Abstract: To study the transcriptomes and genes related to chicle biosynthesis of Manilkara zapota L.，we conducted the RNA sequencing and analysis of M. zapota. The transcriptomes of fruit，bark，and leaf from M. zapota were sequenced on the Illumina platform. The sequencing data were then analyzed by Trinity and other software. qRT-PCR was performed to validate the transcriptome data. The raw data were assembled into 162 455 unigenes，with the total length，mean length，and N50 being 139 792 553 nt，861 nt，and 1 544 nt，respectively. Through mapping all the unigenes to databases，like NR，NT，Swiss-Prot，KEGG，COG，and GO，89 628 unigenes were annotated. In total，57 362 SSR sites were identified taking all the unigenes as references. A total of 99 925，65 989，and 129 109 SNPs were identified in fruit，leaf，and bark expressed genes. In all，105 unigenes were indentified to be chicle-related. The unigenes involved in the MVA pathway were highly expressed in fruit and bark，whereas，the unigenes involved in the MEP pathway were highly expressed in leaf. The gene expression profiles calculated by qRT-PCR were in accordance with those by transcriptome data. The transcriptome was assembled well and the gene expression level calculated by RNA-sequencing was reliable. Plenty of SSRs were indentified，which provides an important basis for the development of molecular markers. According to the expressional profiles of genes involved into chicle biosynthesis，we proposed that the MVA pathway might be the mainly produced initiators for chicle.

Key words: Manilkara zapota, transcriptome, chicle