Transcriptomic and Physiological Analyses Reveal the Dynamic Response to Salinity Stress of the Garden Asparagus (Asparagus officinalis L.)

Soil salinity is a major abiotic stress that affects crop productivity. Garden asparagus (Asparagus officinalis L.) is a perennial plant with some salt tolerance. However, little is known about its response mechanism to salinity stress. In this study, we conducted transcriptome analysis in the leaves of A. officinalis seedlings treated with NaCl solution for 0 h, 1 h, 24 h, and 72 h using the Illumina HiSeq (TM) 2500 sequencing platform. Compared with the control (0 h), 1027, 3387, and 3358 differentially expressed genes (DEGs) were identified at 1 h, 24 h, and 72 h, respectively. The Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses revealed that these DEGs were highly enriched in carbon metabolism, ion transport, and reactive oxygen species (ROS) metabolism functional categories, suggesting their key positions in salinity stress responses. Moreover, k-means clustering categorized these DEGs into five kinds of expression patterns at four time points. Of these, DEGs involved in carbon metabolism, ion transport, and ROS metabolism and the groups which they belonged to were identified, which demonstrated their time-dependent response mechanisms. Overall, the transcriptome analysis shed light on the salinity stress response mechanisms in A. officinalis and provided a basis for future studies on salt-tolerance molecular improvement.