Susceptibility of Rice Crop to Salt Threat: Proteomic, Metabolomic, and Physiological Inspections

Rice is a staple food crop worldwide;
however, salinity stress
is estimated to reduce its global production by 50%. Knowledge about
initial molecular signaling and proteins associated with sensing salinity
among crop plants is limited. We characterized early salt effects
on the proteome and metabolome of rice tissues. Omics results were
validated by western blotting and multiple reaction monitoring assays
and integrated with physiological changes. We identified 8160 proteins
and 2045 metabolites in rice tissues. Numerous signaling pathways
were induced rapidly or partially by salinity. Combined data showed
the most susceptible proteins or metabolites in each pathway that
likely affected the sensitivity of rice to salinity, such as PLA1,
BON3 (involved in sensing stress), SnRK2, pro-resilin, GDT1, G-proteins,
calmodulin activators (Ca2+ and abscisic acid signaling),
MAPK3/5, MAPKK1/3 (MAPK pathway), SOS1, ABC F/D, PIP2-7, and K+ transporter-23 (transporters), OPR1, JAR1, COL1, ABA2, and
MAPKK3 (phytohormones). Additionally, our results expanded the stress-sensing
function of receptor-like kinases, phosphatidylinositols, and Na+ sensing proteins (IPUT1). Combined analyses revealed the
most sensitive components of signaling pathways causing salt-susceptibility
in rice and suggested potential targets for crop improvement.