De Novo Assembly of Transcriptome Sequencing and EST-SSR development in Aesculus chinensis Bunge

Aesculus chinensis Bunge ( A. chinensis Bunge), a deciduous tree in the genus Aesculus of the family Hippocastanaceae. and has ornamental, economic and medicinal values. Lack of comprehensive genetic information hinders the development and further utilization of this species and EST-SSR markers of A. chinensis Bunge have not been previously reported. For this reason we obtained A. chinensis Bunge transcriptomes using Illumina HiSeq TM2000 and de novo assembly, developed the EST-SSR markers. In this study, 74,805,734 clean reads were generated using Illumina HiSeq TM2000 and obtained 33,365 unigenes with a mean length of 1348bp after assembly. A total of 25450 (76.27%) unigenes showed similarities in at least one database including Nr (71.39%), Swiss Prot (57.03%), GO (53.31%), KO (27.13%) and KOG (19.27%). Based on the transcriptome data collected for A. chinensis Bunge, 16,103 SSR loci were detected with the distribution density of one SSR per 2.79 kb. The most dinucleotide and trinucleotide repeats were AG/CT and AAG/CTT. Then 58 primer pairs were randomly selected for polymorphism validation and 31 primer pairs were polymorphic among eight Aesculus species. A total of 167 alleles were identified, varying from 2 to 9 with a mean of 5.387 alleles per locus.