Paraburkholderia sp. GD17 improves rice seedling tolerance to salinity

Ruanming Zhu,Guangzhe Li,Lianju Ma,Yuting Cao,Lin Hao,Ning Bu,Ying Guo

doi:10.1007/s11104-021-05108-3

Abstract

The plant growth promoting rhizobacteria have been extensively implicated in plant responses to changing environments. However, the action mechanisms still need to be elucidated. This study addressed the effect of Paraburkholderia sp. GD17 on rice seedlings in responses to salt stress. The experiment consisted of GD17-inoculated and non-inoculated plants, with or without NaCl treatment. Physiological and biochemical parameters, and gene expression were analyzed. GD17 efficiently colonized inside roots, and provided a protection against salt stress. Following exposure to 68 mM of NaCl for 48 h, although the accumulation of Na+ was not affected in GD17-inoculated (+ GD17) roots relative to non-inoculated ones, its concentration was substantially reduced in + GD17 shoots. The contents of K and other mineral elements were higher in + GD17 plants. The expression of Na+ and K+ transporter-encoding genes generally presented a higher level in + GD17 plants. The antioxidative defense especially related to the removal of H2O2 was more strongly activated in + GD17 plants. Correspondingly, salt-induced oxidative damage was significantly ameliorated. A substantial increase in proline content and gene expression was observed in + GD17 plants. Additionally, the cell wall invertase-encoding gene displayed a dramatically higher expression level in + GD17 plants. GD17 efficiently improved rice seedling tolerance to salt stress. The possible mechanisms might be associated with the absorption and redistribution of mineral elements, the vacuolar sequestration of Na+ as well as exclusion of Na+, antioxidative defense, the production of proline, and the sucrose catabolism in apoplast.

Highlights

Salinity is one of the major abiotic factors limiting plant growth, development, and productivity in agriculture (Pitman and Läuchli 2002)
The present study explored the effect of GD17 symbiosis with rice roots on seedling growth and responses to
The result showed that no GD17 strain was found in root interior before the inoculation, while substantial numbers of GD17 were detected after 2 h of inoculation, and it dramatically increased with the extension of inoculation duration as indicated by colony-forming units (CFU) (Fig. 1), and by the estimate of 16S rRNA accumulation (Fig. S2)

Summary

Introduction

Salinity is one of the major abiotic factors limiting plant growth, development, and productivity in agriculture (Pitman and Läuchli 2002). 6% of the world’s total land area) is affected by excess salt concentrations (Munns and Tester 2008), and this problem continues to worsen. Excess salts in the soil induce plant osmotic stress by reducing the water potential limiting water uptake (Hasegawa et al 2000), while the excessive uptake of Na+ and Cl- leads to ionic stress by affecting the absorption and distribution of essential elements, interfering with various metabolic processes (Lazof and Bernstein 1999). Either the osmotic or the ionic stress can cause plant secondary stress, typically by producing and accumulating reactive oxygen species (ROS), such as superoxide anion (O2 ̇ˉ), hydrogen peroxide (H2O2) and hydroxyl radical ( ̇OH).

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Conclusion