Comparative transcriptome analysis reveals the complex response mechanisms of soybean leaves and roots to salt stress.

backgroundSoil salinization severely affects plant growth and development and has become one of the important abiotic stresses limiting crop growth. To improve soybean yield in saline soils, it is important to understand how soybean responds to salt stress and gain insight into the underlying mechanisms. In this study, we investigated the physiology and molecular expression of soybean (YC03-3) under different salt concentrations by evaluating morphophysiological and transcriptomic approaches.

resultsIn this study, we first analysed the effects of salt stress on soybean leaf and root growth at the physiological level. Salt stress significantly decreased the soluble protein and photosynthetic pigment contents and significantly increased the malondialdehyde (MDA) and reactive oxygen species (ROS) contents of both soybean leaves and roots. Salt stress decreased the nitrogen (N) concentration in leaves but had no effect on the N concentration in roots. Transcriptome sequencing identified 10,508 and 10,827 differentially expressed genes (DEGs) in leaves and roots, respectively. Among these, 2,549 DEGs were co-responsive in both tissues, while 1,601 showed differential responses (e.g., upregulated in one tissue but downregulated in the other).Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses revealed that KEGG pathways for phenylpropanoid biosynthesis were enriched in both soybean roots and leaves under salt stress. In addition, three genes, Glyma.17G230500, Glyma.11G003600, and Glyma.09G192800, were screened by weighted correlation network analysis (WGCNA). These genes may play a key role in breeding salt-tolerant soybeans.

conclusionThe results of this study demonstrate that salt treatment significantly inhibits the growth of soybeans, leading to decreases in the contents of photosynthetic pigments and enhancement of antioxidant enzyme systems in the roots and leaves of soybean plants. As a result, ROS accumulate and MDA levels increase. In addition, the assimilation and transport of ions in soybeans were affected by salt stress. Transcriptome analysis showed that the phenylpropanoid biosynthesis pathway was significantly enriched in soybean roots and leaves under salt stress conditions. In addition, three genes, Glyma.17G230500, Glyma.11G003600 and Glyma.09G192800, were identified by WGCNA screening.