ITRAQ-based Proteomics Analysis Of Lycium Ruthenicum Murr. With Salt (NaCl) Treatment

Salt is one of the main factors limiting the growth and productivity of plants. Study on the way halophytes responding to salt stress would provide valuable information for the salinity-tolerance domestication of crops. This study chooses one of the typical halophytes, Lycium ruthenicum Murr. as the object, adopts the method of physiology combined with proteomics, and applies iTRAQ technologie to analyze the proteome expression of Lycium ruthenicum Murr. under different conditions of salinity, providing the theoretical basis for researches on the salinity-tolerance mechanisms of halophytes and the salinity-tolerance domestication of crops. Major results of this study are as follows:1. The determination of the contents of free proline,p-cumaric acid, and flavonoids in the callus of Lycium ruthenicum Murr. under salt stress shows that through physiological and biochemical regulation of its own adaptability, Lycium ruthenicum Murr. can reduce the damage caused by salt stress. It can be inferred from the callus growth of Lycium ruthenicum Murr. under salt stress and from the change of contents of free proline and malondialdehyde (MDA) that100mM NaCl treatment for7days is the best salt treatment condition for the proteomic analysis of the callus of Lycium mthenicum Murv..2. Using iTRAQ technology,862proteins of Lycium ruthenicum Murr. are identified, in which165show expression differential in mass spectrometry; among the165proteins,72are up-regulated and93are down-regulated.3. The KEGG pathway analysis and GO analysis of the differently expressed proteins of Lycium ruthenicum Murr.show that they are mainly clustered together on the metabolic pathway of energy metabolism and ion transportation term.13of the differently expressed proteins are involved in the energy metabolism,9up-regulated and4down-regulated.4of the differently expressed proteins are involved in ion transportation, all up-regulated. It is thus indicated that the salt stress mainly affects the energy metabolism and ion transportation of Lycium ruthenicum Murr..4.100mM salt treatment promoted the synthesis of flavonoids in Lycium ruthenicum Murr., and the contents of p-coumaric acid show marked increase under such a condition of saliniyt, and pcoumaric acid-3-hydroxylase which is the key enzyme of catalytic p-coumaric acid into lignin pathway decreased. This show that whenLycium ruthenicum Murr. is under salt stress it can promote the accumulation of flavonoids by increasing the amount of p-coumaric acid entering the biosynthetic pathway of flavonoids and consequently it can mitigate salt stress oxidative damage.In summary, this study shows that under salt stress, Lycium ruthenicum Murr. makes osmotic adjustment to free proline and accumulates cumaric acid and flavonoids, this shows it has the ability of salt tolerance. Accumulation of flavonoids may be one of the mechanisms Lycium ruthenicum Murr. adapts to high-salt environment. In this study some valuable proteins are identified, which provides a new basis for further research in the salt-tolerance mechanisms of halophytes.