A.chrysanthum,A.chrysocephalum,A.cepa and A.altaicum constituted a separate,closely related lineage.