De novo Transcriptome Analysis of Cold Tolerant Mangrove Kandelia obovata

Kandelia obovata, a species of Rhizophoraceae, is one of the most cold-tolerant mangroves. Living in the intertidal environment, it forms a series of adaptive traits including viviparity. In this work, transcriptomes from eight tissues of K. obovata were sequenced by Illumina platform. After de novo assembly, we obtained a total of 115,771 unigenes. Gene Ontology analysis revealed that most of the unigenes were assigned to cell and cell part in cellular component category, assigned to protein binding in molecular function category. In biological process category, cellular process, biological process and response to stress were the most enriched. Further detailed classification of response to stress showed that a large number of unigenes were annotated to response to salt stress, cold, water deprivation and bacterial defense. KEGG pathway analysis shown that most of unigenes participate in ribosome, biosynthesis of amino acids, carbon metabolism and RNA transports, pathways that are also highly associated with plant response to adverse conditions. Furthermore, we identified 54 transcription factor families in K. obovata, among which bHLH, NAC, MYB families occupy a large proportion. These results indicated that the most enriched functions, pathways and highly representative transcription factors may be essential for K. obovata growth and response to intertidal environment, thus it shed light on molecular ecological understanding of this special group of coastally adapted habitats. In addition, the results of differential gene expression patterns and their relationship to cold tolerance and potentially vivipary will be presented.