Transcriptome Analysis Of The Primary Roots Of Alhagi Sparsifolia In Response To Water Stress

Alhagi sparsifolia is a typical desert phreatophyte,which can withstand the harsh ecological environment especially the extreme drought and is mainly distributed in the desert and Gobi area of Xinjiang, P. R. China as well as Central Asia.While A. sparsifolia represents an ideal model to study the molecular mechanism of plant adaption to abiotic stress, no research has been done in this aspect to date. It is momentous for culturing drought resistant crops and promoting water-saving agriculture to study the drought mechanism of A. sparsifolia in the molecular level because of less than less water in the world. Here we took advantage of Illumina platform to survey transcriptome in primary roots of A. sparsifolia under water stress conditions in aim to facilitate the exploration of its genetic basis for drought tolerance.We sequenced four primary roots samples individually collected at 0, 6, 24 and 30 h from the A. sparsifolia seedlings upon 24 h of water stress following 6h of rehydration. The resulting 38,763,230, 67,511,150, 49,259,804 and 54,744,906 clean reads were pooled and assembled into 33,255 unigenes with an average length of 1,057 bp. All-unigenes were subjected to functional annotation by searching against the public databases. Based on the established transcriptome database, we further evaluated the gene expression profiles in the four different primary roots samples, and identified numbers of differently expressed genes(DEGs) reflecting the early response to water stress(6h), the late response to water stress(24h) and the response to post stress rehydration(30h). Moreover, the DEGs specifically regulated at 6, 24 and 30 h were captured in order to depict the dynamic changes of gene expression during water stress and subsequent rehydration. Functional categorization of the DEGs indicated the activation of oxidoreductase system, and particularly emphasized the significance of the ‘Glutathione metabolism pathway’ in response to water stress.To sum up, we analysed the A. sparsifolia transcriptome which responses to water stress by RNA-seq, and studied the mechanism of drought tolerance in the molecular level. This is the first description of the genetic makeup of A. sparsifolia, thus providing a substantial contribution to the sequence resources for this species. The identified DEGs offer a deep insight into the molecular mechanism of A. sparsifolia in response to water stress, and merit further investigation.