Role of glycine in improving the ionic and ROS homeostasis

Nine-day-old wheat seedlings were treated with

NaCl at 75, 150, and 225 mM for 15 days in the absence or

presence of 5 mM glycine. NaCl particularly at 150 and

225 mMled to significant reductions in fresh and dry weights,

chlorophylls, carotenoids, Ca2+, K+, and K+/Na+ ratio. Contrarily,

there were significant accumulations in Na+,

malondialdehyde (MDA), H2O2, soluble sugars, and proline

concomitant with inhibitions in enzymatic and non-enzymatic

antioxidants and in Rubisco. In the meantime, the transcript

level of alternative oxidase (AOX) was highly upregulated by

NaCl; the upregulation was greatest with the lowest concentration.

However, the transcript level of H+/Na+ antiporter

exchanger (NHX1) was decreased by 75 and 150 mM NaCl

but increased by 225 mM. Similarly, the transcript level of salt

overly sensitive 1 (SOS1) was upregulated by only 225 mM.

Nonetheless, the application of glycine mostly overcame the

varied impacts of NaCl on growth, MDA, H2O2, pigments,

metabolites, and elements. Moreover, glycine elevated enzymatic

and non-enzymatic antioxidants to reach most likely the

levels of the respective control. On the contrary, much induction

was detected in Rubisco. The transcript levels of AOX,

NHX1, and SOS1 were further upregulated; the upregulation

of AOX was most pronounced with the highest NaCl concentration

in the presence of glycine and only with 75 and

150 mM NaCl for NHX1 and SOS1. The increase in antioxidants

concomitant with the decrease in MDA and H2O2

reveals that ROS scavenging system became more efficient

in NaCl-treated wheat following glycine application, concluding

that glycine could ameliorate wheat tolerance to salinity