Soil salinity of fields is often non-uniform. To obtain a better understanding of molecular response to non-uniform salt stress, we conducted transcriptomic analysis on the leaves and roots of alfalfa grown under 0/0, 200/200, and 0/200 mM NaCl treatments. A total of 233,742 unigenes were obtained from the assembled cDNA libraries. There were 98 and 710 unigenes identified as significantly differentially expressed genes (DEGs) in the leaves of non-uniform and uniform salt treatment, respectively. Furthermore, there were 5178 DEGs in the roots under uniform salt stress, 273 DEGs in the non-saline side and 4616 in the high-saline side roots under non-uniform salt stress. Alfalfa treated with non-uniform salinity had greater dry weight and less salt damage compared to treatment with uniform salinity. The Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis of the DEGs in roots revealed that both sides of the non-uniform salinity were enriched in pathways related to "phenylpropanoid biosynthesis" and "linoleic acid metabolism"; and "MAPK signaling pathway-plant" was also indicated as a key pathway in the high-saline roots. We also combined a set of important salt-response genes and found that roots from the non-saline side developed more roots with increased water uptake by altering the expression of aquaporins and genes related to growth regulation. Moreover, the hormone signal transduction and the antioxidant pathway probably play important roles in inducing more salt-related genes and increasing resistance to non-uniform salt stress on both sides of the roots.

中文翻译：

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非均匀盐胁迫下苜蓿耐盐性相关基因和途径的转录组分析。

田地的土壤盐分常常不均匀。为了更好地理解分子对盐胁迫的响应，我们对在0 / 0、200 / 200和0/200 mM NaCl处理下生长的苜蓿的叶和根进行了转录组学分析。从组装的cDNA文库中总共获得233,742个单基因。在不均匀和均匀盐处理的叶片中，分别有98和710个单基因被鉴定为显着差异表达的基因（DEG）。此外，在均匀盐胁迫下，根系中有5178个DEG，在非盐胁迫侧中有273个DEG，在不均匀盐胁迫下高盐侧中的4616个。与盐度均匀的处理相比，盐度不均匀的紫花苜蓿干重更大，盐害更少。对根中DEGs进行的京都基因与基因组百科全书（KEGG）途径富集分析表明，盐度不均匀的两侧都富集与“苯丙烷生物合成”和“亚油酸代谢”有关的途径；“ MAPK信号传导途径-植物”也被认为是高盐根中的关键途径。我们还结合了一组重要的盐响应基因，发现通过改变水通道蛋白的表达和与生长调节相关的基因，来自非盐侧的根发育出更多的根，并增加了水分吸收。此外，激素信号转导和抗氧化剂途径可能在诱导更多与盐有关的基因以及增加对根部两侧不均匀盐胁迫的抗性中起重要作用。