Serratia liquefaciens KM4 Improves Salt Stress Tolerance in Maize by Regulating Redox Potential, Ion Homeostasis, Leaf Gas Exchange and Stress-Related Gene Expression. . doi: 10.3390/ijms19113310
, El-Esawi Mohamed A., Ibrahim A. Alaraidh, Abdulaziz A. Alsahli, Saud M. Alzahrani, Hayssam M. Ali, Aisha A. Alayafi and Margaret Ahmad . 2018
High salinity mitigates crop productivity and quality. Plant growth-promoting soil
rhizobacteria (PGPR) improve plant growth and abiotic stress tolerance via mediating various
physiological and molecular mechanisms. This study investigated the effects of the PGPR strain
Serratia liquefaciens KM4 on the growth and physiological and molecular responsiveness of maize
(Zea mays L.) plants under salinity stress (0, 80, and 160mMNaCl). High salinity significantly reduced
plant growth and biomass production, nutrient uptake, leaf relative water content, pigment content,
leaf gas exchange attributes, and total flavonoid and phenolic contents in maize. However, osmolyte
content (e.g., soluble proteins, proline, and free amino acids), oxidative stress markers, and enzymatic
and non-enzymatic antioxidants levels were increased in maize under high salinity. On the other hand,
Serratia liquefaciens KM4 inoculation significantly reduced oxidative stress markers, but increased
the maize growth and biomass production along with better leaf gas exchange, osmoregulation,
antioxidant defense systems, and nutrient uptake under salt stress. Moreover, it was found that all
these improvements were accompanied with the upregulation of stress-related genes (APX, CAT,
SOD, RBCS, RBCL, H+-PPase, HKT1, and NHX1), and downregulation of the key gene in ABA
biosynthesis (NCED). Taken together, the results demonstrate the beneficial role of Serratia liquefaciens
KM4 in improving plant growth and salt stress tolerance in maize by regulating ion homeostasis,
redox potential, leaf gas exchange, and stress-related genes expression.
