De novo transcriptome analysis of pneumatophores (modified roots) in the true mangrove species Avicennia marina and identification of the genes related to root gas exchange

Abstract

Mangroves plants which grow in estuaries naturally tolerate extreme conditions of high salinity (90 ppt) and high light intensity. Avicennia marina is a true mangrove tree species with physiological adaptations like modified root system (pneumatophores) and salt excretion glands in leaves as its one of the unique features to consider. The pneumatophores are a special type of roots with negative geotropism that project above the water surface or the level of flooded soils [1]. In contact with air these roots develop lenticels, which improve gas exchange between roots and environment [2]. In swamps and wetlands the presence of pneumatophores facilitates oxygen diffusion through the tissues, maintaining levels adequate for cellular respiration [3]. Objective of this study was to perform the whole transcriptome analysis of pneumatophore tissue of A. marina by Illumina sequencing and to identify putative genes involved in process of root gas exchange. We generated 19.73 million of paired-end reads and assembled into 86,856 unigenes with an average length of 772 bp. Further, annotation, tissue specific gene expression and genes related to root gas exchange will be presented.