Department of Plant Biology, University of Georgia, Athens, Georgia 30602.
Department of Plant Biology, University of Georgia, Athens, Georgia 30602
Plant Physiol. 2020 Dec;184(4):2107-2119. doi: 10.1104/pp.20.00796. Epub 2020 Oct 20.
Salinity is a growing issue worldwide, with nearly 30% of arable land predicted to be lost due to soil salinity in the next 30 years. Many grass crops that are vital to sustain the world's caloric intake are salt sensitive. Studying mechanisms of salt tolerance in halophytic grasses, plants that thrive in salt conditions, may be an effective approach to ultimately improve salt-sensitive grass crops. Seashore paspalum () is a halophytic Panicoid grass able to grow in salt concentrations near that of seawater. Despite its widespread cultivation as a sustainable turfgrass, the mechanism underlying its ability to retain high Na concentrations in photosynthetic tissue while maintaining growth remains unknown. We examined the leaf structure and ion content in 'HI10', which shows increased growth under saline conditions, and 'Spence', which shows reduced growth under salt, to better understand the superior salt tolerance of cv HI10. A striking difference between cv HI10 and cv Spence was the high steady-state level of K in cv HI10. Imaging further showed that the adaxial surface of both cv HI10 and cv Spence contained dense costal ridges of papillae. However, these unicellular extensions of the epidermis were significantly larger in cv HI10 than in cv Spence. The cv HI10 papillae were shown to act as Na sinks when plants were grown under saline conditions. We provide evidence that leaf papillae function as specialized structures for Na sequestration in , illustrating a possible path for biotechnological improvement of salt-sensitive Panicoid crops with analogous leaf structures.
盐度是全球日益严重的问题，预计在未来 30 年内，近 30%的可耕地将因土壤盐度而丧失。许多对维持世界热量摄入至关重要的草本作物对盐敏感。研究盐生植物（在盐条件下茁壮成长的植物）的耐盐机制可能是最终提高盐敏感草本作物的有效方法。海滨雀稗（）是一种盐生 Panicoid 草，能够在接近海水盐度的盐浓度下生长。尽管它被广泛种植为可持续草坪草，但它在光合组织中保留高 Na 浓度同时保持生长的能力的机制仍然未知。我们检查了在盐条件下生长增加的 'HI10' 和在盐条件下生长减少的 'Spence' 的叶片结构和离子含量，以更好地了解 cv HI10 的卓越耐盐性。cv HI10 和 cv Spence 之间的一个显著区别是 cv HI10 中的 K 稳态水平高。成像进一步显示，cv HI10 和 cv Spence 的近轴表面都含有密集的肋状乳突。然而，这些表皮的单细胞延伸在 cv HI10 中比在 cv Spence 中大得多。当植物在盐条件下生长时，cv HI10 的乳突被证明是 Na 的汇。我们提供的证据表明，叶片乳突在海滨雀稗中作为 Na 螯合的特化结构发挥作用，为具有类似叶片结构的盐敏感 Panicoid 作物的生物技术改良提供了一种可能的途径。
