Key Laboratory of State Forestry and Grassland Administration on Grass Germplasm Resources Innovation and Utilization in the Middle and Lower Reaches of the Yangtze River, College of Grassland Science, Nanjing Agricultural University, Nanjing, 210095, China.
Plant J. 2024 Sep;119(6):2782-2796. doi: 10.1111/tpj.16949. Epub 2024 Jul 26.
SODIUM SYMPORTER FAMILY PROTEIN 2 (BASS2) is localized within chloroplast membranes, facilitating the translocation of pyruvate and Na from the cytosol to the plastid, where pyruvate supports isopentenyl diphosphate (IPP) synthesis via the methylerythritol phosphate pathway in C3 plants. Nevertheless, the biological function of BASS2 in C4 plants has not been well defined. This study unveils a previously unidentified role of PvBASS2 in Na and pyruvate transport in seashore paspalum (Paspalum vaginatum), a halophytic C4 grass, indicating a specific cellular function within this plant species. Data showed that overexpression of PvBASS2 in seashore paspalum attenuated salt tolerance, whereas its RNAi lines exhibited enhanced salt resistance compared to wild-type plants, suggesting a negative regulatory role of PvBASS2 in seashore paspalum salt tolerance. The constitutive overexpression of PvBASS2 was also found to reduce salt tolerance in Arabidopsis. Further study revealed that PvBASS2 negatively regulates seashore paspalum salt tolerance, possibly due to elevated Na/K ratio, disrupted chloroplast structure, and reduced photosynthetic efficiency following exposure to salinity. Importantly, our subsequent investigations revealed that modulation of PvBASS2 expression in seashore paspalum influenced carbon dioxide assimilation, intermediary metabolites of the tricarboxylic acid cycle, and enzymatic activities under salinity treatment, which in turn led to alterations in free amino acid concentrations. Thus, this study reveals a role for BASS2 in the C4 plant seashore paspalum and enhances our comprehension of salt stress responses in C4 plants.
SODIUM SYMPORTER FAMILY PROTEIN 2 (BASS2) 定位于叶绿体膜内，促进细胞质中的丙酮酸和 Na 向质体的转运，在 C3 植物中，丙酮酸通过甲基赤藓醇磷酸途径支持异戊烯二磷酸（IPP）的合成。然而，BASS2 在 C4 植物中的生物学功能尚未得到很好的定义。本研究揭示了 PvBASS2 在滨海雀稗（Paspalum vaginatum）中作为一种盐生 C4 草，在 Na 和丙酮酸转运中的一个以前未被识别的作用，表明了其在该植物物种中具有特定的细胞功能。研究数据表明，滨海雀稗中 PvBASS2 的过表达削弱了其耐盐性，而其 RNAi 系相对于野生型植物表现出增强的耐盐性，表明 PvBASS2 在滨海雀稗耐盐性中具有负调节作用。PvBASS2 的组成型过表达也被发现降低了拟南芥的耐盐性。进一步的研究表明，PvBASS2 负调节滨海雀稗的耐盐性，可能是由于盐胁迫下 Na/K 比值升高、叶绿体结构破坏和光合作用效率降低。重要的是，我们随后的研究表明，滨海雀稗中 PvBASS2 表达的调节影响了二氧化碳同化、三羧酸循环中间代谢物以及盐处理下的酶活性，进而导致游离氨基酸浓度的变化。因此，本研究揭示了 BASS2 在 C4 植物滨海雀稗中的作用，并增强了我们对 C4 植物盐胁迫响应的理解。
