Table_6_Comparative Genomics and Transcriptomics of the Extreme Halophyte Puccinellia tenuiflora Provides Insights Into Salinity Tolerance Differentiation Between Halophytes and Glycophytes.XLSX

Halophytes and glycophytes exhibit clear differences in their tolerance to high levels of salinity. The genetic mechanisms underlying this differentiation, however, remain unclear. To unveil these mechanisms, we surveyed the evolution of salinity-tolerant gene families through comparative genomic analyses between the model halophyte Puccinellia tenuiflora and glycophytic Gramineae plants, and compared their transcriptional and physiological responses to salinity stress. Under salinity stress, the K+ concentration in the root was slightly enhanced in P. tenuiflora, but it was greatly reduced in the glycophytic Gramineae plants, which provided a physiological explanation for differences in salinity tolerance between P. tenuiflora and these glycophytes. Interestingly, several K+ uptake gene families from P. tenuiflora experienced family expansion and positive selection during evolutionary history. This gene family expansion and the elevated expression of K+ uptake genes accelerated K+ accumulation and decreased Na+ toxicity in P. tenuiflora roots under salinity stress. Positively selected P. tenuiflora K+ uptake genes may have evolved new functions that contributed to development of P. tenuiflora salinity tolerance. In addition, the expansion of the gene families involved in pentose phosphate pathway, sucrose biosynthesis, and flavonoid biosynthesis assisted the adaptation of P. tenuiflora to survival under high salinity conditions.

盐生植物（Halophytes）与甜土植物（Glycophytes）对高盐胁迫的耐受性存在显著差异。然而，介导这一分化的遗传机制仍未明确。为揭示该机制，本研究以模式盐生植物星星草（Puccinellia tenuiflora）与甜土型禾本科植物为研究对象，通过比较基因组学分析探究耐盐基因家族的演化历程，并比较二者在盐胁迫下的转录与生理响应。盐胁迫下，星星草根部的钾离子（K+）浓度略有升高，而甜土型禾本科植物根部钾离子浓度则显著下降，这一结果为星星草与这类甜土植物之间的耐盐性差异提供了生理学解释。有趣的是，星星草的多个钾离子吸收基因家族在演化历程中发生了基因家族扩张与正向选择。该基因家族扩张以及钾离子吸收基因的表达上调，加速了盐胁迫下星星草根部的钾离子积累，并降低了钠离子（Na+）毒性。经历正向选择的星星草钾离子吸收基因可能演化出了新功能，这对星星草耐盐性的形成具有重要贡献。此外，参与戊糖磷酸途径、蔗糖生物合成以及黄酮类生物合成的基因家族发生扩张，助力星星草适应高盐胁迫环境并存活。