Generation and characterization of expressed sequence tags in young roots of tea (Camellia assamica)

Abstract

Assam tea (Camellia assamica) is perennial crop susceptible to moisture stress. We used its tender roots to construct a cDNA library for the identification, functional annotation, and analysis of transcripts. A total of 811 full-length expressed sequence tags were generated. After processing and assembly, 207 unigenes comprising 58 contigs and 149 singletons were registered. Finally, 35.75 % of the unigenes could be assigned to functional categories based on the Arabidopsis proteome. There was 43 % of a coding GC content and 1 272 coding DNA sequences found in the unigenes. Codon usage analysis shows leucine as the highest (9.92 %) and tryptophan (2.0 %) as the lowest coded amino acids. Further, a comparative study with drought-induced genes of young roots (reported earlier) reveals that 4.83 % of genes required for normal growth of roots were also induced by a drought stress. Expressions of 10 unigenes under different abiotic stresses, such as drought, cold, and salinity, were further confirmed by RT-qPCR. The sequence tags generated in this study will be valuable resources for functional genomics study of tea and other woody crop plants in future.

Keywords

• cdna library
• contigs
• gene expression
• unigenes