Abstract
Background Kiwifruit [Actinidia deliciosa (A Chev) Liang et Ferguson] is a sub-tropical vine from the Actinidiaceae family native from China. This specie has an allohexaploid genome (from a diploid and autotetraploid parents) contained in 174 chromosomes producing a climacteric and fleshy fruit called kiwifruit. Currently there's no too much genomic and transcriptomic information about this species. In this low molecular knowledge context, the main goal of this work is to construct a tissue-specific de novo transcriptome assembly generating a differential expression analysis among these specific tissues to obtain new useful database for a better knowledge of vegetative, floral and fruit growth in different phenological states of Actinidia deliciosa cv. ‘Hayward’. Results In the present study we have analyzed different whole transcriptomes from shoot, leaf, flower bud, flower and fruit at 4 development stages (7,50,120 and 160 days after flowering; DAF) in kiwifruit by using RNA-seq. We sequenced twenty-four libraries, obtaining 604,735,364 reads which were assembled using Trinity software. The first version of Actinidia deliciosa de novo transcriptome contained 142,025 contigs (x̅=1,044bp, N50=1,133bp). CEGMA and BUSCO were used for assembly quality assessment, obtaining close to 90.0% (35.1% partial) and over 85.0% (18.3% partial) of the ultra-conserved genes for eukaryote and plants, respectively. Annotation was performed with BLASTx against TAIR10 protein database and we found an annotation proportion of 35.6% (50,508), leaving 64.4% (91,517) of the contigs assembly without annotation. Conclusions These results represent a reference transcriptome for allohexaploid kiwifruit generating a database of Actinidia deliciosa genes related to leaf, flower and fruit development. Thus, the present study provides a high valuable information, identifying over 20,000 exclusive genes including all tissue comparisons, which are associated with the proteins involved in different biological processes and molecular functions. Transcriptome assembly and refining as well as the assembly metric assessment, has implied an enough quality to be a putative database of this specie and high number of ultra-conserved proteins were found. With respect to transcriptome close to 65% of contigs did not match with any protein. Therefore, future functional annotation will be required in order to obtain a better knowledge of the tissue-specific development.
Tissue-specific de novo transcriptome analysis in kiwifruit [Actinidia deliciosa (A Chev) Liang et Ferguson]
