Bhuiyan Mohammad S I, Maynard Greggory, Raman Anantanarayanan, Hodgkins Dennis, Mitchell David, Nicol Helen
Soil Research Group, Charles Sturt University, Leeds Parade, Orange, NSW 2800, Australia.
Charles Sturt University, PO Box 883, Leeds Parade, Orange, NSW 2800, Australia.
Funct Plant Biol. 2016 Mar;43(3):254-265. doi: 10.1071/FP15330.
We measured proline and glycine betaine levels and photosynthetic performance (net-photosynthetic rate (Pn), stomatal conductance (gs), maximum quantum yield of PSII (Fv/Fm) and non-photochemical quenching (NPQ)) in relation to Na+ and Cl- accumulation in Melilotus siculus (Turra) B.D.Jacks. (Fabaceae), Tecticornia pergranulata (J.M.Black) K.A.Sheph. & Paul G.Wilson (Amaranthaceae: Salicornioideae) and Thinopyrum ponticum (Podp.) Z.-W.Liu & R.-C.Wang (Poaceae) grown under saline conditions in the greenhouse. These plants were selected in this study because of their known salt-tolerance capacity and value as forage plants. Moreover, the pasture legume M. siculus is considered to have particular potential for saline land remediation because of its salinity and waterlogging tolerance. Maximum Na+ and Cl- accumulation occurred in Te. pergranulata shoots. Minimum was in Th. ponticum shoots. Maximum Na+ accumulation occurred in the roots of Te. pergranulata, whereas that of Cl- occurred in the roots of Th. ponticum. Accumulation of both Na+ and Cl- was the least in M. siculus roots. Te. pergranulata metabolized high levels of glycine betaine (110µmolg-1 DW). M. siculus metabolized high levels of proline (6µmolg-1 DW). Th. ponticum accumulated intermediate levels of these organic osmolytes. No significant change occurred in Fv/Fm values. Pn value increased and NPQ value decreased in Te. pergranulata with increasing salinity and the reverse occurred in both M. siculus and Th. ponticum. A negative significant correlation occurred between Pn and glycine betaine in M. siculus and Th. ponticum. A positive significant correlation occurred between NPQ and glycine betaine in M. siculus. No correlation occurred between proline and Pn, proline and NPQ in the tested three plants. Te. pergranulata could maintain cell-osmotic balance by synthesising high levels of organic osmolytes especially glycine betaine and concurrently showing the most efficient photosynthetic performance. Compared with the levels of osmolytes in Te. pergranulata, the levels of osmolytes that occur in M. siculus and Th. ponticum were insufficient to maintain cell-osmotic balance and also that M. siculus and Th. ponticum showed a lower level of photosynthetic performance. We conclude that glycine betaine is potentially the vital organic osmolyte for Te. pergranulata and Th. ponticum enabling salinity stress tolerance. However, in M. siculus, proline appears to be the potential organic osmolyte in salinity stress tolerance. In terms of the potential of these species for stabilising saline soils in central-western New South Wales, Te. pergranulata would be the candidate of choice; however, for greater pasture value Th. ponticum would be the next.
我们测定了在温室盐胁迫条件下生长的西西里草木犀（豆科）、颗粒盐角草（苋科：盐角草亚科）和蓬蒂三角草（禾本科）中脯氨酸和甘氨酸甜菜碱的含量以及光合性能（净光合速率（Pn）、气孔导度（gs）、PSII最大量子产量（Fv/Fm）和非光化学猝灭（NPQ）），这些指标与Na⁺和Cl⁻积累的关系。本研究选择这些植物是因为它们已知的耐盐能力和作为饲料植物的价值。此外，豆科牧草西西里草木犀因其耐盐和耐涝能力，被认为在盐碱地修复方面具有特殊潜力。颗粒盐角草地上部分的Na⁺和Cl⁻积累量最大，蓬蒂三角草地上部分的积累量最小。颗粒盐角草根中Na⁺积累量最大，而蓬蒂三角草根中Cl⁻积累量最大。西西里草木犀根中Na⁺和Cl⁻的积累量最少。颗粒盐角草代谢高水平的甘氨酸甜菜碱（110μmol g⁻¹干重），西西里草木犀代谢高水平的脯氨酸（6μmol g⁻¹干重），蓬蒂三角草积累这些有机渗透剂的水平居中。Fv/Fm值没有显著变化。随着盐度增加，颗粒盐角草的Pn值升高，NPQ值降低，而西西里草木犀和蓬蒂三角草则相反。西西里草木犀和蓬蒂三角草的Pn与甘氨酸甜菜碱之间存在显著负相关。西西里草木犀的NPQ与甘氨酸甜菜碱之间存在显著正相关。在所测试的三种植物中，脯氨酸与Pn、脯氨酸与NPQ之间均无相关性。颗粒盐角草可以通过合成高水平的有机渗透剂尤其是甘氨酸甜菜碱来维持细胞渗透平衡，同时表现出最有效的光合性能。与颗粒盐角草的渗透剂水平相比，西西里草木犀和蓬蒂三角草中的渗透剂水平不足以维持细胞渗透平衡，并且西西里草木犀和蓬蒂三角草的光合性能水平较低。我们得出结论，甘氨酸甜菜碱可能是颗粒盐角草和蓬蒂三角草耐盐胁迫的重要有机渗透剂。然而，在西西里草木犀中，脯氨酸似乎是耐盐胁迫的潜在有机渗透剂。就这些物种在新南威尔士中西部稳定盐碱土壤的潜力而言，颗粒盐角草将是首选；然而，就更高的牧草价值而言，蓬蒂三角草将是次选。
