Abstract
BackgroundThe interaction between arbuscular mycorrhizal fungi (AMF) and AMF spore associated bacteria (SAB) were previously found to improve mycorrhizal symbiotic efficiency under saline stress, however, the information about the molecular basis of this interaction remain unknown. Therefore, the present study aimed to investigate the response of maize plants to co-inoculation of AMF and SAB under salinity stress.ResultsThe co-inoculation of AMF and SAB significantly improved plant dry weight, nutrient content of shoot and root tissues under 25 or 50 mM NaCl. Importantly, co-inoculation significantly reduced the accumulation of proline in shoots and Na+ in roots. Co-inoculated maize plants also exhibited high K+/Na+ ratios in roots at 25 mM NaCl concentration. Mycorrhizal colonization significantly positively altered the expression of ZmAKT2, ZmSOS1, and ZmSKOR genes, to maintain K+ and Na+ ion homeostasis. Confocal laser scanning microscope (CLSM) view showed that SAB were able to move and localize into inter- and intracellular spaces of maize roots and were closely associated with the spore outer hyaline layer.ConclusionThese new findings indicate that co-inoculation of AMF and SAB effectively alleviates the detrimental effects of salinity through regulation of SOS pathway gene expression and K+/Na+ homeostasis to improve maize plant growth.
Highlights
The interaction between arbuscular mycorrhizal fungi (AMF) and AMF spore associated bacteria (SAB) were previously found to improve mycorrhizal symbiotic efficiency under saline stress, the information about the molecular basis of this interaction remain unknown
A significantly negative effect of salinity on growth of the plant was observed in all the treatments and a more prominent effect was evident at the highest salt concentration of 50 mM NaCl
In conclusion, our study indicates that co-inoculation of AMF and SAB improved the growth and salt tolerance of maize
Summary
The interaction between arbuscular mycorrhizal fungi (AMF) and AMF spore associated bacteria (SAB) were previously found to improve mycorrhizal symbiotic efficiency under saline stress, the information about the molecular basis of this interaction remain unknown. The present study aimed to investigate the response of maize plants to co-inoculation of AMF and SAB under salinity stress. The salinity of soil is one of the most important concerns, which are increasing progressively worldwide. More than 800 million hectares (over 6%) of the world’s total land area are affected by soil salinity (FAO 2005). Increasing salinization of arable lands adversely affects crop establishment, growth, and development contributing to huge losses in productivity [1, 2]. The high concentration of salt present in the soil causes both hyper-ionic and hyper-osmotic stress and leads to plant death [3]. Na+ is a major ion and under salt stress, it causes ion toxicity in plants [10]
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